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i need to forward incoming port 69 to port 2112 with iptables on linux. i don't need any NAT etc. just accept incoming connections to port 2112 like it be 69 pot.

Thank you!

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up vote 1 down vote accepted

This should do what you want

iptables -t nat -A PREROUTING -p udp --dport 69 -j REDIRECT --to-port 2112
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And when i run your command nothing still applied to iptables. – Raspizdyay Aug 10 '12 at 12:54
@Raspizdyay: Did you list the correct table ? iptables -t nat -L ? – Iain Aug 10 '12 at 15:03
but why nat? there is no nat on my computer it is just an imput – Raspizdyay Aug 12 '12 at 9:11
@Raspizdyay: Port forwarding is address translation and takes place in the PREROUTING chain of the NAT table. – Iain Aug 12 '12 at 9:28

As well as the port forwarding, you also need an extra module loaded to handle tracking tftp connections. This can be done in testing by simply running

modprobe nf_conntrack_tftp

Making it permanent depends on the distro in use, but you generally just need to put it in /etc/modules so it will be loaded at boot.

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