From: Diyaa Alkanakre <diyaa@diyaa.ca>
To: Nico Schottelius <nico.schottelius@ungleich.ch>
Cc: WireGuard mailing list <wireguard@lists.zx2c4.com>
Subject: Re: Wireguard uses incorrect interface - routing issue
Date: Fri, 21 Jun 2024 16:42:02 +0200 (CEST) [thread overview]
Message-ID: <O-vEobT--3-9@diyaa.ca> (raw)
In-Reply-To: <878qyyim5k.fsf@ungleich.ch>
The better approach would be to exclude the IPs from your WireGuard AllowedIPs. I always exclude IPs if I can before doing policy based routing.
https://www.procustodibus.com/blog/2021/03/wireguard-allowedips-calculator/
Jun 21, 2024, 5:15 AM by nico.schottelius@ungleich.ch:
>
> Hello again,
>
> I'm sorry to flood the mailing list with wireguard bugs, but it seems
> there is yet another routing bug in wireguard - happy to be wrong, but
> here are my findings:
>
> a) system has source based routing on via ip rule:
>
> [11:07] server141.place10:~# ip rule ls
> 0: from all lookup local
> 32765: from 192.168.1.0/24 lookup 42
> 32766: from all lookup main
> 32767: from all lookup default
> [11:07] server141.place10:~# ip route sh table 42
> 194.5.220.0/24 via 192.168.1.254 dev eth1 proto bird metric 32
> 194.187.90.23 via 192.168.1.254 dev eth1 proto bird metric 32
> 212.103.65.231 via 192.168.1.254 dev eth1 proto bird metric 32
> [11:08] server141.place10:~#
>
> This should ensure that packets towards 194.187.90.23 travel via eth1.
>
> b) tcpdump for verification
>
> Using "tcpdump -ni any port 4000" I observe:
>
> 11:10:22.445638 eth0 Out IP 192.168.1.149.58591 > 194.187.90.23.4000: UDP, length 148
> 11:10:27.447026 eth0 Out IP 192.168.1.149.58591 > 194.187.90.23.4000: UDP, length 148
> 11:10:32.448329 eth0 Out IP 192.168.1.149.58591 > 194.187.90.23.4000: UDP, length 148
> 11:10:37.449719 eth0 Out IP 192.168.1.149.58591 > 194.187.90.23.4000: UDP, length 148
>
> c) Route in main table
>
> There is indeed a route in the main routing table that matches, too:
>
> [11:08] server141.place10:~# ip r get 194.187.90.23
> 194.187.90.23 via 10.5.2.123 dev eth0 src 192.168.1.149 uid 0
> cache
>
> d) ip rule not working (?)
>
> So from what I can observe it is that ip rule does not work together
> with wireguard / wireguard routing takes the route from main fib instead
> of from the separate table.
>
> I am not sure if this is related at all to the IP address binding bug,
> but it appears in a similar context from our tests.
>
> BR,
>
> Nico
>
> --
> Sustainable and modern Infrastructures by ungleich.ch
>
next prev parent reply other threads:[~2024-06-21 14:42 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-21 11:13 Nico Schottelius
2024-06-21 11:24 ` Nico Schottelius
2024-06-21 12:29 ` Daniel Gröber
2024-06-22 9:22 ` Nico Schottelius
2024-06-21 14:42 ` Diyaa Alkanakre [this message]
2024-06-21 15:18 ` Daniel Gröber
2024-06-21 15:38 ` Nico Schottelius
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