Posts Tagged ‘Configuration’

Putty load as default session another session – Save other Putty session configuration to default howto

Thursday, November 29th, 2018

putty-load-button-screenshot

Recently I had to use PuTTY which I haven't used for years to open a number of SSH Pernanent Tunnels necessery for my daily work as a SAP Consultant.

I've saved them under a certain new profile and saved the set SSH Tunnel configuration not in the default Session but in separate named one, therefore had to press Load button every time after clicking over my Putty shortcut icon. 

That was annoying and took few seconds out of my life every next morning for about a week, so finally I found osme time to google it and it seemed it is pretty easy to have any Putty sessoin loaded you like.

Here is how:

1. Create a new Putty Shortcut

putty-screenshot1

putty-shortcut-screenshot-windows

Click over Putty icon while holding CTRL + SHIFT (Control SHIFT keys simultaneously ) and move the mouse somewhere on the desktop to create the shortcut.
 

2. Right click on Putty Shortcut

putty-target-screenshot-windows1

putty-target-screenshot-windows2

 

"C:\Program Files\PuTTY\putty.exe" -load "your_saved_session" "username@your_server_address" -pw "your_password"


fill out "target" field of shortcut using above code (alter to your own properties).
click Apply button.

If you need to pass a user and password from Shortcut itself (which is a bad practice for security but sometimes useful, for not so important Tunnels – for example a tunnel to an Open Proxy), do it by typing in the target field like so:
 

"C:\Program Files\PuTTY\putty.exe" -load "your_saved_session" "username@your_server_address" -pw "your_password"

 

And Hooray !!! After that when you click on PuTTy shortcut it loads your session automatically using given username and password.

FreeBSD Jumbo Frames network configuration short how to

Wednesday, March 14th, 2012

FreeBSD Jumbo Frames Howto configure FreeBSD

Recently I wrote a post on how to enable Jumbo Frames on GNU / Linux , therefore I thought it will be useful to write how Jumbo Frames network boost can be achieved on FreeBSD too.

I will skip the details of what is Jumbo Frames, as in the previous article I have thoroughfully explained. Just in short to remind you what is Jumbo Frames and why you might need it? – it is a way to increase network MTU transfer frames from the MTU 1500 to MTU of 9000 bytes

It is interesting to mention that according to specifications, the maximum Jumbo Frames MTU possible for assignment are of MTU=16128
Just like on Linux to be able to take advantage of the bigger Jumbo Frames increase in network thoroughput, you need to have a gigabyt NIC card/s on the router / server.

1. Increasing MTU to 9000 to enable Jumbo Frames "manually"

Just like on Linux, the network tool to use is ifconfig. For those who don't know ifconfig on Linux is part of the net-tools package and rewritten from scratch especially for GNU / Linux OS, whether BSD's ifconfig is based on source code taken from 4.2BSD UNIX

As you know, network interface naming on FreeBSD is different, as there is no strict naming like on Linux (eth0, eth1, eth2), rather the interfaces are named after the name of the NIC card vendor for instance (Intel(R) PRO/1000 NIC is em0), RealTek is rl0 etc.

To set Jumbro Frames Maximum Transmission Units of 9000 on FreeBSD host with a Realtek and Intel gigabyt ethernet cards use:freebsd# /sbin/ifconfig em0 192.168.1.2 mtu 9000
freebsd# /sbin/ifconfig rl0 192.168.2.2 mtu 9000

!! Be very cautious here, as if you're connected to the system remotely over ssh you might loose connection to it because of broken routing.

To prevent routing loss problems, if you're executing the above two commands remotely, you better run them in GNU screen session:

freebsd# screen
freebsd# /sbin/ifconfig em0 192.168.1.2 mtu 9000; /sbin/ifconfig rl0 192.168.1.2 mtu 9000; \
/etc/rc.d/netif restart; /etc/rc.d/routed restart

2. Check MTU settings are set to 9000

If everything is fine the commands will return empty output, to check further the MTU is properly set to 9000 issue:

freebsd# /sbin/ifconfig -a|grep -i em0em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 9000freebsd# /sbin/ifconfig -a|grep -i rl0
rl0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 9000

3. Reset routing for default gateway

If you have some kind of routing assigned for em0 and rl0, network interfaces they will be affected by the MTU change and the routing will be gone. To reset the routing to the previously properly assigned routing, you have to restart the BSD init script taking care for assigning routing on system boot time:

freebsd# /etc/rc.d/routing restart
default 192.168.1.1 done
add net default: gateway 192.168.1.1
Additional routing options: IP gateway=YES.

