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Howto Pass SSH traffic through a Secured Corporate Proxy server with corkscrew, using sshd as a standalone proxy service with no proxy installed on remote Linux server or VPS

Tuesday, November 19th, 2019

howto pass ssh traffic through proxy to remote server use remote machine as a proxy for connecting to the Internet

Working in the big bad corporate world (being employed in  any of the Fortune 500) companies, especially in an IT delivery company is a nasty thing in terms of User Personal Data Privacy because usually when employeed in any of a corporation, the company ships you with a personal Computer with some kind of pre-installed OS (most often this is Windows) and the computer is not a standalone one but joined in Active Directory (AD) belonging to Windows Domain and centrally administered by whoever.

As part of the default deplyed configuration in this pre-installed OS and software is that part or all your network traffic and files is being monitored in some kind of manner as your pre-installed Windows or Linux notebook given by the Corporation is having a set of standard software running in the background, and even though you have Windows Administrator there are many things you have zero control or even if you have changed it once the Domain Policy is triggered your custom made changes / Installed Programs that happen to be against the company policy are being automatically deleted, any registry changes made are being rewinded etc. Sometimes even by trying to manually clean up your PC from the corporate crapware,  you might breaks access to the corporate DMZ firewalled network. A common way to secure their employee PC data large companies have a Network seperation, your PC when not connected to the Corporate VPN is having a certain IP configuration and once connected to the Demilitarized Zone VPN those configuration changes and the PC have access to internal company infrastructure servers / router / switches / firewalls / SANs etc. Access to corporate Infrastructure is handled via crypted VPN clinet such as Cisco AnyConnect Secure Mobility Client which is perhaps one of the most used ones out there.

Part of the common software installed to Monitor your PC for threats / viruses / trojans among which is MCafee / EMET (Enhandced Mitigation Experience Toolkit) the PC is often prebundled with some kind of anti-malware (crapware) :). But the tip of the iceberg on user surveillance where most of surveillance happens is the default installed proxy on the PC which usually does keep track of all your remote accessed HTTP Website URLs accessed in plain text – traffic flowing on Port 80 and crypted one on standard (SSL) Port 443. This Web Traffic is handled by the Central Corporate proxy that is being deployed via some kind of Domain policy, every time the Computer joins the Windows domain. 

This of course is a terrible thing for your Browsing security and together with the good security practice to run your browser in Incognito mode, which makes all your browsing activity such as access URLs History or Saved Cookies data to be cleared up on a Browser close it is important to make sure you run your own personal traffic via a separate browser which you will use only for your own concern browsing such as Accessing your Bank Money Accounts to check your Monthly Sallary / Purchase things online via Amazon.com / Ebay.com, whether all of the rest traffic company related is trafficed via the default set corporate central proxy.
This is relatively easy sometimes in companies, where security is not of a top concern but in corporations with tightened security accessing remote proxy, or accessing even common daily news and Public Email websites or social media sites  Gmail.com / Twitter / Youtube will be filtered so the only way to reach them will be via some kind of Proxy and often this proxy is the only way out to the Free world from the corporate jail.

Here is where the good old SSH comes as a saving grace as it turns out SSH traffic could be trafficed over a proxy. In below article I will give you a short insight on how Proxy through SSH could be achieved to Secure your dailty web traffic and use SSH to reach your own server on the Internet as well as how you can copy securely data via SSH through corporate Proxy. 
 

1. How to view your corporate used (default) proxy / Check Proxy.pac file definitions

 

To get an idea what is the used proxy on your Corporate PC (as most corporate employee given notebooks are running some kind of M$ Windows)  you can go to:

Windows Control Panel -> Internet Options -> Connections -> Lan Settings


internet-properties-microsoft-windows-screenshot

Under the field Proxy server (check out the Proxy configured Address and Port number )

local-area-network-lan-settings-screenshot-windows-1
 

Having that as browsers venerate the so-called Proxy.pac file, to be rawly aware on some general Company Proxy configured definitions you can access in a browser the proxy itself fething the proxy.pac file for example.

 

http://your-corporate-firewall-rpoxy-url:8080/proxy.pac

 

This is helpful as some companies Proxies have some proxy rules that reveal some things about its Internet architecture and even some have some badly configured proxy.pac files which could be used to fool the proxy under some circumstances 🙂
 

2. Few of the reasons corporations proxy all their employee's work PC web traffic

 

The corporate proxying of traffic has a number of goals, some of which are good hearted and others are for mostly spying on the users.

 

1. Protect Corporate Employees from malicious Viruses / Trojans Horses / Malware / Badware / Whatever ware – EXCELLENT
2. Prevent users from acessing a set of sources that due to the corporate policy are considered harmful (e.g. certain addresses 
of information or disinformation of competitors, any Internet source that might preach against the corporation, hacking ralated websites etc.) – NOT GOOD (for the employee / user) and GOOD for the company
3.Spy on the users activity and be able to have evidence against the employee in case he decided to do anything harmful to the company evidences from proxy could even later be used in court if some kind of corpoate infringment occurs due to misbehave of the employee. – PERFECT FOR COMPANY and Complete breach of User privacy and IMHO totally against European Union privacy legislation such as GDRP
4. In companies that are into the field of Aritificial Intelligence / Users behavior could even be used to advance Self-learning bots and mechanisms – NASTY ! YAECKES

…

 

3. Run SSH Socks proxy to remote SSHd server running on common SSL 443 port

 

Luckily sysadmins who were ordered the big bosses to sniff on your Web behaviour and preferences could be outsmarted with some hacks.

To protect your Browsing behaviours and Secure your privacy perhaps the best option is to use the Old but gold practice o Securing your Networkf traffic using SSH Over Proxy and SSH Dynamic tunnel as a Proxy as explained in my previous article here.

how-to-use-sshd-server-as-a-proxy-without-a-real-proxy-ssh-socks5_proxy_linux
 

In short the quest way to have your free of charge SOCKS  Remote proxy to your Home based Linux installed OS server / VPN with a Public Internet address is to use ssh as so:

 

ssh -D 3128 UserName@IP-of-Remote-SSHD-Host -p 443

 

This will start the SOCKS Proxy tunnel from Corporate Work PC to your Own Home brew server.

For some convenience it is useful to set up an .alias (for cygwin) / linux users in .bashrc file:

 

alias proxy='ssh -D 3128 UserName@IP-of-Remote-SSHD-Host -p 443';

 

To start using the Proxy from browser, I use a plugin called FoxyProxy in Chrome and Firefox browsers
set-up to connect to localhost – 127.0.0.1:3128 for All Protocols as a SOCKs v5 Proxy.

The sshd Socks proxy can be used for multiple others for example, using it you can also pass on traffic from Mail client such as Thunderbird to your Email server if you're behind a firewall prohibiting access to the common POP3 port 110 or IMAP port TCP 143. 

4. How to access SSH through Proxy using jumphost SSH hop


If you're like me and you have on your Home Linux machine only one Internet address and you have already setupped an SSL enabled service (lets say Webmail) to listen to that Public Internet IP and you don't have the possibility to run another instance of /usr/bin/sshd on port 443 via configuration or manually one time by issuing:

 

/usr/sbin/sshd -p 443

 

Then you can use another ssh another Linux server as a jump host to your own home Linux sshd server. This can be done even by purchasing a cheap VPS server for lets say 3 dollars month etc. or even better if you have a friend with another Linux home server, you can ask him to run you sshd on TCP port 443 and add you an ssh account.
Once you have the second Linux machine as JumpHost to reach out to your own machine use:

 

ssh -J Your-User@Your-jump-host.com:443 hipo@your-home-server.com -v

 

To easify this a bit long line it is handy to use some kind of alias like:

 

alias sshhome='ssh -J Your-User@Your-jump-host.com:443 hipo@your-home-server.com -v'

 

The advantage here is just by issuing this sshd tunnel and keeping it open in a terminal or setting it up as Plink Putty tunnel you have all your Web Traffic Secured
between your Work Corporate PC and your Home Brew Server, keeping the curious eyes of your Company Security Officers from your own Web traffic, hence
separating the corporate privacy from your own personal privacy. Using the just established own SSH Proxy Tunnel to home for your non-work stuff browsing habits
from the corporate systems which are accessed by switching with a button click in FoxyProxy to default proxy settings.
 

