Disable IPV6 in Debian Lenny?

For the archive:
edit:

/etc/modprobe.d/aliases

By default you will have a line like this:

alias net-pf-10 ipv6

Replace that line with:

alias net-pf-10 off
alias ipv6 off

(The second line may/may not be required with newer (2.26.+) kernels, but it won’t hurt anything)

Also, while we’re at it, on your desktop machines, help out Firefox by disabling IPv6 there too. It’s simple, in the location bar enter:

about:config

Then search for:

network.dns.disableIPv6

and toggle its value to ‘true'