服务器间网络连通性

常见的查看linux服务器之间网络连通性命令

1、telnet

telnet命令可以测试TCP/IP连接和端口的可用性 命令：telnet [目标服务器IP地址] [端口号]

一般网络通畅会返回一下信息：

Trying 192.168.5.141...
Connected to hostname (IP_address).

Escape character is '^]'.

如果还返回了“Connection closed by foreign host”，这表示网络访问关系是通的，但连接被远程主机关闭‌

网络不通

Trying 192.168.5.141...
telnet: Unable to connect to remote host: Connection refused

2、ping

ping命令用于测试主机之间的连通性。可以使用ping命令向远程主机发送网络请求，并接收回复。通过检查返回的回复时间和丢包率，可以判断主机是否可达以及网络连接是否正常 ‌命令：ping [IP地址]

一般ping通的情况：

PING 192.168.120.201 (192.168.120.201) 56(84) bytes of data.
64 bytes from 192.168.120.201: icmp_seq=1 ttl=64 time=0.309 ms
64 bytes from 192.168.120.201: icmp_seq=2 ttl=64 time=0.253 ms

一般ping不通的情况：

PING 192.168.5.141 (192.168.5.141) 56(84) bytes of data.
From 192.168.5.49 icmp_seq=1 Destination Host Unreachable
From 192.168.5.49 icmp_seq=2 Destination Host Unreachable
From 192.168.5.49 icmp_seq=3 Destination Host Unreachable

3、curl

curl命令可以测试网络连通性，主要用于发出网络请求并获取数据，然后显示在标准输出上 命令：curl -v [目标服务器IP地址]:[端口号]

网络连通的情况：

* Rebuilt URL to: 192.168.5.141:8848/
* Trying 192.168.5.141...
* TCP_NODELAY set
* Connected to 192.168.5.141 (192.168.5.141) port 8848 (#0)
> GET / HTTP/1.1
> Host: 192.168.5.141:8848
> User-Agent: curl/7.58.0
> Accept: */*
>
< HTTP/1.1 404
< Content-Type: text/html;charset=utf-8
< Content-Language: en
< Content-Length: 431
< Date: Tue, 03 Dec 2024 06:44:44 GMT
<
* Connection #0 to host 192.168.5.141 left intact

Connected to 192.168.5.141 (192.168.5.141) port 8848 (#0) 表示curl成功连接到指定的IP地址和端口号。 http返回的404；只能说明服务器无法找到客户端请求的资源，而不能代表网络不通

网络不通的情况

* Rebuilt URL to: 192.168.5.141:8848/
* Trying 192.168.5.141...
* TCP_NODELAY set
* connect to 192.168.5.141 port 8848 failed: Connection timed out
* Failed to connect to 192.168.5.141 port 8848: Connection timed out
* Closing connection 0
curl: (7) Failed to connect to 192.168.5.141 port 8848: Connection timed out

如果是“Connection timed out”，则需要检查网络延迟或者是否存在网络设备（如路由器或防火墙）阻止了连接 如果是“Connection refused”，则需要检查服务器端的服务是否正在运行，或者防火墙设置是否正确

​4、nc

nc命令是一个强大的网络工具，用于检查和测试网络连接。 命令：nc -zv [目标IP] [端口号] -z：参数告诉 nc 命令只扫描监听端口 -v：输出交互或出错信息

网络连通的情况下

Connection to 192.168.5.141 8848 port [tcp/*] succeeded!

网络不通

nc: connect to 192.168.5.141 port 80 (tcp) failed: Connection timed out

5、nmap

nmap命令用于网络扫描和安全审计的工具，可以检查主机的开放端口和服务

命令：nmap -p [端口号] [目标IP地址]

一般网络通时返回：

Starting Nmap 7.91 ( https://nmap.org ) at 2024-12-04 10:00 CST
Nmap scan report for 192.168.5.141
Host is up (0.00020s latency).

PORT STATE SERVICE
8080/tcp open http

Nmap done: 1 IP address (1 host up) scanned in 0.04 seconds

一般网络不通时：

Starting Nmap 7.91 ( https://nmap.org ) at 2024-12-04 10:01 CST
Nmap scan report for 192.168.5.141
Host is up (0.00025s latency).

PORT STATE SERVICE
8080/tcp closed http

Nmap done: 1 IP address (1 host up) scanned in 0.04 seconds