5. How to get around paranoid corporate setup where only remote access to Corporate proxy on TCP Port 80 and TCP 443 is available in Browser only

 

Using straight ssh and to create Proxy will work in most of the cases but it requires SSH access to your remote SSH running server / VPS on TCP Port 22, however under some Fort-Nox like financial involved institutions and companies for the sake of tightened security, it is common that all Outbound TCP Ports are prohibited except TCP Port 80 and SSL 443 as prior said, so what can you do then to get around this badful firewall and access the Internet via your own server Proxy? 
The hack to run SSH server either on tcp port 80 or tcp port 443 on remote Host and use 443 / 80 to acess SSHD should work, but then even for the most paranoid corporations the ones who are PCI Compliant – PCI stands for (Payment Card Industry), e.g. works with Debit and Credit Card data etc, accessing even 80 or 443  ports with something like telnet client or netcat will be impossible. 
Once connected to the corporate VPN,  this 2 two ports firewall exceptions will be only accessible via the Corporate Proxy server defined in a Web Browser (Firefox / IE / Chrome etc.) as prior explained in article.

The remedy here is to use a 3rd party tools such as httptunnel or corkscrew that  are able to TUNNEL SSH TRAFFIC VIA CORPORATE PROXY SERVER and access your own resource out of the DMZ.

Both httptunnel and corkscrew are installable both on most Linux distros or for Windows users via CygWin for those who use MobaXterm.

Just to give you better idea on what corkscrew and (hts) httptunnel does, here is Debian packages descriptions.

# apt-cache show​ corkscrew
" corkscrew is a simple tool to tunnel TCP connections through an HTTP
 proxy supporting the CONNECT method. It reads stdin and writes to
 stdout during the connection, just like netcat.
 .
 It can be used for instance to connect to an SSH server running on
 a remote 443 port through a strict HTTPS proxy.
"

 

# apt-cache show httptunnel|grep -i description -A 7
Description-en: Tunnels a data stream in HTTP requests
 Creates a bidirectional virtual data stream tunnelled in
 HTTP requests. The requests can be sent via a HTTP proxy
 if so desired.
 .
 This can be useful for users behind restrictive firewalls. If WWW
 access is allowed through a HTTP proxy, it's possible to use
 httptunnel and, say, telnet or PPP to connect to a computer
—
Description-md5: ed96b7d53407ae311a6c5ef2eb229c3f
Homepage: http://www.nocrew.org/software/httptunnel.html
Tag: implemented-in::c, interface::commandline, interface::daemon,
 network::client, network::server, network::vpn, protocol::http,
 role::program, suite::gnu, use::routing
Section: net
Priority: optional
Filename: pool/main/h/httptunnel/httptunnel_3.3+dfsg-4_amd64.deb

Windows cygwin users can install the tools with:
 

apt-cyg install –yes corkscrew httptunnel


Linux users respectively with:

apt-get install –yes corkscrew httptunnel

or 

yum install -y corkscrew httptunnel

 

You will then need to have the following configuration in your user home directory $HOME/.ssh/config file
 

Host host-addrs-of-remote-home-ssh-server.com
ProxyCommand /usr/bin/corkscrew your-corporate-firewall-rpoxy-url 8080 %h %p
 

howto-transfer-ssh-traffic-over-proxy

Picture Copyright by Daniel Haxx

The best picture on how ssh traffic is proxied is the one found on Daniel Haxx's website which is a great quick tutorial which originally helped to get the idea of how corkscrew works in proxying traffic I warmly recommend you take a quick look at his SSH Through or over Proxy article.

Host-addrs-of-remote-home-ssh-server.com could be also and IP if you don't have your own domain name in case if using via some cheap VPN Linux server with SSH, or alternatively
if you don't want to spend money on buying domain for SSH server (assuming you don't have such yet) you can use Dyn DNS or NoIP.

Another thing is to setup the proper http_proxy / https_proxy / ftp_proxy variable exports in $HOME/.bashrc in my setup I have the following:
 

export ftp_proxy="http://your-corporate-firewall-rpoxy-url:8080"
export https_proxy="https://your-corporate-firewall-rpoxy-url:8080"
export http_proxy="http://your-corporate-firewall-rpoxy-url:8080"
export HTTP_PROXY="http://your-corporate-firewall-rpoxy-url:8080"
export HTTPS_PROXY="http://your-corporate-firewall-rpoxy-url:8080"


 

6. How to Transfer Files / Data via SSH Protocol through  Proxy with SCP and SFTP


Next logical question is how to Transfer your own personal encrypted files (that contains no corporate sensitive information) between your Work laptop and home brew Linux ssh server or cheap VPN.

It took me quite a lot of try-outs until finally I got it how Secure Copy (scp) command can be used toto transfer files between my Work Computer and my Home brew server using JumpHost, here is how:
 

scp -o 'ProxyJump Username@Jumpt-Host-or-IP.com:443' ~/file-or-files-to-copy* Username@home-ssh-server.com:/path/where/to/copy/files


I love using sftp (Secure FTP) command Linux client to copy files and rarely use scp so I have a lot of try-outs to connect interacitvely via the Corporate Proxy server over a Jump-Host:443 to my Destination home machine, 

 

I've tried using netcat as it was pointed in many articles online, like so to traffic my sftp traffic via my localhost binded SSH Socks proxy on :3128 together with netcat as shown in article prior example, using following line:
 

sftp -oProxyCommand='/bin/nc -X connect -x 127.0.0.1:3128 %h %p' Username@home-ssh-server.com 22

 

Also tried proxy connect like this:

 

sftp -o ProxyCommand="proxy-connect -h localhost -p 3128 %h %p" Username@home-ssh-server.com

 

Moreover, tried to use the ssh  command (-s) argument capability to invoke SSH protocol subsystem feature which is used to facilitiate use of SSH secure transport for other application
 

ssh -v -J hipo@Jump-Host:443 -s sftp root@home-ssh-server.com -v
…

open failed: administratively prohibited: open failed

 

Finally decided to give a try to the same options arguments as in scp and thanks God it worked and I can even access via the Corporate Proxy through the Jump Host SSH interactively via Secure FTP 🙂

!! THE FINAL WORKING SFTP THROUGH PROXY VIA SSH JUMPHOST !!
 

sftp -o 'ProxyJump Username@Jumpt-Host-or-IP.com:443' Username@home-ssh-server.com


To save time from typing this long line every time, I've setup the following alias to ~/.bashrc
 

alias sftphome='sftp -o 'ProxyJump Username@Jumpt-Host-or-IP.com:443' Username@home-ssh-server.com'

 

Conclusion

Of course using own Proxy via your Home brew SSH Machine as well as transferring your data securely from your Work PC (notebook) to Home does not completely make you Surveillance free, as the Corporate Windows installed OS image is perhaps prebundled with its own integrated Keylogger as well as the Windows Domain administrators have certainly access to connect to your PC and run various commands, so this kind of Security is just an attempt to make company has less control and know less on your browsing habits and the best solution where possible to secure your privacy and separate your Personal Space form Work space by using a second computer (if having the ability to work from home) with a KVM Switch device and switch over your Work PC and Home PC via it or in some cases (where companies) allows it, setup something like VNC server (TightVNC / RealVNC) on work PC and leave it all time running in office and connect remotely with vncviewer from your own controlled secured computer.

