[lug] Firewall spontaneously combusted???

David Morris lists at morris-clan.net
Fri Sep 10 17:39:42 MDT 2004

Ok, this is strange.

I recently moved and just got my new DSL link installed.  I
booted up my firewall system, an old Sparc LX, updated the
IP address for the external interface and in my firewall
script, then started up the firewall.

No joy.  No packets routed from my other computers at all.

The following commands should setup IP Masquerading on any
system with multiple interfaces where eth1 is the external

    cat 1 > /proc/sys/net/ipv4/ip_forward
    iptables --table nat --append POSTROUTING \
            --out-interface eth1 --jump SNAT \
            --to <external_ip>

I can run these commands on other systems and I get IP
Masquerading as expected.  Just before I moved I could run
it on the Sparc LX with as well and it worked there.

Now, I run it and I get *nothing*.

The packets are being received by the system and that no
packets are being lost no matter how big.  I can ping out of
both interfaces from the Sparc LX, and into it from other
computers on both sides.  The only thing I changed was the
physical location and the IP address of the external

Anyone have any ideas on what happend, or what I can do to
fix it?

System details:

    Hardware:  Sparc LX
    Distro:    Debian testing (sarge)
    Kernel:    2.4.20
    iptables:  version 1.2.6a


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