Posts Tagged ‘network traffic’

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 !

Text Monitoring of connection server (traffic RX / TX) business in ASCII graphs with speedometer / Easy Monitor network traffic performance

Friday, May 4th, 2012

While reading some posts online related to MS-Windows TcpViewnetwork traffic analyzing tool. I've came across very nice tool for tracking connection speed for Linux (Speedometer). If I have to compare it, speedometer is somehow similar to nethogs and iftop bandwidth network measuring utilities .

What differentiates speedometer from iftop / nethogs / iptraf is it is more suitable for visualizing a network file or data transfers.
The graphs speedometer draws are way easier to understand, than iftop graphs.

Even complete newbies can understand it with no need for extraordinary knowledge in networking. This makes Speedometer, a top tool to visually see the amount of traffic flowing through server network interface (eth0) … (eth1) etc.

What speedometer shows is similar to the Midnight Commander's (mc) file transfer status bar, except the statistics are not only for a certain file transfer but can show overall statistics over server passing network traffic amount (though according to its manual it can be used to also track individual file transfers).

The simplicity for basic use makes speedometer nice tool to track for network congestion issues on Linux. Therefore it is a  must have outfit for every server admin. Below you see a screenshot of my terminal running speedometer on a remote server.

Speedometer ascii traffic track server network business screenshot in byobu screen like virtual terminal emulator

1. Installing speedometer on Debian / Ubuntu and Debian derivatives

For Debian and Ubuntu server administrators speedometer is already packaged as a deb so its installation is as simple as:

debian:~# apt-get --yes install speedometer
....

2. Installing speedometer from source for other Linux distributions CentOS, Fedora, SuSE etc.

Speedometer is written in python programming language, so in order to install and use on other OS Linux platforms, it is necessery to have installed (preferably) an up2date python programming language interpreter (python ver. 2.6 or higher)..
Besides that it is necessary to have installed the urwid -( console user interface library for Python) available for download via excess.org/urwid/

 

Hence to install speedometer on RedHat based Linux distributions one has to follow these steps:

a) Download & Install python urwid library

[root@centos ~]# cd /usr/local/src
[root@centos src]# wget -q http://excess.org/urwid/urwid-1.0.1.tar.gz
[root@centos src]# tar -zxvvf urwid-1.0.1.tar.gz
....
[root@centos src]# cd urwid-1.0.1
[root@centos urwid-1.0.1]# python setup.py install
running install
running build
running build_py
creating build
creating build/lib.linux-i686-2.4
creating build/lib.linux-i686-2.4/urwid
copying urwid/tests.py -> build/lib.linux-i686-2.4/urwid
copying urwid/command_map.py -> build/lib.linux-i686-2.4/urwid
copying urwid/graphics.py -> build/lib.linux-i686-2.4/urwid
copying urwid/vterm_test.py -> build/lib.linux-i686-2.4/urwid
copying urwid/curses_display.py -> build/lib.linux-i686-2.4/urwid
copying urwid/display_common.py -> build/lib.linux-i686-2.4/urwid
....

b) Download and install python-setuptools

python-setuptools is one other requirement of speedometer, happily on CentOS and Fedora the rpm package is already there and installable with yum:

[root@centos ~]# yum -y install python-setuptools
....

c) Download and install Speedometer

[root@centos urwid-1.0.1]# cd /usr/local/src/
[root@centos src]# wget -q http://excess.org/speedometer/speedometer-2.8.tar.gz
[root@centos src]# tar -zxvvf speedometer-2.8.tar.gz
.....
[root@centos src]# cd speedometer-2.8
[root@centos speedometer-2.8]# python setup.py install
Traceback (most recent call last):
File "setup.py", line 26, in ?
import speedometer
File "/usr/local/src/speedometer-2.8/speedometer.py", line 112
n = n * granularity + (granularity if r else 0)
^

While running the CentOS 5.6 installation of speedometer-2.8, I hit the
"n = n * granularity + (granularity if r else 0)
error.

After consultation with some people in #python (irc.freenode.net), I've figured out this error is caused due the outdated version of python interpreter installed by default on CentOS Linux 5.6. On CentOS 5.6 the python version is:

[root@centos ~]# python -V
Python 2.4.3

As I priorly said speedometer 2.8's minimum requirement for a python to be at v. 2.6. Happily there is quick way to update python 2.4 to python 2.6 on CentOS 5.6, as there is an RPM repository maintained by Chris Lea which contains RPM binary of python 2.6.

