IPv6 issues on BinaryLane caused by Linux “Privacy Extensions” (RFC 4941)


Some Linux distributions may enable IPv6 “Privacy Extensions” (RFC 4941) by default. BinaryLane IPv6 expects your VM to use the normal auto-configured (SLAAC) address shown in mPanel.

When privacy extensions are enabled, Linux will also generate one or more temporary IPv6 addresses. Your system may then try to use a temporary/random address for outbound connections instead of the stable address shown in mPanel. Because BinaryLane does not support using these temporary/privacy addresses, this can cause sporadic or persistent IPv6 problems (timeouts, intermittent connectivity, or services binding to an address that doesn’t work).

How to confirm privacy extensions are enabled (mngtmpaddr / temporary)


SSH into the server and run:

ip -6 addr show


If privacy extensions are enabled, you’ll typically see IPv6 addresses marked with flags such as temporary and/or mngtmpaddr. For example:

  • temporary indicates a temporary/privacy address exists

  • mngtmpaddr indicates the interface is managing temporary/privacy addresses (i.e. privacy extensions behaviour is active)

You may also check the kernel settings directly:

sysctl net.ipv6.conf.all.use_tempaddr sysctl net.ipv6.conf.default.use_tempaddr


Values of 1 or 2 mean temporary addresses are enabled (to some degree). 0 means disabled.

Fix: Disable IPv6 privacy extensions

Apply immediately (runtime)


Run as root:

sysctl -w net.ipv6.conf.all.use_tempaddr=0 sysctl -w net.ipv6.conf.default.use_tempaddr=0


Make persistent (recommended)


Instead of appending to /etc/sysctl.conf, it’s generally cleaner to create a dedicated sysctl drop-in:

cat >/etc/sysctl.d/60-disable-ipv6-privacy.conf <<'EOT'
net.ipv6.conf.all.use_tempaddr=0 net.ipv6.conf.default.use_tempaddr=0 EOT


Then apply:

sysctl --system


(Alternatively, sysctl -p /etc/sysctl.d/60-disable-ipv6-privacy.conf is fine.)

After applying the change


Within a few seconds, the OS should prefer the standard auto-configured IPv6 address (the one shown in mPanel) rather than using temporary/privacy addresses.

If you want to force things along without waiting, you can flush temporary global addresses on the main interface (replace eth0 as needed):

ip -6 addr flush dev eth0 scope global temporary


Re-run:

ip -6 addr show dev eth0


You should no longer see new temporary addresses being generated, and mngtmpaddr should no longer appear for the active global address behaviour.

Notes / optional per-interface setting

If you only want to apply this to a specific interface (e.g. eth0), you can also set:

sysctl -w net.ipv6.conf.eth0.use_tempaddr=0


But for most servers, disabling it for all + default is the simplest and avoids surprises on additional interfaces.