4. Change MTU settings for NIC card with route command

There is also a way to assign higher MTU without "breaking" the working routing, e.g. avoiding network downtime with bsd route command:

freebsd# grep -i defaultrouter /etc/rc.conf
defaultrouter="192.168.1.1"
freebsd# /sbin/route change 192.168.1.1 -mtu 9000
change host 192.168.1.1

5. Finding the new MTU NIC settings on the FreeBSD host

freebsd# /sbin/route -n get 192.168.1.1
route to: 192.168.1.1
destination: 192.168.1.1
interface: em0
flags: <UP,HOST,DONE,LLINFO,WASCLONED>
recvpipe sendpipe ssthresh rtt,msec rttvar hopcount mtu expire
0 0 0 0 0 0 9000 1009

6. Set Jumbo Frames to load automatically on system load

To make the increased MTU to 9000 for Jumbo Frames support permanent on a FreeBSD system the /etc/rc.conf file is used:

The variable for em0 and rl0 NICs are ifconfig_em0 and ifconfig_rl0.
The lines to place in /etc/rc.conf should be similar to:

ifconfig_em0="inet 192.168.1.1 netmask 255.255.255.0 media 1000baseTX mediaopt half-duplex mtu 9000"
ifconfig_em0="inet 192.168.1.1 netmask 255.255.255.0 media 1000baseTX mediaopt half-duplex mtu 9000"

Change in the above lines the gateway address 192.168.1.1 and the netmask 255.255.255.0 to yours corresponding gw and netmask.
Also in the above example you see the half-duplex ifconfig option is set insetad of full-duplex in order to prevent some duplex mismatches. A full-duplex could be used instead, if you're completely sure on the other side of the host is configured to support full-duplex connections. Otherwise if you try to set full-duplex with other side set to half-duplex or auto-duplex a duplex mismatch will occur. If this happens insetad of taking the advantage of the Increase Jumbo Frames MTU the network connection could become slower than originally with standard ethernet MTU of 1500. One other bad side if you end up with duplex-mismatch could be a high number of loss packets and degraded thoroughout …

7. Setting Jumbo Frames for interfaces assigning dynamic IP via DHCP

If you need to assign an MTU of 9000 for a gigabyt network interfaces, which are receiving its TCP/IP network configuration over DHCP server.
First, tell em0 and rl0 network interfaces to dynamically assign IP addresses via DHCP proto by adding in /etc/rc.conf:

ifconfig_em0="DHCP"
ifconfig_rl0="DHCP"

Secondly make two files /etc/start_if.em0 and /etc/start_if.rl0 and include in each file:

ifconfig em0 media 1000baseTX mediaopt full-duplex mtu 9000
ifconfig rl0 media 1000baseTX mediaopt full-duplex mtu 9000

Copy / paste in root console:

echo 'ifconfig em0 media 1000baseTX mediaopt full-duplex mtu 9000' >> /etc/start_if.em0
echo 'ifconfig rl0 media 1000baseTX mediaopt full-duplex mtu 9000' >> /etc/start_if.rl0

Finally, to load the new MTU for both interfaces, reload the IPs with the increased MTUs:

freebsd# /etc/rc.d/routing restart
default 192.168.1.1 done
add net default: gateway 192.168.1.1

8. Testing if Jumbo Frames is working correctly

To test if an MTU packs are transferred correctly through the network you can use ping or tcpdumpa.) Testing Jumbo Frames enabled packet transfers with tcpdump

freebsd# tcpdump -vvn | grep -i 'length 9000'

You should get output like:

16:40:07.432370 IP (tos 0x0, ttl 50, id 63903, offset 0, flags [DF], proto TCP (6), length 9000) 192.168.1.2.80 > 192.168.1.1.60213: . 85825:87285(1460) ack 668 win 14343
16:40:07.432588 IP (tos 0x0, ttl 50, id 63904, offset 0, flags [DF], proto TCP (6), length 9000) 192.168.1.2.80 > 192.168.1.1.60213: . 87285:88745(1460) ack 668 win 14343
16:40:07.433091 IP (tos 0x0, ttl 50, id 63905, offset 0, flags [DF], proto TCP (6), length 9000) 192.168.1.2.80 > 192.168.1.1.60213: . 23153:24613(1460) ack 668 win 14343
16:40:07.568388 IP (tos 0x0, ttl 50, id 63907, offset 0, flags [DF], proto TCP (6), length 9000) 192.168.1.2.80 > 192.168.1.1.60213: . 88745:90205(1460) ack 668 win 14343
16:40:07.568636 IP (tos 0x0, ttl 50, id 63908, offset 0, flags [DF], proto TCP (6), length 9000) 192.168.1.2.80 > 192.168.1.1.60213: . 90205:91665(1460) ack 668 win 14343
16:40:07.569012 IP (tos 0x0, ttl 50, id 63909, offset 0, flags [DF], proto TCP (6), length 9000) 192.168.1.2.80 > 192.168.1.1.60213: . 91665:93125(1460) ack 668 win 14343
16:40:07.569888 IP (tos 0x0, ttl 50, id 63910, offset 0, flags [DF], proto TCP (6), length 9000) 192.168.1.2.80 > 192.168.1.1.60213: . 93125:94585(1460) ack 668 win 14343