To update python 2.4 to python 2.6:

[root@centos speedometer-2.8]# rpm -Uvh http://yum.chrislea.com/centos/5/i386/chl-release-5-3.noarch.rpm[root@centos speedometer-2.8]# rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-CHL[root@centos speedometer-2.8]# yum install python26

Now the newly installed python 2.6 is executable under the binary name python26, hence to install speedometer:

[root@centos speedometer-2.8]# python26 setup.py install
[root@centos speedometer-2.8]# chown root:root /usr/local/bin/speedometer
[root@centos speedometer-2.8]# chmod +x /usr/local/bin/speedometer

[root@centos speedometer-2.8]# python26 speedometer -i 1 -tx eth0

The -i will instruct speedometer to refresh the screen graphs once a second.

3. Using speedometer to keep an eye on send / received traffic network congestion

To observe, the amount of only sent traffic via a network interface eth0 with speedometer use:

debian:~# speedometer -tx eth0

To only keep an eye on received traffic through eth0 use:

debian:~# speedometer -rx eth0

To watch over both TX and RX (Transmitted and Received) network traffic:

debian:~# speedometer -tx eth0 -rx eth0

If you want to watch in separate windows TX and RX traffic while  running speedometer you can run in separate xterm windows speedometer -tx eth0 and speedometer -rx eth0, like in below screenshot:

Monitor Received and Transmitted server Network traffic in two separate xterm windows with speedometer ascii graphs

4. Using speedometer to test network maximum possible transfer speed between server (host A) and server (host B)

The speedometer manual suggests few examples one of which is:

How fast is this LAN?

host-a$ cat /dev/zero | nc -l -p 12345
host-b$ nc host-a 12345 > /dev/null
host-b$ speedometer -rx eth0

When I red this example in speedometer's manual, it wasn't completely clear to me what the author really meant, but a bit after when I thought over the example I got his point.

The idea behind this example is that a constant stream of zeros taken from /dev/zero will be streamed over via a pipe (|) to nc which will bind a port number 12345, anyone connecting from another host machine, lets say a server with host host-b to port 12345 on machine host-a will start receiving the /dev/zero streamed content.

Then to finally measure the streamed traffic between host-a and host-b machines a speedometer is started to visualize the received traffic on network interface eth0, thus measuring the amount of traffic flowing from host-a to host-b

I give a try to the exmpls, using for 2 test nodes my home Desktop PC, Linux running  arcane version of Ubuntu and my Debian Linux notebook.

First on the Ubuntu PC I issued
 

hipo@hip0-desktop:~$ cat /dev/zero | nc -l -p 12345
 

Note that I have previously had installed the netcat, as nc is not installed by default on Ubuntu and Debian. If you, don't have nc installed yet, install it with:

apt-get –yes install netcat

"cat /dev/zero | nc -l -p 12345" will not produce any output, but will display just a blank line.

Then on my notebook I ran the second command example, given in the speedometer manual:
 

hipo@noah:~$ nc 192.168.0.2 12345 > /dev/null

Here the 192.168.0.2 is actually the local network IP address of my Desktop PC. My Desktop PC is connected via a normal 100Mbit switch to my routing machine and receives its internet via  NAT. The second test machine (my laptop), gets its internet through a WI-FI connection received by a Wireless Router connected via a UTP cable to the same switch to which my Desktop PC is connected.

Finally to test / get my network maximum thoroughput I had to use:

hipo@noah:~$ speedometer -rx wlan0

Here, I  monitor my wlan0 interface, as this is my (laptop) wireless card interface over which I have connectivity to my local network and via which through the the WI-FI router I get connected to the internet.

Below is a snapshot captured showing approximately what is the max network thoroughput from:

Desktop PC -> to my Thinkpad R61 laptop

Using Speedometer to test network thorougput between two network server hosts screenshot Debian Squeeze Linux

As you can see in the shot approximately the maximum network thoroughput is in between:
2.55MB/s min and 2.59MB/S max, the speed is quite low for a 100 MBit local network, but this is normal as most laptop wireless adapters hardly transfer traffic in more than 10 to 20 MBits per sec.

If the same nework thoroughput test is conducted between two machines both connected to a same 100 M/bit switch, the traffic should be at least a 8 MB/sec.

