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)
http://thread.gmane.org/gmane.linux.CentOS.general/119342/focus9347
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
1

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 0.0.0.0, 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

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