Redirect packages directed to port 5000 to another port
- by tdc
I'm trying to use eboard to connect to the FICS servers (http://www.freechess.org), but it fails because port 5000 is blocked (company firewall). However, I can connect to the server through the telnet port (23):
telnet freechess.org 23
(succeeds)
telnet freechess.org 5000
(fails)
Unfortunately the port number is hardcoded (see here: http://ubuntuforums.org/archive/index.php/t-1613075.html). I'd rather not have to hack the source code as the author of that thread ended up doing. Can I just forward the port on my local machine using iptables? I tried:
sudo iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 5000 -j REDIRECT --to-port 23
and
sudo iptables -t nat -I OUTPUT --src 0/0 -p tcp --dport 5000 -j REDIRECT --to-ports 23
but these didn't work...
Note that:
$ sudo iptables -t nat -L
Chain PREROUTING (policy ACCEPT)
target prot opt source destination
REDIRECT tcp -- anywhere anywhere tcp dpt:5000 redir ports 23
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
REDIRECT tcp -- anywhere anywhere tcp dpt:5000 redir ports 23
Chain POSTROUTING (policy ACCEPT)
target prot opt source destination
