How To Disable Ipv6

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Hi all,

I’m pretty new to CentOS. I am working with a newly set-up server:

[cbearden@host ~]$ lsb_release -a LSB Version:
:core-4.0-amd64:core-4.0-noarch:graphics-4.0-amd64:graphics-4.0-noarch:printing-4.0-amd64:printing-4.0-noarch Distributor ID: CentOS
Description: CentOS release 6.3 (Final)
Release: 6.3
Codename: Final

I’m trying to solve this problem (X11 forwarding)
for myself.

But disabling ipv6 and adding

AddressFamily inet

to my sshd config didn’t fix the problem. Oddly enough, the output of

netstat -an

suggests that ipv6 is still enabled:

tcp 0 0 :::22 :::* LISTEN

even though

[cbearden@PostgreSQL ~]$ cat /proc/sys/net/ipv6/conf/all/disable_ipv6

This is after a reboot. Am I right that the /proc file suggests that ipv6 is disabled while netstat suggests that it isn’t?

Thanks, Chuck

4 thoughts on - How To Disable Ipv6

  • Thanks to Mark, Barry, and Johnny for their swift responses.

    I tried the steps at the wiki page above, but no joy. In particular, when I
    restart sshd, it appears that the ‘stop’ part fails:

    # /etc/init.d/sshd restart Stopping sshd: [FAILED]
    Starting sshd: [ OK ]

    Despite altering both values via sysctl and adding the AddressFamily line and uncommenting ListenAddress, sshd appears still to be listening on :::22. Other processes are still listening on ipv6-bound ports as well.

    Do I need to explicitly remove the ipv6 kernel module? I probably can’t while some daemons are bound to ::: ports. Sorry if I’m being dense here.

    I don’t know if this makes any difference, but the CentOS system is running in a VM. It’s not a setup I chose or ultimately control.

    Thanks, Chuck