[Ubuntu-US-CA] All incoming ports blocked without iptables

[Tony Baechler]

Hi all,

I'm really stumped here.  I've tried everything I can think of but nothing
seems to work.  I really need help here!  I'm willing to try anything at
this point.

I am running Ubuntu 14.04.1 and have recently upgraded to the latest 3.13
kernel with security fixes.  I rebooted the server after the kernel upgrade
and now all ports are blocked.  I get an immediate "connection refused."
I've completely purged ufw, iptables, fail2ban and the Qemu packages just in
case.  I can get to the server with a rescue system and I can boot with KVM.
 When I boot this way, everything looks fine and the network seems normal.
I can connect to port 22 on localhost just fine.  When I reboot out of the
rescue system, everything is again blocked.  It's obviously something with
the network, but I don't know what.  Trying a 3.16 kernel made no
difference.  My daily cron jobs are running and Postfix is running, but it
isn't getting any incoming mail.  I restored my /etc/network/interfaces from
a known good backup.  I don't recall adding or changing anything related to
bridges or routing.

What else can I try?  I would give more information but I don't know where
else to look.  I've removed or purged any recent packages which might have
caused a problem.  It was fine until I rebooted, but I really don't know
what changed to cause the breakage.  Any thoughts?