b.) Testing if Jumbo Frames are enabled with ping

Testing Jumbo Frames with ping command on Linux

linux:~# ping 192.168.1.1 -M do -s 8972
PING 192.168.1.1 (192.168.1.1) 8972(9000) bytes of data.
9000 bytes from 192.168.1.1: icmp_req=1 ttl=52 time=43.7 ms
9000 bytes from 192.168.1.1: icmp_req=2 ttl=52 time=43.3 ms
9000 bytes from 192.168.1.1: icmp_req=3 ttl=52 time=43.5 ms
9000 bytes from 192.168.1.1: icmp_req=4 ttl=52 time=44.6 ms
--- 192.168.0.1 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3003ms
rtt min/avg/max/mdev = 2.397/2.841/4.066/0.708 ms

If you get insetad an an output like:

From 192.168.1.2 icmp_seq=1 Frag needed and DF set (mtu = 1500)
From 192.168.1.2 icmp_seq=1 Frag needed and DF set (mtu = 1500)
From 192.168.1.2 icmp_seq=1 Frag needed and DF set (mtu = 1500)
From 192.168.1.2 icmp_seq=1 Frag needed and DF set (mtu = 1500)

--- 192.168.1.1 ping statistics ---
0 packets transmitted, 0 received, +4 errors

This means a packets with maximum MTU of 1500 could be transmitted and hence something is not okay with the Jumbo Frames config.
Another helpful command in debugging MTU and showing which host in a hop queue support jumbo frames is Linux's traceroute

To debug a path between host and target, you can use:

linux:~# traceroute --mtu www.google.com
...

If you want to test the Jumbo Frames configuration from a Windows host use ms-windows ping command like so:

C:\>ping 192.168.1.2 -f -l 8972
Pinging 192.168.1.2 with 8972 bytes of data:
Reply from 192.168.1.2: bytes=8972 time=2ms TTL=255
Reply from 192.168.1.2: bytes=8972 time=2ms TTL=255
Reply from 192.168.1.2: bytes=8972 time=2ms TTL=255
Reply from 192.168.1.2: bytes=8972 time=2ms TTL=255
Ping statistics for 192.168.1.2:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 2ms, Maximum = 2ms, Average = 2ms

Here -l 8972 value is actually equal to 9000. 8972 = 9000 – 20 (20 byte IP header) – 8 (ICMP header)

How to configure networking in CentOS, Fedora and other Redhat based distros

Wednesday, June 1st, 2011

On Debian Linux I’m used to configure the networking via /etc/network/interfaces , however on Redhat based distributions to do a manual configuration of network interfaces is a bit different.

In order to configure networking in CentOS there is a special file for each interface and some values one needs to fill in to enable networking.

These network adapters configuration files for Redhat based distributions are located in the files:

/etc/sysconfig/network-scripts/ifcfg-*

Just to give you and idea on the content of this network configuration file, here is how it looks like:

[root@centos:~ ]# cat /etc/sysconfig/network-scripts/ifcfg-eth0
# Broadcom Corporation NetLink BCM57780 Gigabit Ethernet PCIe
DEVICE=eth0
BOOTPROTO=static
DHCPCLASS=
HWADDR=00:19:99:9C:08:3A
IPADDR=192.168.0.1
NETMASK=255.255.252.0
ONBOOT=yes

This configuration is of course just for eth0 for other network card names and devices, one needs to look up for the proper file name which corresponds to the network interface visible with the ifconfig command.
For instance to list all network interfaces via ifconfig use:

[root@centos:~ ]# /sbin/ifconfig |grep -i 'Link encap'|awk '{ print $1 }'
eth0
eth1
lo

In this case there are only two network cards on my host.
The configuration files for the ethernet network devices eth0 and eth1 from below example are located in files /etc/sysconfig/network-scripts/ifcfg-eth{1,2}

/etc/sysconfig/network-scripts/ directory contains plenty of shell scripts related to Fedora networking.
This directory contains actually the networking boot time load up rules for fedora and CentOS hosts.

