一般情况下使用"telnet ip port"判断端口通不通，其实测试方法不止这一种，还有很多种方法，具体内容请往下看： 准备环境 启动一个web服务器，提供端口.

[wyq@localhost ~]$ python -m SimpleHTTPServer 8080
Serving HTTP on 0.0.0.0 port 8080

用其它web服务器提供端口也一样，由于python比较方便，这里就用它 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

[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

[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

[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

[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

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

2）连接存在的端口

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

4、使用端口扫描工具

[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