There is something, else to take in consideration that probably makes the provided example network thoroughput measuring a bit inaccurate. The fact that the /dev/zero content is stremed over is slowing down the zeroes sent over network because of the  pipe ( | ) use slows down the stream.

5. Using speedometer to visualize maximum writting speed to a local hard drive on Linux

In the speedometer manual, I've noticed another interesting application of this nifty tool.

speedometer can be used to track and visualize the maximum writing speed a hard disk drive or hard drive partition can support on Linux OS:

A copy paster from the manual text is as follows:

How fast can I write data to my filesystem? (with at least 1GB free)
dd bs=1000000 count=1000 if=/dev/zero of=bigfile &
speedometer bigfile

However, when I tried copy/pasting the example in terminal, to test the maximum writing speed to an external USB hard drive, only dd command was started and speedometer failed to initialize and display graphs of the file creation speed.

I've found a little "hack" that makes the man example work by adding a 3 secs sleep like so:

debian:/media/Expansion Drive# dd bs=1000000 count=1000 if=/dev/zero of=bigfile & sleep 3; speedometer bigfile

Here is a screenshot of the bigfile created by dd and tracked "in real time" by speedometer:

How fast is writting data to local USB expandable hard disk Debian Linux speedometer screenshot

Actually the returned results from this external USB drive are, quite high, the possible reason for that is it is connected to my laptop over an USB protocol verion 3.

6. Using Speedometer to keep an eye on file download in progress

This application of speedometer is mostly useless especially on Linux where it is used as a Desktop.

However in some occasions if files are transferred over ssh or in non interactive FTP / Samba file transfers between Linux servers it can come handy.

To visualize the download and writing speed of lets say FTP transferred .AVI movie (during the actual file transfer) on the download host issue:

# speedometer Download-Folder/What-goes-around-comes-around.avi

7. Estimating approximate time for file transfer

There is another section in the speedometer manual pointing of the program use to calculate the time remaining for a file transfer.

The (man speedometer) provided example text is:

How long it will take for my 38MB transfer to finish?
speedometer favorite_episode.rm $((38*1024*1024))

At first glimpse it hard to understand (like the other manual example). A bit of reasoning and I comprehend what the man author meant by the obscure calculation:

$((38*1024*1024))

This is a formula used in which 38 has to be substituted with the exact file size amount of the transferred file. The author manual used a 38MB file so this is why he put $((38* … in the formula.

I give it a try – (just for the sake to see how it works) with a file with a size of 2500MB, in below two screenshot pictures I show my preparation to copy the file and the actual copying / "real time" transfer tracking with speedometer's status percentage completion bar.

xterm terminal copy file and estimate file copying operation speed on linux with speedometer preparation

Two xterm terminals one is copying a file the other one uses speedometer to estimate the time remaining to complete the file transfer from expansion USB hard drive to my laptop harddrive

 

How to find out all programs bandwidth use with (nethogs) top like utility on Linux

Friday, September 30th, 2011

Just run across across a super nice top like, program for system administrators, its called nethogs and is definitely entering my “l337” admin outfit next to tools like iftop, nettop, ettercap, darkstat htop, iotop etc.

nethogs is ultra easy to use, to get immediately in console statistics about running processes UPLOAD and DOWNLOAD bandwidth consumption just run it:

linux:~# nethogs

Nethogs screenshot on Linux Server with Nginx
Nethogs running on Debian GNU/Linux serving static web content with Nginx

If you need to check what program is using what amount of network bandwidth, you will definitely love this tool. Having information of bandwidth consumption is also viewable partially with iftop, however iftop is unable to track the bandwidth consumption to each process using the network thus it seems nethogs is unique at what it does.

Nethogs supports IPv4 and IPv6 as well as supports network traffic over ppp. The tool is available via package repositories for Debian GNU/Lenny 5 and Debian Squeeze 6.

To install Nethogs on CentOS and Fedora distributions, you will have to install it from source. On CentOS 5.7, latest nethogs which as of time of writting this article is 0.8.0 compiles and installs fine with make && make install commands.

In the manner of thoughts of network bandwidth monitoring, another very handy tool to add extra understanding on what kind of traffic is crossing over a Linux server is jnettop
jnettop shows which hosts/ports is taking up the most network traffic.
It is available for install via apt in Debian 5/6).

