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Date: Tue, 2 Jan 2024 21:01:12 +0800
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A0MTU=E8=AE=A1=E7=AE=97?=
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---
 docs/config/outbounds/wireguard.md | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/docs/config/outbounds/wireguard.md b/docs/config/outbounds/wireguard.md
index 9b1b03f..0e44224 100644
--- a/docs/config/outbounds/wireguard.md
+++ b/docs/config/outbounds/wireguard.md
@@ -46,6 +46,24 @@ Wireguard 会在本地开启虚拟网卡 tun。使用一个或多个 IP 地址
 
 Wireguard 底层 tun 的分片大小。
 
+<details>
+<summary>MTU的计算方法</summary>
+
+一个wireguard数据包的结构如下
+
+```
+- 20-byte IPv4 header or 40 byte IPv6 header
+- 8-byte UDP header
+- 4-byte type
+- 4-byte key index
+- 8-byte nonce
+- N-byte encrypted data
+- 16-byte authentication tag
+```
+
+```N-byte encrypted data```即为我们需要的MTU的值，根据endpoint是IPv4还是IPv6，具体的值可以是1440(IPv4)或者1420(IPv6)，如果处于特殊环境下再额外减掉即可(如家宽PPPoE额外-8)。
+</details>
+
 > `reserved` \[ number \]
 
 Wireguard 保留字节。