In article I've explained shortly common scenario found in corporate Work computers proxy setup, designed to Surveil all your move, mentioned few common softwares running by default to protect from Viruses and aimed to Protect user from malicious hacking tools, explained how to view your work notebook configured Proxy, shortly mentioned on Proxy.pac and hinted how to view proxy.pac config as well as gave few of the reasons why all web traffic is being routed over central proxy.

That's all folks, Enjoy the Freedom to be less surveilled !

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Posted in Company onboarding basics, Computer Security, Hacks, Various | 3 Comments »

How to Set MySQL MariaDB server root user to be able to connect from any host on the Internet / Solution to ‘ ERROR 1045 (28000): Access denied for user ‘root’@’localhost’ (using password: YES) ‘

Tuesday, September 3rd, 2019

How-to-set-up-MariaDB-server-root-admin-user-to-be-able-to-connect-from-any-host-anywhere-mariadb-seal-logo-picture

In this small article, I'll shortly explain on how I setup a Standard default package MariaDB Database server on Debian 10 Buster Linux and how I configured it to be accessible from any hostname on the Internet in order to make connection from remote Developer PC with MySQL GUI SQL administration tools such as MySQL WorkBench / HeidiSQL / Navicat / dbForge   as well as the few set-backs experienced in the process (e.g. what was the reason for ' ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES) '  error and its solution.

Setting new or changing old MariaDB (MySQL) root server password

 

I've setup a brand new MariaDB database (The new free OpenSource software fork of MySQL) mariadb-server-10.3 on a Debian 10, right after the OS was installed with the usual apt command:

# apt install mariadb-server

Next tep was to change the root access password which was set to empty pass by default, e.g. connected with mysql CLI locally while logged via SSH on server and run:

MariaDB [(none)]> mysql -u root -p

use mysql;
update user set authentication_string=PASSWORD("MyChosenNewPassword") where User='root';

There was requirement by the customer, that MySQL server is not only accessed locally but be accessed from any IP address from anywhere on the Internet, so next step was to do so.

Allowing access to MySQL server from Anywhere

Allowing access from any host to MariaDB SQL server  is a bad security practice but as the customer is the King I've fulfilled this weird wish too, by changing the listener for MariaDB (MySQL) on Debian 10 codenamed Buster
 changing the default listener
to be not the default 127.0.0.1 (localhost) but any listener is done by modifying the bind-address directive in conf /etc/mysql/mariadb.conf.d/50-server.cnf:

root@linux:~# vim /etc/mysql/mariadb.conf.d/50-server.cnf

Then comment out

bind-address  = 127.0.0.1

and  add instead 0.0.0.0 (any listener)

 

bind-address  = 0.0.0.0
root@linux:/etc/mysql/mariadb.conf.d# grep -i bind-address 50-server.cnf
##bind-address            = 127.0.0.1
bind-address    = 0.0.0.0


Then to make the new change effective restart MariaDB (luckily still using the old systemV init script even though systemd is working.
 

root@linux:~# /etc/init.d/mysql restart
[ ok ] Restarting mysql (via systemctl): mysql.service.


To make sure it is properly listening on MySQL defaults TCP port 3306, then as usual used netcat.

root@pritchi:~# netstat -etna |grep -i 3306
tcp        0      0 0.0.0.0:3306            0.0.0.0:*               LISTEN      109        1479917  

 

By the way the exact mariadb.cnf used on this middle-sized front-backend server is here – the serveris planned to be a Apache Web server + Database host with MySQL DB of a middle range to be able to serve few thousand of simultaneous unique customers.

To make sure no firewall is preventing MariaDB to be accessed, I've checked for any reject rules iptables and ipset definitions, e.g.:
 

root@linux:~# iptables -L |gre -i rej
…
root@linux:~# ipset list
…

 

Then to double make sure the MySQL is allowed to access from anywhere, used simple telnet from my Desktop Laptop PC (that also runs Debian Linux) towards the server .

hipo@jeremiah:~$ telnet 52.88.235.45 3306
Trying 52.88.235.45…
Connected to 52.88.235.45.
Escape character is '^]'.
[
5.5.5-10.3.15-MariaDB-1
                       rQ}Cs>v\��-��G1[W%O>+Y^OQmysql_native_password
Connection closed by foreign host.

 

As telnet is not supporting the data encryption after TCP proto connect, in a few seconds time, remote server connection is terminated.

 

Setting MySQL user to be able to connect to local server MySQL from any remote hostname


I've connected locally to MariaDB server with mysql -u root -p and issued following set of SQL commands to make MySQL root user be able to connect from anywhere:

 

CREATE USER 'root'@'%' IDENTIFIED BY 'my-secret-pass';
GRANT ALL ON *.* TO 'root'@'localhost';
GRANT ALL ON *.* TO 'root'@'%';

 

Next step, I've took was to try logging in with root (admin) MariaDB superuser from MySQL CLI (Command Line Interface) on my desktop just to find out, I'm facing a nasty error.
 

hipo@jeremiah:~$ mysql -u root -H remote-server-hostname.com -p
Enter password:
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)


My first guess was something is wrong with my root user created in MySQL's mysql.user table (In MySQL this is the privileges table that stores, how MySQL user credentials are handled by mysqld local OS running process.

 

Changing the MySQL root (admin) password no longer possible on Debian 10 Buster?

 

The standard way ot change the MySQL root password well known via a simple dpkg-reconfigure (provided by Debian's debconf is no longer working so below command produces empty output instead of triggering the good old Ncurses text based interface well-known over the years …

 

root@linux:~# /usr/sbin/dpkg-reconfigure mariadb-server-10.3
…
 

 

Viewing MariaDB (MySQL) username / password set-up from the CLI

 

To list how this set-privileges looked like I've used following command:

 

MariaDB [mysql]> select * from mysql.user where User = 'root';
+———–+——+——————————————-+————-+————-+————-+————-+————-+———–+————-+—————+————–+———–+————+—————–+————+————+————–+————+———————–+——————+————–+—————–+——————+——————+—————-+———————+——————–+——————+————+————–+————————+———————+———-+————+————-+————–+—————+————-+—————–+———————-+———————–+———————–+——————+———+————–+——————–+
| Host      | User | Password                                  | Select_priv | Insert_priv | Update_priv | Delete_priv | Create_priv | Drop_priv | Reload_priv | Shutdown_priv | Process_priv | File_priv | Grant_priv | References_priv | Index_priv | Alter_priv | Show_db_priv | Super_priv | Create_tmp_table_priv | Lock_tables_priv | Execute_priv | Repl_slave_priv | Repl_client_priv | Create_view_priv | Show_view_priv | Create_routine_priv | Alter_routine_priv | Create_user_priv | Event_priv | Trigger_priv | Create_tablespace_priv | Delete_history_priv | ssl_type | ssl_cipher | x509_issuer | x509_subject | max_questions | max_updates | max_connections | max_user_connections | plugin                | authentication_string | password_expired | is_role | default_role | max_statement_time |
+———–+——+——————————————-+————-+————-+————-+————-+————-+———–+————-+—————+————–+———–+————+—————–+————+————+————–+————+———————–+——————+————–+—————–+——————+——————+—————-+———————+——————–+——————+————+————–+————————+———————+———-+————+————-+————–+—————+————-+—————–+———————-+———————–+———————–+——————+———+————–+——————–+
| localhost | root | *E6D338325F50177F2F6A15EDZE932D68C88B8C4F | Y           | Y           | Y           | Y           | Y           | Y         | Y           | Y             | Y            | Y         | Y          | Y               | Y          | Y          | Y            | Y          | Y                     | Y                | Y            | Y               | Y                | Y                | Y              | Y                   | Y                  | Y                | Y          | Y            | Y                      | Y                   |          |            |             |              |             0 |           0 |               0 |                    0 | mysql_native_password |                       | N                | N       |              |           0.000000 |
| %         | root | *E6D338325F50177F2F6A15EDZE932D68C88B8C4F | Y           | Y           | Y           | Y           | Y           | Y         | Y           | Y             | Y            | Y         | N          | Y               | Y          | Y          | Y            | Y          | Y                     | Y                | Y            | Y               | Y                | Y                | Y              | Y                   | Y                  | Y                | Y          | Y            | Y                      | Y                   |          |            |             |              |             0 |           0 |               0 |                    0 |                       |                       | N                | N       |              |           0.000000 |
+———–+——+——————————————-+————-+————-+————-+————-+————-+———–+————-+—————+————–+———–+————+—————–+————+————+————–+————+———————–+——————+————–+—————–+——————+——————+—————-+———————+——————–+——————+————+————–+————————+———————+———-+————+————-+————–+—————+————-+—————–+———————-+———————–+———————–+——————+———+————–+——————–+

 

The hashed (encrypted) password string is being changed from the one on the server, so please don't try to hack me (decrypt it) 🙂
As it is visible from below output the Host field for root has the '%' string which means, any hostname is authorized to be able to connect and login to the MySQL server, so this was not the problem.

