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Asked: 2017-09-20 14:29:12 +0800 CST

Debian 9.1: Can't disable IPv6 autoconfig

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I've updated a machine to Debian 9.1 and everything seems to be fine, however I can't disable IPv6 autoconfig.

Background: I only want to use some specific IPv6 addresses on the machine that I'm defining in /etc/systemd/network/10-static-eth0.network:

[Match]
Name=eth0

[Network]
Address=2a04:52c0:xxx:xxx::xxx/48
Address=2a04:52c0:xxx:xxx::xxx/48
Address=2a04:52c0:xxx:xxx::xx/48
Gateway=2a04:52c0:xxx::1

Address=5.2.xxx.xxx/25
Address=5.2.xxx.xxx/25
Address=5.2.xxx.xxx/25
Gateway=5.2.xxx.xxx

To disable IPv6 autoconfig I added the following at the end of /etc/sysctl.conf:

net.ipv6.conf.default.autoconf=0
net.ipv6.conf.all.autoconf=0
net.ipv6.conf.eth0.autoconf=0

net.ipv6.conf.default.accept_ra=0
net.ipv6.conf.all.accept_ra=0
net.ipv6.conf.eth0.accept_ra=0

net.ipv6.conf.default.accept_dad=0
net.ipv6.conf.all.accept_dad=0
net.ipv6.conf.eth0.accept_dad=0

After rebooting there's no dynamic / autoconfig IPv6 address but after a while it appears on ip addr show:

inet6 2a04:52c0:xxxx:xxxx:xxxx:xxx:xxxx:1e3d/64 scope global mngtmpaddr noprefixroute dynamic 
   valid_lft 2590732sec preferred_lft 603532sec

How can I avoid this autoconfig IPv6 address and make sure only the static addresses get to work?

Thank you.

debian

1 Answers

  1. Best Answer

    I believe these addresses marked as mngtmpaddr and noprefixroute come from the IPv6 Privacy Extensions standard (RFC 4941) and are created by the kernel itself.

    You should be able to turn that feature off adding

    net.ipv6.conf.default.use_tempaddr=0
net.ipv6.conf.all.use_tempaddr=0
net.ipv6.conf.eth0.use_tempaddr=0

    to your /etc/sysctl.conf

    Hope it helps!

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