diff --git a/docs/2024.md b/docs/2024.md
index 453e1bd..8cc8abc 100644
--- a/docs/2024.md
+++ b/docs/2024.md
@@ -42,11 +42,24 @@ PostDown = iptables -t nat -D PREROUTING -p tcp -m tcp --dport <outer_port> -j D
 
 #### 检测客户端连通性
 
+nmap:
+
 ```shell
 nmap -6 -p <端口号> <IPv6地址>
 nmap -p <端口号> <IPv4地址>
 ```
 
+nc:
+
+```shell
+# TCP
+nc -l <port> # server
+nc <addr> <port> # client
+# UDP
+nc -u -l <port> # server
+nc -u <addr> <port> # client
+```
+
 ### 11.14
 
 #### 纯ipv6服务器访问ipv4