I have IPv6 disabled in Internet Settings for this eth0 connection (Linux Mint) yet IPv6 addresses are still shown in the output of ifconfig. I have come to believe that it is best when using Tor to have IPv6 disabled for reasons of security. Do you agree? Is there a better, more fail safe way to completely disable IPV6 so even if Tor config files get compromised, IPv6 cannot be used? Here is my ifconfig. I would like to not see those IPv6 addresses.

mint@mint ~ $ ifconfig
eth0      Link encap:Ethernet  HWaddr 00:XX:XX:XX:XX:XX  
      inet addr:  Bcast:  Mask:
      inet6 addr: XXXXX:e825/64 Scope:Global
      inet6 addr: XXXXX:e825/64 Scope:Link
      inet6 addr: XXXXX:422a/64 Scope:Global
      RX packets:29311 errors:0 dropped:0 overruns:0 frame:0
      TX packets:17058 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:1000 
      RX bytes:33554675 (33.5 MB)  TX bytes:3450446 (3.4 MB)

lo        Link encap:Local Loopback  
      inet addr:  Mask:
      inet6 addr: ::1/128 Scope:Host
      UP LOOPBACK RUNNING  MTU:65536  Metric:1
      RX packets:40397 errors:0 dropped:0 overruns:0 frame:0
      TX packets:40397 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:0 
      RX bytes:13958224 (13.9 MB)  TX bytes:13958224 (13.9 MB)

NOTE: Can someone also explain how to use this site's formatting options to format posts like this that contain log files or ifconfig stuff like this?

  • Hi Richard. I'm asking in the framework of using this setup for Tor, and for Tor only - so I consider it Tor-specific. I can reword it. I just assumed because I'm posting here that it's obvious that this is about my network config for Tor. :) – Toraclease Mar 20 '16 at 19:33
  • @RichardHorrocks it is about not just Tor - in some cases I've seen alot of weird IPv6-related glitches even if it was not in use by any of the parts of a box, but just was not disabled and "something happened". – Alexey Vesnin Mar 21 '16 at 13:06
  • This is the config for the interface, which is used by any application wanting to use your network connection, regardless of the fact you only use the system for running Tor. If you want to change the interface's set-up, you'll have to do that independently of any of the settings in Tor. Tor itself can limit how it uses the interface - e.g. by setting some Tor config to exclude IPV6 traffic - but your questions are about the interface in general, and are invariant of your using Tor. Sorry to be a pain :-\ – Richard Horrocks Mar 21 '16 at 14:31
  • I can see both sides here. It's seems to be a grey area with a nod toward being Tor relevant. Here's a sound deductive argument based on premises that are 100% true. IPV6 does pose a potential security risk when enabled while using Tor. Tor's config files have been known to be compromised and altered by either some adversary or bug. Therefore it is of relevance to discuss how to disable IPV6 and/or other protocols outside the scope of Tor for the very sake of running Tor securely. Ifconfig is the very means to determine what protocols are enabled. continued.... – Toraclease Mar 21 '16 at 19:56
  • It might be wise, depending on the IPV6 threat model to disable IPV6 at the kernel. This can be done via sysctl $ sudo gedit /etc/sysctl.conf Add the following lines to the end of the file. Save, then close the file. # IPv6 disabled net.ipv6.conf.all.disable_ipv6 = 1 net.ipv6.conf.default.disable_ipv6 = 1 net.ipv6.conf.lo.disable_ipv6 = 1 restart sysctl with $ sudo sysctl -p check ifconfig. no IPV6 addresses should be listed. There, I figured it out on my own. You can delete this now. Thanks. – Toraclease Mar 21 '16 at 20:06

if you have ipv6 enabled anywhere - it will be appearing in ifconfigs everywhere, it's OK. it's just unconfigured and will not be used. To format just make a newline and use leading spaces - and see below a live preview

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