翻譯自：
How to Test Port[TCP/UDP] Connectivity from a Linux Server (文件 ID 2212626.1)
適用於：
Linux OS - Version Oracle Linux 5.0 to Oracle Linux 6.8 [Release OL5 to OL6U8]
Information in this document applies to any platform.
目標：
在Linux伺服器上檢查TCP/UDP埠的連通性。
解決方案：
telnet和nc 是用來測試埠連通性的一般工具。
telnet可以測試tcp埠的連通性。
nc可以測試tcp和udp埠的連通性。
請確保telnet和nc工具已經安裝

# yum install nc
# yum install telnet

測試tcp埠的連通性：
語法如下：

telnet <hostname/IP address> <port number>

如下是連通成功的例子：

# telnet 192.118.20.95 22
Trying 192.118.20.95...
Connected to 192.118.20.95.
Escape character is '^]'.
SSH-2.0-OpenSSH_6.6.1

Protocol mismatch.
Connection closed by foreign host.

 

如下是連通不成功的例子：

# telnet 192.118.20.95 22
Trying 192.118.20.95...
telnet: connect to address 192.118.20.95: No route to host

使用nc命令來測試tcp埠的連通性：
語法：

nc -z -v <hostname/IP address> <port number>

如下是連通成功的例子：

# nc -z -v 192.118.20.95 22
Connection to 192.118.20.95 22 port [tcp/ssh] succeeded!

如下是連通不成功的例子：

# nc -z -v 192.118.20.95 22
nc: connect to 192.118.20.95 port 22 (tcp) failed: No route to host

使用nc命令來測試udp埠的連通性：
語法：

nc -z -v -u <hostname/IP address> <port number>

# nc -z -v -u 192.118.20.95 123
Connection to 192.118.20.95 123 port [udp/ntp] succeeded!