Reboots

Servers have to be rebooted periodically to, among other reasons, make use of newly installed kernel versions.

Common problems

NIC shuffling by cloud providers

Some cloud providers think its funny to re-assign NIC names upon reboots - eth0 becomes eth2, eth2 becomes eth1 and eth2 becomes eth0.

This messes heavily with shorewall, which relies on NIC names to stay reboot-persistent.

If in doubt, disable shorewall before a reboot, like so:

root@server ~ # editor /etc/shorewall/shorewall.conf

Disable shorewalls startup:

STARTUP_ENABLED=No

Then reboot the server. It will boot with shorewall disabled.

To check if enabling shorewall will cause problems, do the following:

root@server ~ # editor /etc/shorewall/shorewall.conf
# Set STARTUP_ENABLED=Yes again
root@server ~ # tmux
root@server ~ # shorewall restart; sleep 30; shorewall clear

If you do not experience any problems within those 30 seconds, like services being unreachable or your SSH connection not working anymore, you can keep shorewall enabled.

Otherwise use ip a to view the network interfaces and their respective IPs and refer to /etc/shorewall/interfaces to check if the interfaces are different after the reboot.