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Re: debian-firewall: how do I let SMTP through with ipmasq ??

My setup is :  Internet ---[a.b.c.d MasqueradingFirewall] ---
[ MailServer]

On my firewall I have executed the command "ipmasqadm portfw -a -P tcp -L a.b.c.d
25 -R 25" so that incoming SMTP will be forwarded to machine  I don't seem to be able to send mail to the mailserver via the
masquerading firewall (eg. user@a.b.c.d should get redirected to
user@  It gets bounced back with unknown DNS host.  How can I test
that my firewall is letting through the SMTP packets ?

The IPMASQ FAQ (sect 7.31) says "You have to first understand that both IPFWADM
and IPCHAINS run *AFTER* the routing system has decided where to send a packet."
I assume this is true for portfw, so I don't need to setup a specific "ipchains
input" rule for that host/port".  Is that correct.

Assuming my "ipmasqadm portfw" command above is correct, is there any other
commands (ipmasqadm, ipchains, etc) that I need to run to get mail coming in to
my masqueraded mailserver ( ?

There is an example in section 7 of the IPCHAINS FAQ, but the servers in the
demilitarised zones have public IP addresses.  It purely uses IPCHIANS, not
portfw.  I think I need portfw because of the masquerading.  Is this correct ?

Brendan Simon.

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