by I'm running a firewall with a 2.2.6 kernel (slackware 4.0) and have IP
chains up and running for my small home network over the cable modem.
The only problem is with the pop3 mail.
My ISP (earthlink.net) has multiple mail servers aliased to
"mail.earthlink.net". Successive calls to nslookup return different
INDIVIDUAL addresses. In contrast, running nslookup on (for example)
www.altavista.com returns a list of addresses.
The ipchains rules look like:
ipchains -A input -i eth0 -p tcp ! -y -s $POP_SERVER 110 \
-d $EXTERNAL_IP 1025:65525 -j ACCEPT
ipchains -A output -i eth0 -p tcp -s $EXTERNAL_IP 1025:65535 \
-d $POP_SERVER -j ACCEPT
If I hard-code one of the "mail.earthlink.net" addresses as
$POP_SERVER in the IPCHAINS setups and on ALL the clients, this works.
However, it seems contrary to the spirit of the whole system . . .
.<g>
If I don't hard-code the address, the resolution of
"mail.earthlink.net" at run-time almost NEVER matches the one that
ipchains made at startup, so the packets are denied.
Any suggestions would be welcome . . . .
TIA . . .
Dan