From: Nico Schottelius <nico.schottelius@ungleich.ch>
To: Diyaa Alkanakre <diyaa@diyaa.ca>
Cc: WireGuard mailing list <wireguard@lists.zx2c4.com>
Subject: Re: Wireguard uses incorrect interface - routing issue
Date: Fri, 21 Jun 2024 17:38:56 +0200 [thread overview]
Message-ID: <87jzii8fvz.fsf@ungleich.ch> (raw)
In-Reply-To: <O-vEobT--3-9@diyaa.ca> (Diyaa Alkanakre's message of "Fri, 21 Jun 2024 16:42:02 +0200 (CEST)")
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Diyaa,
this is about the *outside* tunnel IP address that wireguard uses to
establish connection, not about inside routing.
BR,
Nico
Diyaa Alkanakre <diyaa@diyaa.ca> writes:
> 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
>>
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Sustainable and modern Infrastructures by ungleich.ch
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prev parent reply other threads:[~2024-06-21 15:48 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
2024-06-21 15:18 ` Daniel Gröber
2024-06-21 15:38 ` Nico Schottelius [this message]
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