After quite some time on reading on what causes
' ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES) ',
I've spend some time reading various forum discussions online on the err such as the one on StackOverflow here SuperUser.com's  how to fix access denied for user 'root'@'localhost' and one on askubuntu.com's – ERROR 1045(28000) : Access denied for user 'root@localhost' (using password: no ) and after a while finally got it, thanks to a cool IRC.FREENODE.NET guy nicknamed, hedenface who pointed me I'm that, I'm trying to use the -H flag (Prodice HTML) instead of -h (host_name), it seems somehow I ended up with the wrong memory that the -H stands for hostname, by simply using -h I could again login Hooray!!!

 

root@linux:~$ mysql -u root -h remote-server-host.com -p
Enter password:
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 14
Server version: 10.3.15-MariaDB-1 Debian 10

 

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.


I've further asked the customer to confirm, he can connect also from his Microsoft Windows 10 PC situated on a different LAN network and got his confirmation. Few notes to make here is I've also installed phpmyadmin on the server using phpmyadmin php source code latest version, as in Debian 10 it seems the good old PHP is no longer available (as this crazy developers again made a mess and there is no phpmyadmin .deb package in Debian Buster – but that's a different story I'll perhaps try to document in some small article in future.

Tags: , , , , , , , , , , ,
Posted in MySQL, Remote System Administration | No Comments »

Howto debug and remount NFS hangled filesystem on Linux

Monday, August 12th, 2019

nfsnetwork-file-system-architecture-diagram

If you're using actively NFS remote storage attached to your Linux server it is very useful to get the number of dropped NFS connections and in that way to assure you don't have a remote NFS server issues or Network connectivity drops out due to broken network switch a Cisco hub or other network hop device that is routing the traffic from Source Host (SRC) to Destination Host (DST) thus, at perfect case if NFS storage and mounted Linux Network filesystem should be at (0) zero dropped connectios or their number should be low. Firewall connectivity between Source NFS client host and Destination NFS Server and mount should be there (set up fine) as well as proper permissions assigned on the server, as well as the DST NFS should be not experiencing I/O overheads as well as no DNS issues should be present (if NFS is not accessed directly via IP address).
In below article which is mostly for NFS novice admins is described shortly few of the nuances of working with NFS.
 

1. Check nfsstat and portmap for issues

One indicator that everything is fine with a configured NFS mount is the number of dropped NFS connections
or with a very low count of dropped connections, to check them if you happen to administer NFS

nfsstat

 

linux:~# nfsstat -o net
Server packet stats:
packets    udp        tcp        tcpconn
0          0          0          0  


nfsstat is useful if you have to debug why occasionally NFS mounts are getting unresponsive.

As NFS is so dependent upon portmap service for mapping the ports, one other point to check in case of Hanged NFSes is the portmap service whether it did not crashed due to some reason.

 

linux:~# service portmap status
portmap (pid 7428) is running…   [portmap service is started.]

 

linux:~# ps axu|grep -i rpcbind
_rpc       421  0.0  0.0   6824  3568 ?        Ss   10:30   0:00 /sbin/rpcbind -f -w


A useful commands to debug further rcp caused issues are:

On client side:

 

rpcdebug -m nfs -c

 

On server side:

 

rpcdebug -m nfsd -c

 

It might be also useful to check whether remote NFS permissions did not changed with the good old showmount cmd

linux:~# showmount -e rem_nfs_server_host


Also it is useful to check whether /etc/exports file was not modified somehow and whether the NFS did not hanged due to attempt of NFS daemon to reload the new configuration from there, another file to check while debugging is /etc/nfs.conf – are there group / permissions issues as well as the usual /var/log/messages and the kernel log with dmesg command for weird produced NFS client / server or network messages.

nfs-utils disabled serving NFS over UDP in version 2.2.1. Arch core updated to 2.3.1 on 21 Dec 2017 (skipping over 2.2.1.) If UDP stopped working then, add udp=y under [nfsd] in /etc/nfs.conf. Then restart nfs-server.service.

If the remote NFS server is running also Linux it is useful to check its /etc/default/nfs-kernel-server configuration

At some stall cases it might be also useful to remount the NFS (but as there might be a process on the Linux server) trying to read / write data from the remote NFS mounted FS it is a good idea to check (whether a process / service) on the server is not doing I/O operations on the NFS and if such is existing to kill the process in question with fuser
 

linux:~# fuser -k [mounted-filesystem]
 

 

2. Diagnose the problem interactively with htop


    Htop should be your first port of call. The most obvious symptom will be a maxed-out CPU.
    Press F2, and under "Display options", enable "Detailed CPU time". Press F1 for an explanation of the colours used in the CPU bars. In particular, is the CPU spending most of its time responding to IRQs, or in Wait-IO (wio)?
 

3. Get more extensive Mount info with mountstats

 

nfs-utils package contains mountstats command which is very useful in debugging further the issues identified

$ mountstats
Stats for example:/tank mounted on /tank:
  NFS mount options: rw,sync,vers=4.2,rsize=524288,wsize=524288,namlen=255,acregmin=3,acregmax=60,acdirmin=30,acdirmax=60,soft,proto=tcp,port=0,timeo=15,retrans=2,sec=sys,clientaddr=xx.yy.zz.tt,local_lock=none
  NFS server capabilities: caps=0xfbffdf,wtmult=512,dtsize=32768,bsize=0,namlen=255
  NFSv4 capability flags: bm0=0xfdffbfff,bm1=0x40f9be3e,bm2=0x803,acl=0x3,sessions,pnfs=notconfigured
  NFS security flavor: 1  pseudoflavor: 0

 

NFS byte counts:
  applications read 248542089 bytes via read(2)
  applications wrote 0 bytes via write(2)
  applications read 0 bytes via O_DIRECT read(2)
  applications wrote 0 bytes via O_DIRECT write(2)
  client read 171375125 bytes via NFS READ
  client wrote 0 bytes via NFS WRITE

RPC statistics:
  699 RPC requests sent, 699 RPC replies received (0 XIDs not found)
  average backlog queue length: 0

