1.122 ``` 输出示例： ``` Trying 192.168.1.1 Connected to 192.168.1.1. Escape character is '^]'. ``` 注意事项： - 如果连接失败，可能表示端口未开放或防火墙阻止。 - `telnet` 不支持加密通信，适用于简单测试。 2.nc（Netcat） `nc` 是一个功能强大的网络工具，支持多种协议，包括TCP、UDP和ICMP。它比 `telnet` 更加灵活，适合测试多种网络服务。 使用方法： ```bash nc -zv
1.122 ``` 输出示例： ``` Connection to 192.168.
1.1port 22 [tcp] succeeded! ``` 注意事项： - `nc` 支持多协议，适合复杂网络测试。 - 通过 `-z` 参数可以快速检测端口是否开放。 3.netstat `netstat` 是一个用于查看网络连接状态的工具，可以显示当前所有活动的TCP和UDP连接。 使用方法： ```bash netstat -tuln | grep <端口> ``` 示例： ```bash netstat -tuln | grep 22 ``` 输出示例： ``` tcp6 0 0 192.168.1.1:22 0.0.0.0: LISTEN ``` 注意事项： - `netstat` 适用于查看端口状态，但不支持直接测试连接。 - 通过 `grep` 可以过滤特定端口的输出。 4.nmap `nmap` 是一个多功能的网络扫描工具，可以用于端口扫描、主机发现、服务发现等。它适用于大规模网络测试，尤其在发现未知端口时非常有用。 使用方法： ```bash nmap -p 22,80,443 192.168.1.1 ``` 输出示例： ``` Starting Nmap 7.91 ( https://nmap.org ) Nmap scan initiated for 192.168.
1.1host: 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