Port Forwarding with netfilter 1.0, big problems

[Eric Gandt]

Ok so I want to forward a port, sounds easy, but it does not work.  According
to everything I have read all I need is to add the following lines to the
masquerading set:
/usr/local/bin/iptables -A PREROUTING -t nat -p udp -d [external IP] \
--dport 27960 -j DNAT --to 192.168.0.5
/usr/local/bin/iptables -A PREROUTING -t nat -p tcp -d [external IP] \
--dport 27960 -j DNAT --to 192.168.0.5

Then it shoulw work, but it does not if I look at my current tables I get:

[root ~]# iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
DROP       all  --  anywhere             anywhere           state INVALID,NEW


Chain FORWARD (policy DROP)
target     prot opt source               destination         
ACCEPT     all  --  anywhere             anywhere           state
NEW,RELATED,ESTABLISHED 
ACCEPT     all  --  anywhere             anywhere           state
RELATED,ESTABLISHED 
DROP       all  --  anywhere             anywhere           state INVALID,NEW


Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         
[root ~]# iptables -t nat -L PREROUTING
Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination         
DNAT       udp  --  anywhere             216.181.215.102    udp dpt:27960
to:192.168.0.5 
DNAT       tcp  --  anywhere             216.181.215.102    tcp dpt:27960
to:192.168.0.5 

If I telnet to port 27960 I get:

[root ~]# telnet [external IP} 27960
Trying [external IP}...
telnet: Unable to connect to remote host: Connection refused
[root ~]# telnet 192.168.0.5 27960
Trying 192.168.0.5...
Connected to 192.168.0.5.
Escape character is '^]'.
^]
telnet> q
Connection closed.

now a connection to the [external IP} should be passed through to 192.168.0.5,
which will accept connections, but it does not.  I have tried everything I can
think of, but it does not fix the problem.  I would be greatful to anyone who
could fix the problem and explain why other people can get this to work, but I
can not!

Eric Gandt
egandt@netscape.net

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