Here is a screenshot on jnettop in action:

Jnettop check network traffic in console

To install jnettop on latest Fedoras / CentOS / Slackware Linux it has to be download and compiled from source via jnettop’s official wiki page
I’ve tested jnettop install from source on CentOS release 5.7 and it seems to compile just fine using the usual compile commands:

[root@prizebg jnettop-0.13.0]# ./configure
...
[root@prizebg jnettop-0.13.0]# make
...
[root@prizebg jnettop-0.13.0]# make install

If you need to have an idea on the network traffic passing by your Linux server distringuished by tcp/udp/icmp network protocols and services like ssh / ftp / apache, then you will definitely want to take a look at nettop (if of course not familiar with it yet).
Nettop is not provided as a deb package in Debian and Ubuntu, where it is included as rpm for CentOS and presumably Fedora?
Here is a screenshot on nettop network utility in action:

Nettop server traffic division by protocol screenshot
FreeBSD users should be happy to find out that jnettop and nettop are part of the ports tree and the two can be installed straight, however nethogs would not work on FreeBSD, I searched for a utility capable of what Nethogs can, but couldn’t find such.
It seems the only way on FreeBSD to track bandwidth back and from originating process is using a combination of iftop and sockstat utilities. Probably there are other tools which people use to track network traffic to the processes running on a hos and do general network monitoringt, if anyone knows some good tools, please share with me.

How to find and kill Abusers on OpenVZ Linux hosted Virtual Machines (Few bash scripts to protect OpenVZ CentOS server from script kiddies and easify the daily admin job)

Friday, July 22nd, 2011

OpenVZ Logo - Anti Denial Of Service shell scripts

These days, I’m managing a number of OpenVZ Virtual Machine host servers. Therefore constantly I’m facing a lot of problems with users who run shit scripts inside their Linux Virtual Machines.

Commonly user Virtual Servers are used as a launchpad to attack hosts do illegal hacking activities or simply DDoS a host..
The virtual machines users (which by the way run on top of the CentOS OpenVZ Linux) are used to launch a Denial service scripts like kaiten.pl, trinoo, shaft, tfn etc.

As a consequence of their malicious activities, oftenly the Data Centers which colocates the servers are either null routing our server IPs until we suspend the Abusive users, or the servers go simply down because of a server overload or a kernel bug hit as a result of the heavy TCP/IP network traffic or CPU/mem overhead.

Therefore to mitigate this abusive attacks, I’ve written few bash shell scripts which, saves us a lot of manual check ups and prevents in most cases abusers to run the common DoS and “hacking” script shits which are now in the wild.

The first script I’ve written is kill_abusers.sh , what the script does is to automatically look up for a number of listed processes and kills them while logging in /var/log/abusers.log about the abusive VM user procs names killed.

I’ve set this script to run 4 times an hour and it currently saves us a lot of nerves and useless ticket communication with Data Centers (DCs), not to mention that reboot requests (about hanged up servers) has reduced significantly.
Therefore though the scripts simplicity it in general makes the servers run a way more stable than before.

Here is OpenVZ kill/suspend Abusers procs script kill_abusers.sh ready for download

Another script which later on, I’ve written is doing something similar and still different, it does scan the server hard disk using locate and find commands and tries to identify users which has script kiddies programs in their Virtual machines and therefore are most probably crackers.
The scripts looks up for abusive network scanners, DoS scripts, metasploit framework, ircds etc.

After it registers through scanning the server hdd, it lists only files which are preliminary set in the script to be dangerous, and therefore there execution inside the user VM should not be.

search_for_abusers.sh then logs in a files it’s activity as well as the OpenVZ virtual machines user IDs who owns hack related files. Right after it uses nail mailing command to send email to a specified admin email and reports the possible abusers whose VM accounts might need to either be deleted or suspended.

search_for_abusers can be download here

Honestly I truly liked my search_for_abusers.sh script as it became quite nice and I coded it quite quickly.
I’m intending now to put the Search for abusers script on a cronjob on the servers to check periodically and report the IDs of OpenVZ VM Users which are trying illegal activities on the servers.

