Disabling IPv6 under a 2.6 kernel
Sometimes you might have a host which you wish to disable IPv6 upon, this can be useful if you're having DNS timeouts when software attempts to resolve hostnames, and for other reasons.
To disable IPv6 it should be as simple as adding the lines
alias net-pf-10 off
alias ipv6 off
to /etc/modprobe.d/00local (creating the file if it exists).