DATAPUISTOKEMISTI

Some notes from my experiments with fetching more than one IP address from DHCP for same physical ethernet adapter. Nothing too difficult and you don't even need netns for this, few policy route settings would be enough if dhclient (and especially dhclient-script) wouldn't be so broken. For example dhclient has nasty habit of hijacking udp/68 on all network interfaces rather than only those it controls. There's also issues in some cases due routing when DHCP server is not on local LAN but behind WAN like it's in corporate and ISP networks.

Dirty hack to renew DHCP lease on Cisco 881 if Internet access is lost. This can happen when Cisco has valid DHCP lease from ISP and then cable modem or DSL router is power cycled but switch between Cisco and upstream device keeps link-state up. Options are either to fix it manually (pull cable / change config / reboot Cisco) or hack something like below. I'm also pinging over VPN tunnel to Intranet as it would be shame to break this due Level 3 and Google blocking ICMP which might happen one day.