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Paul Rabinowitz wrote:

> here is the layout:
> 
> <172.17.201.0>------<router c2500>--<t1-circuit>---<router c7206>
> -----<172.20.0.0>----<masq (2.2x)>----<INTERNET>
> 
> PC's on the 172.20 network can access the internet fine
> PCs on the 172.17.201 network cannot
> 
> I can ping the masq box from the 172.17.201 network   -no problem
> I can ping the 172.17.201 network from the masq box   -no problem
> 
> here is my ipchains script:
> #
> #eth0 is the internal interface (good) (172.20 address)
> #eth1 is the external interface (bad) (REAL IP ADDRESS)
> #     
>       for f in /proc/sys/net/ipv4/conf/*/rp_filter; do echo 1 > $f; done
>       echo 1 > /proc/sys/net/ipv4/ip_forward
> #
>         ipchains -F
>         ipchains -A forward -s 172.20.0.0/16 -i eth1 -j good-bad
>         ipchains -A forward -s 172.17.201.0/24 -i eth1 -j good-bad
>         ipchains -A forward -i eth0 -j bad-good
>         ipchains -A forward -j DENY -l
> #        
>       ipchains -A good-bad -j MASQ
>       ipchains -A bad-good -j REJECT
> #
> ##########################
> #Access to firewall box itself   #
> ##########################
> #
> ipchains -A input -d 172.20.100.203 -j good-if
> ipchains -A input -d 63.66.240.106 -j bad-if
> #
> ipchains -A bad-if -i ! eth1 -j DENY -l
> ipchains -A bad-if -p TCP --dport 61000:65095 -j ACCEPT
> ipchains -A bad-if -p UDP --dport 61000:65095 -j ACCEPT
> ipchains -A bad-if -p ICMP --icmp-type pong -j ACCEPT
> ipchains -A bad-if -j icmp-acc
> ipchains -A bad-if -j DENY
> #
> ipchains -A good-if -i ! eth0 -j DENY
> ipchains -A good-if -p ICMP --icmp-type ping -j ACCEPT
> ipchains -A good-if -p ICMP --icmp-type pong -j ACCEPT
> ipchains -A good-if -p TCP --dport 23 -j ACCEPT
> ipchains -A good-if -j icmp-acc
> ipchains -A good-if -j DENY -l

looks ok except for the lack of user chain creation (-N) commands.
i'll assume you just left them out of the message for brevity.

what do the packets look like when you try to get out from the
172.17.201 network? do a "tcpdump -i eth0" and a "tcpdump -i eth1".
do any packet log messages appear in /var/log/messages when you try
this?

raf

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