Friday, August 29, 2008

Create sub-interfaces in Linux

You can easily create sub interfaces in Linux. As root issue the following commands
linux #ifconfig eth0:1
linux # ifconfig eth0:2
This creates two subinterfaces to the eth0 device.
To make the change peramanent you have to include the settings in /etc/rc.local file in your linux machine. Otherwise these changes are lost when the system is restarted.
In RedHat/Fedora machines you can copy /etc/network-scripts/network/ifcfg-eth0 to /etc/network-scripts/network/ifcfg-eth0:1 and /etc/network-scripts/network/ifcfg-eth0:2 .
This makes changes permanent in RedHat/Fedora. In the debian machines the file to change is /etc/network/interfaces.

Monday, August 11, 2008

Zenmap - nmap frontend for Linux

Zenmap is a very good nmap gui frontend. Debian users have it in their default debian repository. To install from a debian machine give (as root or use sudo )

#aptitude install zenmap

The program was developed as a part of google summer code.

Tuesday, August 05, 2008

Setup network bridge in Debian and RedHat Linux

We can setup a network bridge in Debian and Redhat systems using the following methods

In RedHat Linux do the following

First install bridge-utils using yum or rpm or utility you like

Remove the ip address of the ethernet interfaces. You need a minimum of two

Then issue the following commands

#> brctl addbr br0

#> brctl addif br0 eth0
#> brctl addif br0 eth1
#> ip link set br0 up

And the bridge is ready.

To set ip address to bridge you can use

#> ip addr add brd + dev br0

To configure routing on that bridge use the following command. This sets default gateway

#> route add default gw dev br0.

In Debian use the following commands

To install bridge-utils

aptitude install bridge-utils

Then issue following commands

auto br0
iface br0 inet static
bridge_ports eth0

To make the change permanent you have to enter these commands (except the installing command) in rc.local file in the /etc directory (Redhat ) /etc/network/interfaces ( for Debian based systems).

The brctl comes with various options inlcuding stp and others. Read manpage for details.


>#man brctl