I guess now our beloved Virtual Machine user script kiddies are in a real trouble ;P
 

How to install and configure torbutton on Debian / Anonymizing Iceweasel, Firefox on Debian GNU/Linux

Thursday, August 5th, 2010

Tor Onion Logo

There is a quite a buzz online recently about the implications breach of personal privacy by simple browing online.
A week ago I've blogged On How to improve your web browser security for better personal identity
Though there is probably a plenty of more things to be done on guaranteeing your anonymous identity online, the article lacked to mention one very one vital project related with anonymity – the tor Anonymity online project
The project offer the user the right to be anonymous online through a complex constantly expanding network of volunteers which voluntary install and grant access to the installed tor server to be used as a proxy from their computers.
A very thorough explanation on what is tor can be red here
Enabling tor on your personal computer would at least guarantee you that every now and then your traffic browser network traffic (request) would flow through a random tor servers located on a different worldly geographic locations.
Usually the traffic to a destination host would pass through 5 tor network nodes. Where the traffic is unecrypted between last node and the 4th node, while in the other four ones it's completely crypted.
This makes your tracking almost impossible if it's based on technologies like for instance Maxmind's Geoip or Geonames's geographical data base because every now and then you'll appear to be coming to the end point referrar web server originating from a different tor node ip address

The tor server is a free software licensed under the GPL and this is also a good assurance because everybody is able to have a look on the code and this is a further guarantee that the software doesn't include a malicious ways for a middle users to sniff on your traffic.

The tor project has even built a pre-bundled browser ready to be worn by yourself on a usb stick, so you can quickly start using the tor anonymous network on any random computer anywhere.
The tor browser page is available here also Tor Browser Bundle for Windows is available here
Tor server is available for both Windows, Mac OS X, Linux and Linux/BSD Unix
Of course tor is not perfect it opens some other possible doors for attackers which are much less likely to occur if you don't use it, however in general it's better off with tor than without it.

One serious reason for not reason for not using Tor might be that it's usually many times slower than normal browser since, it routes traffic through a different tor network nodes.
So if you decide to go on and use it you better be patient and calm 🙂

Since I'm a Debian user and I really do value my privacy I decided to start using Tor.
In order to start using Tor it's usually necessary to configure your browser to use The TorButoon Firefox browserextension

Nevertheless on Debian GNU/Linux if you try to go the straigh way as explained on Tor's website install the TorButton and configure it to work in cooperation with the polipo caching proxy
You will be not able to browse after enabling straight the tor plugin.
If you try the up-mentioned approach you're probably about to come to errors like:
"the proxy server is refusing connections"
,
Proxy error: 502 Disconnected operation and object not in cache
or
504 Connect to superquizgames.com:80 failed: SOCKS error: host unreachableThe following error occurred while trying to access http://yourwebsite.com/:504 Connect to superquizgames.com:80 failed: SOCKS error: host unreachable

In order to properly install configure and enable the TorButton on my Debian GNU/Linux I had to get through the following steps:

1. Install the polipo caching proxy

debian:~# apt-get install polipo

2. Download and overwrite default polipo configuration with the one from torproject.org

This is necessary to configure in order to have polipo adapted to work with tor, so issue the following commands:

debian:~# cd /etc/polipo
debian:~# wget https://svn.torproject.org/svn/torbrowser/trunk/build-scripts/config/polipo.conf
debian:~# mv config config.bak
debian:~# mv polipo.conf config

3. Restart polipo for the new config settings to take affect

debian:~# /etc/init.d/polipo restart

4. Install the iceweasel-torbutton browser extension

debian:~# apt-get install iceweasel-torbutton

The iceweasel-torbutton will also install you the tor package which is evidently required for the torbutton to operate.
Now you should be ready to go, you can enable the tor use from the tor button which should appear in your browser in the bottom right corner of your browser.
It should look something similar to:

Tor Button screenshot in Iceweasel

Tor Enable/Disable Iceweasel browser Button

To test your Tor Configuration you can use the Test Settings button which is straight available from TorButton's preferences

From here after it might be a good idea to play with the TorButton security settings and configure it according to your liking, bear in mind that you should have a solid knowledge on how browsers work and some basic Internet protocols before you start tampering this options.
If tou don't know what you do you better stop and don't tamper with the torbutton security options.
The only one that you will most probably want to untick is The Disable plugins during Tor usage , stopping this option will allow you to have a flash video streaming display properly, otherwise you won't be able to use , Vbox etc.
Below you see a screenshot of the TorButton Security Settings dialog.

TorButton properties Dialog

To open up this dialog you need to navigate to the TorButto and choose preferences with the right mouse buttons 🙂
Hope this article is informative to somebody out there.
User feedback is mostly welcome! Cheers 🙂