Debian Tutorials » network

Configuring port forwarding with rinetd

aip — Sat, 12 Jun 2010 22:05:16 +0000

inetd redirects TCP connections from one IP address and port to another. rinetd is a single-process server which handles any number of connections to the address/port pairs specified in the file /etc/rinetd.conf. Since rinetd runs as a single process using nonblocking I/O, it is able to redirect a large number of connections without a severe impact on the machine. This makes it practical to run TCP services on machines inside an IP masquerading firewall.

1. Install rinetd

apt-get install rinetd

2. Add some forwarding rules (pico /etc/rinetd.conf)

# bindadress bindport connectaddress connectport 0.0.0.0 80 209.85.229.104 80 # HTTP 0.0.0.0 110 209.85.229.109 110 # POP3 0.0.0.0 143 209.85.229.109 143 # IMAP

These rules will forward all http, pop3 and imap connections to Google's web, pop3 and imap servers. It's just an example but it may make more sense to forward for example port 80 on a public IP address to the internal network to a server that does not have a public IP address.

3. Restart rinetd

/etc/init.d/rinetd restart

Now enter http://youserver in a web browser and you'll see Google search.

Installing ntop network monitoring tool

aip — Sat, 26 Sep 2009 20:27:21 +0000

ntop is a network traffic probe that shows the network usage, similar to what the popular top Unix command does. ntop is based on libpcap and it has been written in a portable way in order to virtually run on every Unix platform and on Win32 as well.

ntop users can use a a web browser (e.g. netscape) to navigate through ntop (that acts as a web server) traffic information and get a dump of the network status. In the latter case, ntop can be seen as a simple RMON-like agent with an embedded web interface.

1. Install required packages

apt-get install ntop

2. Set administrator password

ntop --set-admin-password

3. Configure ntop to use your correct network adapter if it's not eth0 (optional)

dpkg-reconfigure ntop > eth0 (or your network adapter) > ntop

4. Start ntop

/etc/init.d/ntop start

Now you can access ntop web admin on a location similar to this one: http://192.168.1.100:3000. Just make sure you replace the IP address with your server IP address.

Add an additional IP address to your server

aip — Wed, 05 Aug 2009 22:47:22 +0000

1. Open the network configuration file (pico /etc/network/interfaces)

Check the name of your network interface. You should see a line similar to this one: "iface eth0 inet static". In my case the name is eth0.

Add these lines to the end of the file:

auto eth0:1 iface eth0:1 inet static address 192.168.1.3 netmask 255.255.255.0 broadcast 192.168.1.255 network 192.168.1.0

Replace eth0 by your network interface name. If you are adding multiple IP addresses to the same system, you can increase the number after "eth0:".

2. Activate the new virtual network interface

ifup eth0:1