DNAT what i am doing wrong ???

DNAT what i am doing wrong ???

[Czezz]

Hello everyone,

here is description of my situation:

my host is behind NAT server (Linux 2.4.x). By default, INPUT and
FORWARD is DROP. OUTPUT is ACCEPT.
There are maden some rules that allow to send/receive mail and for
PROXY server traffic.

Anyway, I want to connect to some server in the external net (
internet). Thatx to command:

   iptables -A FORWARD -i eth1 -j LOG --log-prefix "IPT:UnhandledForward:"

I found in syslog lines like this:

   Oct 16 19:05:59 slack kernel: IPT:UnhandledForward:IN=eth1 OUT=ppp0 SRC=192.168.1.251 DST=62.111.129.3 LEN=36 TOS=0x00 PREC=0x00 TTL=127 ID=17885
PROTO=UDP SPT=23083 DPT=13073 LEN=16
   Oct 16 19:07:44 slack kernel: IPT:UnhandledForward:IN=eth1 OUT=ppp0 SRC=192.168.1.251 DST=62.111.129.3 LEN=36 TOS=0x00 PREC=0x00 TTL=127 ID=18107
PROTO=UDP SPT=23083 DPT=13073 LEN=16
   Oct 16 19:10:27 slack kernel: IPT:UnhandledForward:IN=eth1 OUT=ppp0 SRC=192.168.1.251 DST=62.111.129.3 LEN=36 TOS=0x00 PREC=0x00 TTL=127 ID=18888
PROTO=UDP SPT=23083 DPT=13073 LEN=16
   Oct 16 19:11:08 slack kernel: IPT:UnhandledForward:IN=eth1 OUT=ppp0 SRC=192.168.1.251 DST=62.111.129.3 LEN=36 TOS=0x00 PREC=0x00 TTL=127 ID=19078
PROTO=UDP SPT=23083 DPT=13073 LEN=16

...so why in this situation I tryed to just FORWARD ports: SPT=23083
and DPT=13073. Unfortunately it wont work :(.

This is what I added:

   iptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT
   iptables -A FORWARD -i eth1 -p udp -m multiport --dport 13073,23083 -j ACCEPT

Dont know realy why it didnt work( maybe someone can explain me that,
because I use similar construction for SMTP and POP3 and it works
perfect)

Anyway i tryed to make DNAT.

I added the following lines:

   iptables -t nat -A PREROUTING -p tcp -i ppp0 --dport 13073 -j DNAT --to 192.168.1.251:23083
   iptables -A FORWARD -p tcp -d 192.168.1.251 --dport 23083 -j ACCEPT
   iptables -t nat -A PREROUTING -p udp -i ppp0 --dport 13073 -j DNAT --to-destination 192.168.1.251:23083
   iptables -A FORWARD -p udp -d 192.168.1.251 --dport 23083 -j ACCEPT

...and this method failed too :(

Can anyone give me an hand how to resolve this problem - i will be in
debt forever.

PS.

Please say if any of my description is not understood

-- 
Best regards,