telnet 测试 使用

要ping的机器:
捕获telnet数据, 看是否数据有返回

tcpdump host 192.168.0.3 and  port 3306

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
16:18:16.382184 IP 192.168.0.3.48456 > 192.168.0.4.mysql: Flags [S], seq 4254011999, win 29200, options [mss 1410,sackOK,TS val 3886731780 ecr 0,nop,wscale 7], length 0
16:18:51.958653 IP 192.168.0.3.48458 > 192.168.0.4.mysql: Flags [S], seq 2079518222, win 29200, options [mss 1410,sackOK,TS val 3886767358 ecr 0,nop,wscale 7], length 0

telnet机器:
发送telnet 数据

timeout 3 telnet 192.168.0.4 3306

Trying 192.168.0.4...
telnet: connect to address 192.168.0.4: No route to host