我的局域网上有一台 Linux 服务器。我尝试连接其已知 IP 地址,结果如下:
scott@CN100819:~$ ssh [email protected]
ssh: connect to host 192.168.99.63 port 22: Resource temporarily unavailable
因此我当然尝试 ping 该地址来验证响应能力:
C:\Users\scottbailey>ping 192.168.99.63
Pinging 192.168.99.180 with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
因此我猜想服务器可能不知何故失去了与网络的连接。然而有趣的是——作为最后的努力,我运行了nmap
该地址……结果它居然可用了:
C:\Users\scottbailey>nmap 192.168.99.63
Starting Nmap 7.31 ( https://nmap.org ) at 2017-01-25 12:45 Atlantic Standard Time
Nmap scan report for 192.168.99.63
Host is up (0.0033s latency).
Not shown: 996 closed ports
PORT STATE SERVICE
22/tcp open ssh
23/tcp open telnet
80/tcp open http
443/tcp open https
MAC Address: 5C:77:57:00:3D:D2 (Haivision Network Video)
Nmap done: 1 IP address (1 host up) scanned in 14.50 seconds
当时我非常惊讶,所以我ssh
又试了一次,这次成功了。有人能解释为什么会发生这种情况吗?为什么ping
和命令在发挥其魔力ssh
之前无法与地址通信?nmap