Buggy MTU with Wireguard (attached pcapng)

Buggy MTU with Wireguard (attached pcapng)

[alpha_one_x86]

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Hi,

I have wireguard interface "veth", and my real interface "eth0".

No bug with openvpn, but with wireguard on IPv4 for https, I have bug, 
see the attached file, the returned data is 3300byte, then Destination 
unreachable (Fragmentation needed).

Bug into wireguard? How fix this?

The ok.pcapng it's same https download do with openvpn.

Cheers,

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Re: Buggy MTU with Wireguard (attached pcapng)

[Vasili Pupkin]

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The TCP connection MSS is set to 1460 bytes and also Don't fragment flag 
is set. The server selects this MSS as a frame size on its side and 
packet is dropped, probably. If you are using linux router try to use 
this command "iptables -I FORWARD -p tcp --tcp-flags SYN,RST SYN -j 
TCPMSS --clamp-mss-to-pmtu" or be careful to set MTU on all client 
machines adapters correctly.


On 10.01.2020 1:05, alpha_one_x86 wrote:
>
> Hi,
>
> I have wireguard interface "veth", and my real interface "eth0".
>
> No bug with openvpn, but with wireguard on IPv4 for https, I have bug, 
> see the attached file, the returned data is 3300byte, then Destination 
> unreachable (Fragmentation needed).
>
> Bug into wireguard? How fix this?
>
> The ok.pcapng it's same https download do with openvpn.
>
> Cheers,
>
>
> _______________________________________________
> WireGuard mailing list
> WireGuard@lists.zx2c4.com
> https://lists.zx2c4.com/mailman/listinfo/wireguard


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