UDP Redirects

[Jim Redman <jim@ergotech.com>]

I have a system that is sending UDP packets to port 995 at about 100 
packets/second.  I want to redirect these to 1995 so that I can listen 
on an unpriveledged port.  So I:

iptables -t nat -A PREROUTING -p udp --dport 995 \
     -j REDIRECT --to-port 1995

This seems to work some of the time, but most of the time not.  It 
seems to work better when the connection is across a VPN which limits 
that packets to about 5-10/second.  So I assume that I've hit some 
limit, however this (and a number of variants) don't seem to help:

iptables -t nat -I PREROUTING -m limit --limit 1000/s \
     --limit-burst 1000 -j ACCEPT

Am I missing something obvious?  Any suggestions?

Thanks,

Jim

-- 

Jim Redman
(505) 662 5156 x85
http://www.ergotech.com