Sunday, October 11, 2015

turning off ipv6 under Linux

Anyone familiar with networking know that the available number public ipv4 addresses is pretty much dried up. So as time goes on the move to ipv6 will only grow. However at least in parts of the US home users may not want to switch just yet. My local provider has ipv6 enabled but the performance is horrible. Pages and downloads simply drag or just stalls. Since the OS will prefer ipv6 over ipv4 when available the only option is to disable it. First check to see if you are receiving an ipv6 address by pulling the interface info from terminal

rican-linux@xubuntu-MacBookPro:~$ ifconfig wlp3s0
wlp3s0       Link encap:Ethernet HWaddr
                   inet addr: Bcast: Mask:
                   inet6 addr: fe80::225:ff:fe4f:4961/64 Scope:Link
inet6 addr: 2602:306:8b30:a310:225:ff:fe4f:4961/64 Scope:Global
inet6 addr: 2602:306:8b30:a310::43/128 Scope:Global
                   RX packets:41182 errors:0 dropped:0 overruns:0 frame:624154
                   TX packets:21081 errors:0 dropped:0 overruns:0 carrier:0
                   collisions:0 txqueuelen:1000 
                   RX bytes:36444300 (36.4 MB) TX bytes:2165921 (2.1 MB)

Now to disable ipv6 globally you will need to add this statement to the end of the /etc/sysctl.conf file, net.ipv6.conf.all.disable_ipv6 = 1. Then run the command as root sysctl -p /etc/sysctl.conf. This will disable ipv6 on your system.

Hopefully in time as more places have better ipv6 support this option will not be needed.

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