How do I enable IP masquerading and forwarding?

How do I enable IP masquerading and forwarding?


Author: Joel Morgan
Email: jpmorgan@mindspring.com

System Architecture: Intel
RedHat Release: RHL 5.1 (Manhattan)
FAQ Category: Networking and netcfg
Modification Date: Jan 18, 1999

Question:

How do I enable IP masquerading and forwarding?

Answer:

RH 5.1 and RH 5.2 support Ip-masquerading without recompiling the kernel.

Enable IP forwarding by changing /etc/sysconfig/network as follows:
FORWARD_IPV4=yes

Edit /etc/rc.d/rc.local to enable IP Masquerading
/sbin/ipfwadm -F -p deny 
/sbin/ipfwadm -F -a m -S 192.168.1.0/24 -D 0.0.0.0/0

Of course this asumes you network IP is 192.168.1.0.

You can also add the following lines to act as proxies for particular
services. Without these, they won't work.

/sbin/depmod -a 
/sbin/modprobe ip_masq_ftp.o 
/sbin/modprobe ip_masq_irc.o 
/sbin/modprobe ip_masq_quake.o 
/sbin/modprobe ip_masq_raudio.o 
/sbin/modprobe ip_masq_vdolive.o 

Suggested reading: 
man ipfwadm

References:

None specified.