READ:
    338 ops (48%)
    avg bytes sent per op: 216    avg bytes received per op: 507131
    backlog wait: 0.005917     RTT: 548.736686     total execute time: 548.775148 (milliseconds)
GETATTR:
    115 ops (16%)
    avg bytes sent per op: 199    avg bytes received per op: 240
    backlog wait: 0.008696     RTT: 15.756522     total execute time: 15.843478 (milliseconds)
ACCESS:
    93 ops (13%)
    avg bytes sent per op: 203    avg bytes received per op: 168
    backlog wait: 0.010753     RTT: 2.967742     total execute time: 3.032258 (milliseconds)
LOOKUP:
    32 ops (4%)
    avg bytes sent per op: 220    avg bytes received per op: 274
    backlog wait: 0.000000     RTT: 3.906250     total execute time: 3.968750 (milliseconds)
OPEN_NOATTR:
    25 ops (3%)
    avg bytes sent per op: 268    avg bytes received per op: 350
    backlog wait: 0.000000     RTT: 2.320000     total execute time: 2.360000 (milliseconds)
CLOSE:
    24 ops (3%)
    avg bytes sent per op: 224    avg bytes received per op: 176
    backlog wait: 0.000000     RTT: 30.250000     total execute time: 30.291667 (milliseconds)
DELEGRETURN:
    23 ops (3%)
    avg bytes sent per op: 220    avg bytes received per op: 160
    backlog wait: 0.000000     RTT: 6.782609     total execute time: 6.826087 (milliseconds)
READDIR:
    4 ops (0%)
    avg bytes sent per op: 224    avg bytes received per op: 14372
    backlog wait: 0.000000     RTT: 198.000000     total execute time: 198.250000 (milliseconds)
SERVER_CAPS:
    2 ops (0%)
    avg bytes sent per op: 172    avg bytes received per op: 164
    backlog wait: 0.000000     RTT: 1.500000     total execute time: 1.500000 (milliseconds)
FSINFO:
    1 ops (0%)
    avg bytes sent per op: 172    avg bytes received per op: 164
    backlog wait: 0.000000     RTT: 2.000000     total execute time: 2.000000 (milliseconds)
PATHCONF:
    1 ops (0%)
    avg bytes sent per op: 164    avg bytes received per op: 116
    backlog wait: 0.000000     RTT: 1.000000     total execute time: 1.000000 (milliseconds)


nfs-utils disabled serving NFS over UDP in version 2.2.1. Arch core updated to 2.3.1 on 21 Dec 2017 (skipping over 2.2.1.) If UDP stopped working then, add udp=y under [nfsd] in /etc/nfs.conf. Then restart nfs-server.service.
 

4. Check for firewall issues
 

If all fails make sure you don't have any kind of firewall issues. Sometimes firewall changes on remote server or somewhere in the routing servers might lead to stalled NFS mounts.

 

To use properly NFS as you should know as a minimum you need to have opened as ports is Port 111 (TCP and UDP) and 2049 (TCP and UDP) on the NFS server (side) as well as any traffic inspection routers on the road from SRC (Linux client host) and NFS Storage destination DST server.

There are also ports for Cluster and client status (Port 1110 TCP for the former, and 1110 UDP for the latter) as well as a port for the NFS lock manager (Port 4045 TCP and UDP) but having this opened or not depends on how the NFS is configured. You can further determine which ports you need to allow depending on which services are needed cross-gateway.
 

5. How to Remount a Stalled unresponsive NFS filesystem mount

 

At many cases situation with remounting stalled NFS filesystem is not so easy but if you're lucky a standard mount and remount should do the trick.

Most simple way to remout the NFS (once you're sure this might not disrupt any service) – don't blame me if you break something is with:
 

umount -l /mnt/NFS_mnt_point
mount /mnt/NFS_mnt_point


Note that the lazy mount (-l) umount opt is provided here as very often this is the only way to unmount a stalled NFS mount.

Sometimes if you have a lot of NFS mounts and all are inacessible it is useful to remount all NFS mounts, if the remote NFS is responsive this should be possible with a simple for bash loop:

for P in $(mount | awk '/type nfs / {print $3;}'); do echo $P; echo "sudo umount $P && sudo mount $P" && echo "ok :)"; done


If you cd /mnt/NFS_mnt_point and try ls and you get

$ ls
.: Stale File Handle

 

You will need to unmount the FS with forceful mount flag

umount -f /mnt/NFS_mnt_point
 

Sum it up


In this article, I've shown you a few simple ways to debug what is wrong with a Stalled / Hanged NFS filesystem present on a NFS server mounted on a Linux client server.
Above was explained the common issues caused by NFS portmap (rpcbind) dependency, how to its status is fine, some further diagnosis with htop and mountstat was pointed. I've pointed the minimum amount of TCP / UDP ports 2049 and 111 that needs to be opened for the NFS communication to work and finally explained on how to remount a stalled NFS single or all attached mount on a NFS client to restore to normal operations.
As NFS is a whole ocean of things and the number of ways it is used are too extensive this article is just a general info useful for the NFS dummy admin for more robust configs read some good book on NFS such as Managing NFS and NIS, 2nd Edition – O'Reilly Media and for Kernel related NFS debugging make sure you check as a minimum ArchLinux's NFS troubleshooting guide and sourceforge's NFS Troubleshoting and Optimizing NFS Performance guides.

 

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Posted in Linux, NFS, Storage | No Comments »

Howto create Linux Music Audio CD from MP3 files / Create playable WAV format Audio CD Albums from MP3s

Tuesday, July 16th, 2019

cdburning-audio-music-cd-from-mp3-on-linuxcomapct-disc-tux-linux-logo

Recently my Mother asked me to prepare a Music Audio CD for her from a popular musician accordionist Stefan Georgiev from Dobrudja who has a unique folklore Bulgarian music.

As some of older people who still remember the age of the CD and who had most likely been into the CD burning Copy / Piracy business so popular in the countries of the ex-USSR so popular in the years 1995-2000 audio ,  Old CD Player Devices were not able to play the MP3 file format due to missing codecs (as MP3 was a proprietary compression that can't be installed on every device without paying the patent to the MP3 compression rights holder.

The revolutionary MP3 compression used to be booming standard for transferring Music data due to its high compression which made an ordinary MP3 of 5 minutes of 5MB (10+ times more compression than an ordinary classic WAV Audio the CPU intensiveness of MP3 files that puts on the reading device, requiring the CD Player to have a more powerful CPU.

Hence  due to high licensing cost and requirement for more powerful CPU enabled Audio Player many procuders of Audio Players never introduced MP3 to their devices and MP3 Neve become a standard for the Audio CD that was the standard for music listening inside almost every car out there.

Nowdays it is very rare need to create a Audio CD as audio CDs seems to be almost dead (As I heard from a Richard Stallman lecture In USA nowadays there is only 1 shop in the country where you can still buy CD or DVD drives) and only in third world as Africa Audio CDs perhaps are still in circulation.

Nomatter that as we have an old Stereo CD player on my village and perhaps many others, still have some old retired CD reading devices being able to burn out a CD is a useful thing.

Thus to make mother happy and as a learning excercise, I decided to prepare the CD for her on my Linux notebook.
Here I'll shortly describe the takes I took to make it happen which hopefully will be useful for other people that need to Convert and burn Audio CD from MP3 Album.

 

1. First I downloaded the Album in Mp3 format from Torrent tracker

My homeland Bulgaria and specific birth place place the city of Dobrich has been famous its folklore:  Galina Durmushlijska and Stefan Georgiev are just 2 of the many names along with Оркестър Кристал (Orchestra Crystal) and the multitude of gifted singers. My mother has a santiment for Stefan Georgiev, as she listened to this gifted accordinist on her Uncle's marriage.

Thus In my case this was (Стефан Георгиев Хора и ръченици от Добруджа) the album full song list here If you're interested to listen the Album and Enjoy unique Folklore from Dobrudja (Dobrich) my home city, Stefan Georgiev's album Hora and Rachenica Dances is available here

 


Stefan_Georgiev-old-audio-Music-CD-Hora-i-Rychenici-ot-Dobrudja-Horos-and-Ruchenitsas-from-Dobrudja-CD_Cover
I've downloaded them from Bulgarian famous torrent tracker zamunda.net in MP3 format.
Of course you need to have a CD / DVD readed and write device on the PC which nowdays is not present on most modern notebooks and PCs but as a last resort you can buy some cheap External Optical CD / DVD drive for 25 to 30$ from Amazon / Ebay etc.

