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From: coot@coot.me
To: "wireguard@lists.zx2c4.com" <wireguard@lists.zx2c4.com>
Subject: WireGuard invalid MAC
Date: Sun, 25 Sep 2022 11:20:08 +0000	[thread overview]
Message-ID: <tc_RJxAHLCkuwnH-zzqG_kRpINdKQPkHV2EcHxd9Hvg35zKUqTjSD1enVM8UAEBeURm-4aBHxJEadNfVqn7ZRxyV2BAKrarPa5cL_hKhpB4=@coot.me> (raw)


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Hello,

I configured wireguard so I can access my home server from a laptop.

When the laptop is using its eth0 interface to transport wireguard protocol messages it works fine, but when I switch it off and use wlan0 (which is using a different ISP), on the server side the kernel logs:

Keypair 20 destroyed for peer 2
Keypair 21 created for peer 2
Invalid MAC of handshake, dropping packet from ...

I am using a ddns to setup the endpoint on the laptop.  It's not a connection issue, as packets are reaching the server, but somehow the message authentication code (MAC) is not right after switching the interfaces.  Any clues how could I investigate this further?

Client config:
```
[Interface]
Address = 10.0.0.3/24
ListenPort = 5000
PrivateKey = <client_private_key>

[Peer]
PublicKey = <server_pubic_key>
AllowedIPs = 10.0.0.1/32
Endpoint = <dynamic domain name>:5000
```

Server config:
```
[Interface]
Address = 10.0.0.1/24
ListenPort = 5000
PrivateKey = <server_private_key>

[Peer]
PublicKey = <client_public_key>
AllowedIPs = 10.0.0.3/32
```

When the laptop is using wlan0, the server receives a packet `Handshake Initiation`, which is not replied.  When the laptop is using eth0 it just sends messages of type `Transport Data` (both observed with a tcpdump).

Regards,
Marcin

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                 reply	other threads:[~2022-09-28 10:35 UTC|newest]

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