The complete list of options available which can be used in /etc/sysconfig/network-scripts/ifcfg-ethx is located in:
/usr/share/doc/initscripts-*/sysconfig.txt

, to quickly observe the documentation:

[root@centos:~ ]# less /usr/share/doc/initscripts-*/sysconfig.txt

One typical example of configuring a CentOS based host to possess a static IP address (192.168.1.5) and a gateway (192.168.1.1), which will be assigned in boot time during the /etc/init.d/network is loaded is:

[root@centos:~ ]# cat /etc/sysconfig/network-scripts/ifcfg-eth0
# Broadcom Corporation NetLink BCM57780 Gigabit Ethernet PCIe
IPV6INIT=no
BOOTPROTO=static
ONBOOT=yes
USERCTL=yes
TYPE=Ethernet
DEVICE=eth0
IPADDR=192.168.1.5
NETWORK=192.168.1.0
GATEWAY=192.168.1.1
BROADCAST=192.168.1.255
NETMASK=255.255.255.0

After some changes to the network configuration files are made, to load up the new rules a /etc/init.d/network script restart is necessery with the command:

[root@centos:~ ]# /etc/init.d/network restart

Of course one can always use /etc/rc.local script as universal way to configure network rules on a Redhat based host, however using methods like rc.local to load up, ifconfig or route rules in a Fedora would break the distribution logic and therefore is not recommended.

There is also a serious additional reason against using /etc/rc.local post init commands load up script.
If one uses rc.local to load up and configure the networing, the network will get initialized only after all the other scripts in /etc/init.d/ gets started.

Therefore using /etc/rc.local might also be DANGEROUS!, if used remotely via (ssh), supposedly it might completely fail to load the networking, if all bringing the server interfaces relies on it.

Here is an example, imagine that some of the script set in to load up during a CentOS boot up hangs and does continue to load forever (for example after some crucial software upate), as a consequence the /etc/rc.local script will never get executed as it only starts up after all the rest init scripts had succesfully completed execution.

A network eth1 interface configuration for a Fedora host which has to fetch it’s network settings automatically via DHCP is as follows:

[root@fedora:/etc/network:]# cat /etc/sysconfig/network-scripts/ifcfg-eth1
# Intel Corporation 82557/8/9 [Ethernet Pro 100]DEVICE=eth1
BOOTPROTO=dhcp
HWADDR=00:0A:E4:C9:7B:51
ONBOOT=yes

To sum it up I think Fedora’s /etc/sysconfig/network-scripts methodology to configure ethernet devices is a way inferior if compared to Debian.

In GNU/Debian Linux configuration of all networking is (simpler)!, everything related to networking is in one single file ( /etc/network/interfaces ), moreover getting all the thorough documentation for the network configurations options for the interfaces is available as a system wide manual (e.g. man interfaces).

Partially Debian interfaces configuration is a bit more complicated in terms of syntax if matched against Redhat’s network-scripts/ifcfg-*, lest that generally I still find Debian’s manual network configuration interface to be easier to configure networking manually vicommand line.

How to substitute default TinyMCE Joomla Content editor with JCE Content Editor

Tuesday, May 31st, 2011

This content editor is really awesome compared to the default editor TinyMCE. If you want to have an options rich content editor for Joomla, then this is the one for you 🙂
download JCE Content Editor here

After installing the JCE Joomla content editor in order to enable it as a default editor you need to go to the following location:

Site -> Global Configuration -> Default WYSIWYG Editor

There place on Editor TinyMCE and change it with Editor – JCE

Now go to edit some article, and you will see the difference in the editor 🙂

7. Add gallery Joomla capabilities with sigplus (Image Gallery Plus) and Very Simple Image Gallery

sigplus Image Gallery Plus is a straightforward way to add image or photo galleries to a Joomla article with a simple syntax. It takes a matter of minutes to set up a gallery but those who are looking for a powerful gallery solution will not be disappointed either: sigplus is suitable for both beginner and advanced users.
 

A few helpful Bind DNS server configuration options

Wednesday, March 17th, 2010

It’s quite useful in bind to have the following configurations options in either named.conf options {} configuration block or (in case if on Debian Linux in named.conf.options.
Please edit your required file respectively and find the options {} directive and set within the options {} block the following:


zone-statistics yes;
notify yes;
transfer-format many-answers;

Here I have to clarify that the zone-statistics directive instructs the server to collect statistical data about all zone files, this statistics can later be accessed via the:
rndc stats command.

transfer-format many-answers is actually a default directive since bind 9 and you might even like to skip that one if on bind version 9 or 9+
notify yes; – will instruct the nameserver to replicate change in zone files to a seconday configured name server.

Another really vital thing in my view is to enable Bind DNS server logging into file.

In order to do that put in named.conf:

logging {
channel _default_log {
file "/var/log/named/named.log";
severity debug;
print-time yes;
};
category default {
_default_log;
};

Note that it’s required to create the log file with proper permissions as in the location where specified in the above configuration in this case /var/log/named/named.log :


debian-server# mkdir -p /var/log/named
debian-server# touch /var/log/named/named.log
debian-server# chown -R bind:bind /var/log/named/

In this case I change the directory and file to be owned by the bind user and group, however on different linux distribution like Redhat the user could be different like on Redhat the user is usually named.
To find the correct user permissions check the user with which the Bind server is running using a simple:

debian-server# ps axu|grep -i bind
or
# ps axu|grep -i named