 

2. You will need to install a couple of programs on Linux host (if you don't have it already)


To be able to convert from command line from MP3 to WAV you will need as minimum ffmpeg and normalize-audio packages as well as some kind of command line burning tool like cdrskin  wodim which is
the fork of old good known cdrecord, so in case if you you're wondering what happened with it just
use instead wodim.

Below is a good list of tools (assuming you have enough HDD space) to install:

 

root@jeremiah:/ # apt-get install –yes dvd+rw-tools cdw cdrdao audiotools growisofs cdlabelgen dvd+rw-tools k3b brasero wodim ffmpeg lame normalize-audio libavcodec58

 

Note that some of above packages I've installed just for other Write / Read operations for DVD drives and you might not need that but it is good to have it as some day in future you will perhaps need to write out a DVD or something.
Also the k3b here is specific to KDE and if you're a GNOME user you could use Native GNOME Desktop app such brasero or if you're in a more minimalistic Linux desktop due to hardware contrains use XFCE's native xfburn program.

If you're a console / terminal geek like me you will definitely enjoy to use cdw
 

root@jeremiah:/ # apt-cache show cdw|grep -i description -A 1
Description-en: Tool for burning CD's – console version
 Ncurses-based frontend for wodim and genisoimage. It can handle audio and
—
Description-md5: 77dacb1e6c00dada63762b78b9a605d5
Homepage: http://cdw.sourceforge.net/

 

3. Selecting preferred CD / DVD / BD program to use to write out the CD from Linux console


cdw uses wodim (which is a successor of good old known console cdrecord command most of use used on Linux in the past to burn out new Redhat / Debian / different Linux OS distro versions for upgrade purposes on Desktop and Server machines.

To check whether your CD / DVD drive is detected and ready to burn on your old PC issue:

 

root@jeremiah:/# wodim -checkdrive
Device was not specified. Trying to find an appropriate drive…
Detected CD-R drive: /dev/cdrw
Using /dev/cdrom of unknown capabilities
Device type    : Removable CD-ROM
Version        : 5
Response Format: 2
Capabilities   :
Vendor_info    : 'HL-DT-ST'
Identification : 'DVDRAM GT50N    '
Revision       : 'LT20'
Device seems to be: Generic mmc2 DVD-R/DVD-RW.
Using generic SCSI-3/mmc   CD-R/CD-RW driver (mmc_cdr).
Driver flags   : MMC-3 SWABAUDIO BURNFREE
Supported modes: TAO PACKET SAO SAO/R96P SAO/R96R RAW/R16 RAW/R96P RAW/R96R

You can also use xorriso (whose added value compared to other console burn cd tools is is not using external program for ISO9660 formatting neither it use an external or an external burn program for CD, DVD or BD (Blue Ray) drive but it has its own libraries incorporated from libburnia-project.org libs.

Below output is from my Thinkpad T420 notebook. If the old computer CD drive is there and still functional in most cases you should not get issues to detect it.

cdw ncurses text based CD burner tool's interface is super intuitive as you can see from below screenshot:

cdw-burn-cds-from-console-terminal-on-GNU-Linux-and-FreeBSD-old-PC-computer

CDW has many advanced abilities such as “blanking” a disk or ripping an audio CD on a selected folder. To overcome the possible problem of CDW not automatically detecting the disk you have inserted you can go to the “Configuration” menu, press F5 to enter the Hardware options and then on the first entry press enter and choose your device (by pressing enter again). Save the setting with F9.
 

4. Convert MP3 / MP4 Files or whatever format to .WAV to be ready to burn to CD


Collect all the files you want to have collected from the CD album in .MP3 a certain directory and use a small one liner loop to convert files to WAV with ffmpeg:
 

cd /disk/Music/Mp3s/Singer-Album-directory-with-MP3/

for i in $( ls *.mp3); do ffmpeg -i $i $i.wav; done


If you don't have ffmpeg installed and have mpg123 you can also do the Mp3 to WAV conversion with mpg123 cmd like so:

 

for i in $( ls ); do mpg123 -w $i.wav $i.mp3; done


Another alternative for conversion is to use good old lame (used to create Mp3 audio files but abling to also) decode
mp3 to wav.

 

lame –decode somefile.mp3 somefile.wav


In the past there was a burn command tool that was able to easily convert MP3s to WAV but in up2date Linux modern releases it is no longer available most likely due to licensing issues, for those on older Debian Linux 7 / 8 / 9 / Ubuntu 8 to 12.XX / old Fedoras etc. if you have the command you can install burn and use it (and not bother with shell loops):

apt-get install burn

or

yum install burn
…


Once you have it to convert

 

$ burn -A -a *.mp3
 

 

5. Fix file naming to remove empty spaces such as " " and substitute to underscores as some Old CD Players are
unable to understand spaces in file naming with another short loop.

 

for f in *; do mv "$f" `echo $f | tr ' ' '_'`; done

 

6. Normalize audio produced .WAV files (set the music volume to a certain level)


In case if wondering why normalize audio is needed here is short extract from normalize-audio man page command description to shed some light.

"normalize-audio  is  used  to  adjust  the volume of WAV or MP3 audio files to a standard volume level.  This is useful for things like creating mp3 mixes, where different recording levels on different albums can cause the volume to  vary  greatly from song to song."
 

cd /disk/Music/Mp3s/Singer-Album-directory-with-MP3/

normalize-audio -m *.wav

 

7. Burn the produced normalized Audio WAV files to the the CD

 

wodim -v -fix -eject dev='/dev/sr0' -audio -pad *.wav


Alternatively you can conver all your MP3 files to .WAV with anything be it audacity
or another program or even use 
GNOME's CDBurn tool brasero (if gnome user) or KDE's CDBurn which in my opinion is
the best CD / DVD burning application for Linux K3B.

Burning Audio CD with K3b is up to few clicks and super easy and even k3b is going to handle the MP3 to WAV file Conversion itself. To burn audio with K3B just run it and click over 'New Audio CD Project'.

k3b-on-debian-gnu-linux-burn-audio-cd-screenshot

For those who want to learn a bit more on CD / DVD / Blue-Ray burning on GNU / Linux good readings are:
Linux CD Burning Mini Howto, is Linux's CD Writing Howto on ibiblio (though a bit obsolete) or Debian's official documentation on BurnCD.
 

8. What we learned here


Though the accent of this tutorial was how to Create Audio Music CD from MP3 on GNU / Linux, the same commands are available in most FreeBSD / NetBSD / OpenBSD ports tree so you can use the same method to build prepare Audio Music CD on *BSDs.

In this article, we went through few basic ways on how to prepare WAV files from MP3 normalize the new created WAV files on Linux, to prepare files for creation of Audio Music CD for the old mom or grandma's player or even just for fun to rewind some memories. For GUI users this is easily done with  k3b,  brasero or xfburn.

I've pointed you to cdw a super useful text ncurses tool that makes CD Burninng from plain text console (on servers) without a Xorg / WayLand  GUI installed super easy. It was shortly reviewed what has changed over the last few years and why and why cdrecord was substituted for wodim. A few examples were given on how to handle conversion through bash shell loops and you were pointed to some extra reading resources to learn a bit more on the topic.
There are plenty of custom scripts around for doing the same CD Burn / Covnersion tasks, so pointing me to any external / Shell / Perl scripts is mostly welcome.

