一般情況下使用"telnet ip port"判斷端口通不通，其實測試方法不止這一種，還有很多種方法，下面小編給大家分享了幾種方法，具體內容請往下看：
准備環境
啟動一個web服務器，提供端口.
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[wyq@localhost ~]$ python -m SimpleHTTPServer 8080
Serving HTTP on 0.0.0.0 port 8080 ...
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用其它web服務器提供端口也一樣，由於python比較方便，這里就用它
1、使用telnet判斷
telnet是windows標准服務，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
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[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
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2）再連接存在的端口
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[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.
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2、使用ssh判斷
ssh是linux的標准配置並且最常用，可以用來判斷端口嗎？
用法: ssh -v -p port username@ip
-v 調試模式(會打印日志).
-p 指定端口
username可以隨意
1）連接不存在端口
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[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
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2）連接存在的端口
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[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
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不用-v選項也可以咯
3、使用wget判斷
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
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[root@localhost ~]
# wget ...:
---- ::-- http:
//
.../
Connecting to ...:... failed: Connection refused.
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2）連接存在的端口
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[root@localhost ~]
# wget ...:
---- ::-- http:
//
...:/
Connecting to ...:... connected.
HTTP request sent, awaiting response...
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4、使用端口掃描工具
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[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
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總結
提供端口服務，則使用了tcp協議，上面是以web服務器為例。如果服務器是更簡單的tcp服務器，三個工具同樣適用.
三個工具的共同點是：1.以tcp協議為基礎；2.能訪問指定端口. 遵循這兩點可以找到很多工具.
一般在windows下使用telnet比較方便，linux下個人就比較喜歡用wget.