Bug 218508 - Tunneling and aliases using the tun device, reusing a destination address works with IPv4, but not IPv6
Summary: Tunneling and aliases using the tun device, reusing a destination address wor...
Status: New
Alias: None
Product: Base System
Classification: Unclassified
Component: kern (show other bugs)
Version: 11.0-RELEASE
Hardware: Any Any
: --- Affects Some People
Assignee: freebsd-net mailing list
Depends on:
Reported: 2017-04-09 08:29 UTC by Christian Sturm
Modified: 2017-04-09 10:30 UTC (History)
0 users

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Description Christian Sturm 2017-04-09 08:29:27 UTC
I can create a tun device by using:

ifconfig tun0 create
ifconfig tun 
ifconfig tun alias
ifconfig up

This works great and allows me to use the and have it tunneled over the second (aliased) tunnel when I set up the correct route using /sbin/route add -net -iface tun0.

I have this setup, using IPv6 only working as it is supposed to. To explain what I am am actually achieving with this: In the background I am using BGP over a one-to-one VPN software using the tunnel interface.

Doing the same thing on IPv6, however doesn't work when I add an alias, using the same destination address twice:

ifconfig tun0 inet6 fdaa:abc:abc:abc::1 fe80::111:0 prefixlen /128
ifconfig tun0 inet6 alias fe80::111:1 fe80::111:0 prefixlen /128
ifconfig: ioctl (SIOCAIFADDR): File exists

Using another destination address this works however. Since this works on IPv4 I'd expect it to work here as well.