如何测试TCP端口通不通(四种方法）

1、使用telnet判断

telnet是windows标准服务，可以直接用；如果是linux机器，需要安装telnet.

用法: telnet ip port

1）先用telnet连接不存在的端口

?

1 2 3

[root@localhost ~]# telnet 10.0.250.3 80 Trying 10.0.250.3... telnet: connect to address 10.0.250.3: Connection refused #直接提示连接被拒绝

2）再连接存在的端口

?

1 2 3 4 5 6 7 8

[root@localhost ~]# telnet localhost 22 Trying ::1... Connected to localhost. #看到Connected就连接成功了 Escape character is '^]'. SSH-2.0-OpenSSH_5.3 a Protocol mismatch. Connection closed by foreign host.

2、使用ssh判断

ssh是linux的标准配置并且最常用，可以用来判断端口吗？

用法: ssh -v -p port username@ip

-v 调试模式(会打印日志).

-p 指定端口

username可以随意

1）连接不存在端口

?

1 2 3 4 5 6 7 8 9

[root@localhost ~]# ssh 10.0.250.3 -p 80 ssh: connect to host 10.0.250.3 port 80: Connection refused [root@localhost ~]# ssh 10.0.250.3 -p 80 -v OpenSSH_5.3p1, OpenSSL 1.0.1e-fips 11 Feb 2013 debug1: Reading configuration data /etc/ssh/ssh_config debug1: Applying options for * debug1: Connecting to 10.0.250.3 [10.0.250.3] port 80. debug1: connect to address 10.0.250.3 port 80: Connection refused ssh: connect to host 10.0.250.3 port 80: Connection refused

2）连接存在的端口

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

[root@localhost ~]# ssh ... -p a ^] ^C [root@localhost ~]# ssh ... -p -v OpenSSH_.p, OpenSSL ..e-fips Feb debug: Reading configuration data /etc/ssh/ssh_config debug: Applying options for * debug: Connecting to ... [...] port . debug: Connection established. debug: permanently_set_uid: / debug: identity file /root/.ssh/identity type - debug: identity file /root/.ssh/identity-cert type - debug: identity file /root/.ssh/id_rsa type - debug: identity file /root/.ssh/id_rsa-cert type - debug: identity file /root/.ssh/id_dsa type - debug: identity file /root/.ssh/id_dsa-cert type - a ^C

不用-v选项也可以咯

3、使用wget判断

wget是linux下的下载工具，需要先安装.

用法: wget ip:port

1）连接不存在的端口

?

1 2 3

[root@localhost ~]# wget ...: ---- ::-- http://.../ Connecting to ...:... failed: Connection refused.

2）连接存在的端口

?

1 2 3 4

[root@localhost ~]# wget ...: ---- ::-- http://...:/ Connecting to ...:... connected. HTTP request sent, awaiting response...

4、使用端口扫描工具

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

[root@localhost ~]# nmap ... -p Starting Nmap . ( http://nmap.org ) at -- : CST Nmap scan report for ... Host is up (.s latency). PORT STATE SERVICE /tcp closed http MAC Address: B:A::CF:FD:D (Unknown) Nmap done: IP address ( host up) scanned in . seconds [root@localhost ~]# nmap ... -p Starting Nmap . ( http://nmap.org ) at -- : CST Nmap scan report for ... Host is up (.s latency). PORT STATE SERVICE /tcp open http-proxy MAC Address: B:A::CF:FD:D (Unknown) Nmap done: IP address ( host up) scanned in . seconds [root@localhost ~]# nmap ... Starting Nmap . ( http://nmap.org ) at -- : CST Nmap scan report for ... Host is up (.s latency). Not shown: closed ports PORT STATE SERVICE /tcp open ssh /tcp open rpcbind /tcp open http-proxy /tcp open unknown MAC Address: B:A::CF:FD:D (Unknown) Nmap done: IP address ( host up) scanned in . seconds