Hope this learned you something new, Enjoy ! 🙂

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Posted in File Convert Tools, Linux, Linux and FreeBSD Desktop, Various | No Comments »

Play the Dangerous Dave old arcade classic on iPhone, iPad and Android Smartphone – Dangerous Dave 1990’s computer arcade classic Mario like game phone Application

Thursday, April 27th, 2017

Dangerous_Dave_1990-entry-game-screen-computer-mario-like-game

I still remember the good old times with my 16 Bit Desktop Personal Computer Parvetz 8086 CPU where one of the most favourite games I used to play a computer substitute for Mario for DOS operation system was Dangerous Dave 2 (DDAVE.EXE) an arcade game classic game from the distant year 1990 authored by a whiz kid which later become world famous Computer game Programmer John Romero mostly known for being a cofounder of Game creation comppany ID Software  which authored the 3D Shooter genesis classics such as Wolfenstein 3D, Spear of Destiny, DOOM I and DOOM II HeXen I / II, QUAKE I,  QUAKE II, QUAKE II as well as some absolute arcade classics as Commander Keen 4 🙂

As John Romero shared himsef the game is actually inspired by Super Mario Bros so he decided to create a kinda of computer remake of the game in his teenage years and he did a great job yeah 🙂

There are similarities between Super Mario and Dangerous Dave as both have  the secret levels, the level design, the monsters, and the jump all around collecting cups with a final aim to end up in the level exit door.

The game was originally developed for Apple II and later reworked and ported to DOS and because of it is immerse popularity Dave 2, 3 and 4 come out short

The game is really awesome and worths all praise, I was nicely surprised to find out Dangerous Dave amazing game is available for Iphone 5, 5S and Iphone 6 right into Appstore

Here is the awesome Dangerous DAVE Iphone port description:

"Dave is a redneck on a rampage to reclaim his stolen trophies from the town bully, Clyde! Dangerous Dave is back in his classic adventure in the Deserted Pirate's Hideout. This recreation of the original 1990 DOS game is just as action-packed and difficult as the original! There are only 10 levels, but, wow, are they hard. "

Dangerous_Dave-level-2-computer-Mario-like-old-arcade-game-classic

I have to say the game controls are pretty much amazing and the game controls even though reimplemented on the Iphone touch screen device are truly amazing so gameplay resembles pretty much the Computer original game keyboard controls and in a sense the touch screen controls are a little bit more convenient.

The iOS Dave port is pretty nice and updated version is also available which is possible to be chosen on Game entry screen so you either play classic mode or you play the Dave in the Deserted pirated hideout updated version and sound Dave remake, below is a screenshot of the updated GUI version:

Dangerous_Dave-in-the-deserted-pirate-hideout-updated-dave-gui-mario-like-computer-arcade-classic-game

Dave in the deserted pirate hideout Updated GUI shot by Alfonso Romero – level 1

Dangerous_Dave_mario-like-computer-classic-arcade-jump-and-run-ios-dave-in-the-deserted-pirates-hideout

Dave in the deserted pirate hideout Updated GUI shot by Alfonso Romero – level 2

Dangerous_Dave_Computer_like_Mario-high-level-computer-classic-arcade==

Actually Dangerous Dave is also available for Android Smartphone devices even though the controllers suck a lot compared to the Iphone version if you happen to own an Android OS phone check here 

For those who don't own an Iphone or Android SmartPhone (lucky you) you can also play Dangerous Dave online via DOSBox Web emulation from this URL

Dangerous_Dave-computer-classic-game-now-for-iphone-level5-screenshot

For those who prefer to play Dangerous Dave as a standalone desktop application as in the good old times on Windows 7 / 8, 8.1 and Windows 10 both on 32 and 64 bits platform you can download it (as of moment of writting article) from here

A mirrored version of Dangerous Dave for Windows 7/8/10 on www.pc-freak.net in case if it disappears in future check here.

Our generation people born in 1983-1986 who are now about 33 years old has grown up with this game and I'm pretty sure if you happen to be one of those people will truly enjoy to replay the quick 10 game levels and remind the fuzzy computer arcade games age when every growing kid like me was obsessed with the idea to play and complete as much as games possible with countless nights in front of the Green and Black screen and later on SVGA screens geeking on and on loosing idea of time and space and being completely sunk by the game.

Dangerous_Dave_Level-9-classic-old-school-arcade-mario-like-game

Happy gaming ! 🙂

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Posted in Arcade Games, Curious Facts, Entertainment, Everyday Life, Mobile Phone Apps & Games, Various | 1 Comment »

Remove string line from file on Linux and BSD – Delete entire line with string from file

Tuesday, March 15th, 2016

linux-remove-lines-containing-string-with-sed

If you're already used too using grep -v "sometring" filename to print everything from a file without the certain grepped string output and you want to do the same to delete lines based on strings without having to output the grepped string to a file and then overwritting the original file:
 

grep -v 'whatever' filename > filename1
mv filename1 filename


A much better way to delete an whole line containing a string match from a file is to use sed
sed should be the tool of choice especially if you're scripting because sed is especially made for such batch edittings.

Here is how to do delete an entire line based on a given string:

 

sed –in-place '/some string to search and delete/d' myfilename


It might be a good idea to also create backups just to make sure something doesn't get deleted incidently to do use:

sed –in-place=.bak '/some string to search and delete/d' myfilename

If you need to wipe out an exact string from all files within a folder you might use a for loop or perl (some good examples check my previous article here)

In short to use bash's for loop here is how to backup and remove all lines with a string match within all files within a Linux directory:

 

for f in *.txt; do sed –in-place '/some string/d'
"$f"; done
find -name '*.txt' -exec sed –in-place=.bak '/some
string/d' "{}" ';'

 

BTW SED is really rich editor and some people got so much into it that there is even a sed written text (console) version of arkanoid 🙂

sed-text-editor-written-arkanoid-game-linux-bsd

If you want to break the ice and get some fun in your boring sysadmin life get sed arkanoid code from here.
I have it installed under pc-freak.net free ASCII Games entertainment service, so if you want to give it a try just login and give a try.

Enjoy 🙂

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Posted in Linux, Remote System Administration, System Administration, Various | No Comments »

Use mac PC built-in camera to make / take pictures on Mac OS X macbookair notebook with Photo Booth

Friday, February 26th, 2016

take-picture-or-video-with-built-in-camera-on-MacOSX-PhotoboothLOGO

It seems we lost our Good high quality Digital Camera somewhere and I was in need urgently to make a good quality photo (my ZTE Phone) has a very bad camera, so I got the idea to use Macbookair's camera as it has better
resolution to picture my present a  Tank Tort 🙂 hand made by my wife as a present for the Day of the Defender of the Fatherland which is a major feast in Russia, Belarus and many of the ex-Soviet Union members communist countries.

Actually using build in camare in MacBookAir is a handy thing for people mising at the moment a good high quality digital camera as it is thin and light and build in MacBook cam can be used to make Videos and Pictures exactly the same way
as an ordinary Tablet Computer is used so commonly nowadays by many:

In other words I needed for the Mac OS X equivalent to Cheese's (Photo and Video) capturer program for Linux.

Luckily for people interested in using their Mac OS notebook as a amateur camera this is easy by using default shipped Mac Application called:

Photo Booth app

To Launch Photo Booth app it just look it up in Finder and double click it:

PhotoBooth-how-to-take-photos-on-macosx

Clicking the large red button underneath the preview area will take a picture after an optional countdown.

Tort Tank of Svetka

Besides being able to capture Video and Pictures from Mac's camera it could add also some nice effects to taken pictures and videos (supports a basic video editing) features and effects.

The effects you can choose are are: Sepia, Black and White, Glow, Comic Book, Normal, Colored Pencil, Thermal Camera, X-Ray, and Pop Art. There are also effects that change the person in the picture using these effects: Bulge, Dent, Twirl, Squeeze, Mirror, Light Tunnel, Fish Eye, and Stretch. Actually  photographic filters of Photo Booth are very similar to Adobe Photoshop.

make-picture-on-mac-photobooth-effects-screenshot
By default Photo Booth will create picture, howver

Photo Booth saves your photos as JPEG files in a folder named Photo Booth, located in your home folder.

Choose File > Reveal in Finder

to see your picture files.

