準備環境
啓動一個web服務器，提供端口.
[wyq@localhost ~]$ python -m SimpleHTTPServer 8080 Serving HTTP on 0.0.0.0 port 8080 ...
用其它web服務器提供端口也一樣，由於python比較方便，這裏就用它
1、使用telnet判斷
telnet是windows標準服務，可以直接用；如果是linux機器，需要安裝telnet.用法:telnet ip port
1）先用telnet連接不存在的端口
[root@localhost ~]# telnet 10.0.250.3 80 Trying 10.0.250.3... telnet: connect to address 10.0.250.3: Connection refused #直接提示連接被拒絕
2）再連接存在的端口
[root@localhost ~]# telnet localhost 22 Trying ::1... Connected to localhost. #看到Connected就連接成功了 Escape character is '^]'. SSH-2.0-OpenSSH_5.3 a Protocol mismatch. Connection closed by foreign host.
2、使用ssh判斷
ssh是linux的標準配置並且最常用，可以用來判斷端口嗎？用法:ssh -v -p port username@ip-v 調試模式(會打印日誌).-p 指定端口username可以隨意
1）連接不存在端口
[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）連接存在的端口
[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選項也可以咯
3、使用wget判斷（curl同理）
wget是linux下的下載工具，需要先安裝.用法:wget ip:port
1）連接不存在的端口
[root@localhost ~]# wget ...: ---- ::-- http://.../ Connecting to ...:... failed: Connection refused.
2）連接存在的端口
[root@localhost ~]# wget ...: ---- ::-- http://...:/ Connecting to ...:... connected. HTTP request sent, awaiting response...