Port forwarding

[seanf77]

If I am using IPCHAINS on my firewall, how would I go about forwarding external FTP requests on ports 20/21 to my internal FTP server sitting at 192.168.0.3?

Thanks!
Sean

 

[IPconfig]

what you would need is a package called ipmasqadm

i currently forward traffic to port 3306 (mysql) to an internal box from my proxy which has a public ip
after installing the package what you do is make sure you have the modules loaded i.e ip_masq_portfw you will prolly have to modrpobe it.
since you want to forwad traffic to port 21 the syntax in your firewall would be

#Allow ftp
$IPCHAINS -A input -p tcp -s your_public_ip -d $OUTERNET 21 -j ACCEPT

#Masq ftp connections
$IPCHAINS -A forward -p tcp -s 192.168.0.3 21 -j MASQ
/usr/sbin/ipmasqadm portfw -a -P tcp -L your_public_IP 21
-R 192.168.0.3 21

after setting these rules restart your firewall offcourse and then to make sure your rules have registered you can check by issuing this command

ipmasqadm portfw -l

and that is about it ...for refference check this site out

http://www.usenix.org/publications/login/1999-11/features/linux.html

IPconfig

 

[plook]

Hi there...

Is it possible that ipmasqadm is not compatible with Kernel 2.4 ? I tried to install the package but RPM gave me an error message saying "Kernel>=2.3.0 conflicts with ipmasqadm-0.4.3.i686.rpm"

Is there a way to install this package anyway ? Or another way to do this kind of port forwarding ?

Thanks

 

[ifincham]

Hi,







If you can't get ipmasqadm to work, the best thing would be to drop ipchains for the newer iptables which



(effective 2.4 series kernels) provides fuller nat & masquerading functionality anyway. See -->

http://netfilter.samba.org/documentation/HOWTO/NAT-HOWTO-6.html#ss6.2

Regards