Slow internet on Ubuntu 8.10

A week or so after updating to Intrepid on my work desktop, I started experiencing really slow internet connections. (around 100k/s). Tried a different network port – no change. Booted into windows, and got 2M/s. After perusing the ubuntu forums, I found this solution:

edit /etc/sysctl.conf and add:
net.ipv4.tcp_sack = 0
net.ipv4.tcp_window_scaling = 0

edit /etc/modprobe.d/aliases to remove:
alias net-pf-10 ipv6
and add:
alias net-pf-10 off
alias net-pf-10 off ipv6

This turns off IPv6, which seems rather heavy-handed, but disabling ipv6 in firefox alone didn’t fix the problem. I suspect that it was the result of a change somewhere in the school’s network, but dealing with their IT dept is like banging your head against a wall repeatedly. Hope this can help someone else with the same issue.

5 Responses to “Slow internet on Ubuntu 8.10”

  1. drhind Says:
    December 20th, 2008 at 7:30 pm

    Dude – you are my new hero!!!! This probably has been driving me nuts for months. The fix has increased the speed something like 500%!

  2. Mintux Says:
    December 30th, 2008 at 4:21 pm

    This solution only works when there is a badly configured router on the network which does not handle IPv6 packets properly.

    If routers on the local network are properly configured, it should make no difference (but then your internet shouldn’t be slow either).

  3. Mintux Says:
    December 30th, 2008 at 4:22 pm

    Oh yes, and it applies to any version of Ubuntu, not only 8.10.

  4. Chris Says:
    January 8th, 2009 at 1:52 pm

    Yes, to be perfectly clear: This will not make your DSL faster, or speed up your network in most cases. This is only if you’re stuck on a network out of your control (school, corporate, etc) that handles IPv4 improperly.

  5. imaginashawn Says:
    January 25th, 2009 at 10:22 pm

    After installing Ubuntu 8.10, my DSL internet connection was very slow. I was successful at correcting the problem by disabling ipv6. Here’s the right way:
    http://www.pcmech.com/article/how-to-fix-a-slow-internet-connection-in-ubuntu-710/
    Enjoy