[plug] firewall issue

[Daniel Pittman]

"Jon Miller" <jlmiller at mmtnetworks.com.au> writes:

> I don't mind writing by hand as these servers have been in place for over 8
> years and I've always done it that way.  Although I will say the next one
> I'm building I had plans to look into shorewall or another package.

*shrug*  I always figure it is better to ask — and, personally, I find
the savings in time and trouble well worth adding firehol. :)

> I'll try to explain what I need this to do.  The clients are using
> iPhones and wants access to their mail via the Internet.  The mail
> server is on a NetWare 6.5 server (GroupWise 6.5) which runs IMAP,
> POP3 and of course SMTP.  There is an Linux Gateway server in from of
> the NetWare server running iptables and other security apps, in front
> of this is a Cisco Router running it's firewall.  What I've done is
> open the imap ports on both the Cisco router and Linux gateway.  What
> is supposed to happen is once the packets gets pass the Cisco router
> (which I know it is) because running tshark on the internal interface
> I can see packets hitting the INT_IFACE. So this may be more of a
> forwarding issue.  Do you agree?

Yup.  That sounds about right.  So, assuming you fixed that second
iptables command do you still see the problem?

Do you see packets going out the second interface at all?

Also, can you post the tcpdump output from a single connection attempt
for both the internal and external interfaces?

(tcpdump -ni ethX port 143, where ethX is the internal and external
interfaces.)

How about the output of cat /proc/sys/net/ipv4/ip_forward

Regards,
        Daniel