A much better way to be able to easily see and access all taken Pictures and Videos with Photo Booth is to

 

open Terminal

 

and type:

——-
 

 

$ cd Pictures
$ ln -s Photo\ Booth\ Library/Pictures/ PhotoBoothPics


This will make Link to pictures be easily accessible from your Finder -> Pictures folder
 
Applying custom photo backgrounds

A very useful feature of Photo Booth is that the user can apply backdrops to provide an effect similar to a green screen. When a backdrop is selected, a message appears telling the user to step away from the camera. Once the background is analyzed, the user steps back in front of the camera and is shown in front of the chosen backdrop.

For people who prefer to take photos using a console program on Mac OS I guess you should take a look at ffpeg
Here is one more snapshot of the Tort Tank snapshot made with the Macbookair of Svetlana 🙂

Tort Tank


P.S. If you like the Tort Tank and you happen to live in Sofia Bulgaria, you can order it  by dropping me a comment with request 🙂

Enjoy ! 🙂

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Posted in Curious Facts, Entertainment, Everyday Life, Mac OS X, Various | No Comments »

Adding another level of security to your shared Debian Linux webhosting server with SuPHP

Tuesday, April 7th, 2015

suphp_improve-apache-security-protect-against-virus-internal-server-infections-suphp-webserver-logo

There are plenty of security schemes and strategies you can implement if you're a Shared Web Hosting company sysadmin however probably the most vital one is to install on Apache + PHP Webserver SuPHP module.

# apt-cache show suphp-common|grep -i descrip -A 4

Description: Common files for mod suphp Suphp consists of an Apache module (mod_suphp for either Apache 1.3.x or Apache 2.x) and a setuid root binary (suphp) that is called by the Apache module to change the uid of the process executing the PHP interpreter to the owner of the php script.

So what SuPHP actuall  does is to run separate CPanel / Kloxo etc. Users with separate username and groupid permissions coinciding with the user present in /etc/passwd , /etc/shadow files existing users, thus in case if someone hacks some of the many customer sites he would be able to only write files and directories under the user with which the security breach occured.

On servers where SuPHP is not installed, all  systemusers are using the same UserID / GuID to run PHP executable scripts under separate domains Virtualhost which are coinciding with Apache (on Debian / Ubuntu  uid, gid – www-data) or on (CentOS / RHEL / Fedora etc. – user apache) so once one site is defaced  exploited by a worm all or most server websites might end up infected with a Web Virus / Worm which will be trying to exploit even more sites of a type running silently in the background.  This is very common scenarios as currently there are donezs of PHP / CSS / Javasripts / XSS vulnerability exploited on VPS and Shared hosting servers due to failure of a customer to update his own CMS  scripts / Website  (Joomla, Wordpress, Drupal etc.) and the lack of resource to regularly monitor all customer activities / websites.

Therefore installing SuPHP Apache module is essential one to install on new serverslarge hosting providers as it saves the admin a lot of headache from spreading malware across all hosted servers sites ..
Some VPS admins that are security freaks tend to also install SuPHP module together with many chrooted Apache / LiteSpeed / Nginx webservers each of which running in a separate Jailed environment.

Of course using SuPHP besides giving a improved security layer to the webserver has its downsides such as increased load for the server and making Apache PHP scripts being interpretted a little bit slower than with plain Apache + PHP but performance difference while running a site on top of SuPHP is often not so drastic so you can live it up ..

Installing SuPHP on a Debian / Ubuntu servers is a piece of cake, just run the as root superuser, usual:
 

# apt-get install libapache2-mod-suphp


Once installed only thing to make is to turn off default installed Apache PHP module (without SuPHP compiled support and restart Apache webserver):
 

# a2dismod php5 …

# /etc/init.d/apache2 restart
…


To test the SuPHP is properly working on the Apache Webserver go into some of many hosted server websites DocumentRoot

And create new file called test_suphp.php with below content:

# vim test_suphp.php
<?php
system('id');
?>

Then open in browser http://whatever-website/test_suphp.php assuming that system(); function is not disabled for security reasons in php.ini you should get an User ID, GroupID bigger than reserved system IDs on GNU / Linux e.g. ID > UID / GID 99

Its also a good idea to take a look into SuPHP configuration file /etc/suphp/suphp.conf and tailor options according to your liking 

If different hosted client users home directories are into /home directory, set in suphp.conf

;Path all scripts have to be in

docroot=/home/


Also usually it is a good idea to set 

umask=0022 

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Posted in Computer Security, Linux, System Administration, Various, Web and CMS | No Comments »

WordPress Security: Fix WordPress wp-config.php improper permissions to protect your sites from Database password steal / Website deface

Thursday, March 12th, 2015

wordpress-security-Fix-wordpress-wp-config-improper-permissions-to-protect-your-sites-from-Database-pass-steal
Keeping WordPress Site / Blog and related installed plugins up-to-date is essential to prevent an attacker to hack into your Site / Database and deface your site, however if you're a company providing shell access from Cpanel / Plesk / Kloxo Panel to customers often customers are messing up permissions leaving important security credential files such as wp-config.php (which is storing user / pass credentials about connection to MySQL / PostgreSQL to have improper permissions and be world readable e.g. have permissions such as 666 or 777 while in reality the WordPress recommended permissions for wp-config.php is 600. I will skip here to explain in details difference between file permissions on Linux as this is already well described in any Linux book, however I just will recommend for any Share hosting Admin where Wordperss is hosted on Lighttpd / Apache Webserver + Some kind of backend database to be extra cautious.

Hence it is very useful to list all your WordPress sites on server wp-config.php permissions with find like this:

 

find /  -iname 'wp-config.php' -print1;

 

I find it a generally good practice to also automatically set all wp-config.php permissions to 600 (6= Read / Write  permissions only for File Owner  user 0 = No permissions for All groups, 0 = No Permissions for all non-owner users)

If find command output gives you some file permissions such as:
 

ls -al /var/www/wordpress-bak/wp-config.php
-rw-rw-rw- 1 www-data www-data 2654 jul 28  2009 wp-config.php

 

E.g. file permission has 666 permissions (Readable for all users), then it is wise to fix this with:
 

chmod 600 /var/www/wordpress-bak/wp-config.php


It is generally a very good practice to run also a chmod 600 to each and every found wp-config.php file on server:
 

find /  -iname 'wp-config.php' -print1 -exec chmod 600 '{}' \;


Above command will also print each file to whcih permission is set to Read / Write for Owner (this si done with -print1 option).

It is a good practice for shared hosting server to always configure a root cronjob to run above find chmod command at least once daily (whenever server hosts 50 – 100 wordpress+ more sites).
 

crontab -u root -l | { cat; echo “05 03 * * * find /  -iname 'wp-config.php' -print1 -exec chmod 600 '{}' \; } | crontab – 


If you don't have the 600 permissions set for all wp-config.php files this security "backdoor" can be used by any existing non-root user to be read and to break up (crack)  in your database and even when there are Deface bot-nets involved to deface all your hosted server wordpress sites.

One of my servers with wordpress has just recently suffered with this little but very important security hole due to a WordPress site directory backup  with improper permissions which allowed anyone to enter MySQL database, so I guess there are plenty of servers with this hidden vulnerability silently living.

Many thanks to my dear friend (Dimitar Paskalev) Nomen for sharing with me about this vulnerability! Very important note to make here is admins who are using some security enhancement modules such as SuPHP (which makes Apache webserver to run Separate Website instances with different user), should be careful with his set all wp-config.php modules to Owner, as it is possible the wp-config.php owner change to make customer WP based websites inaccessible.

Another good security measure to  protect your server WordPress based sites from malicious theme template injections (for both personal own hosted wordpress based blog / sites or a WordPress hosting company) is to install and activate WordPress Antivirus plugin.

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Posted in Computer Security, Linux, System Administration, Web and CMS, Wordpress | No Comments »

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