Check port occupancy in linux

How to check the port in Linux?

linux check port occupancy

Related recommendations: "Linux Tutorial"

1. lsof -i :Port number is used to check the usage of a certain port. For example, to check the usage of port 8000, lsof -i:8000

# lsof -i:8000
COMMAND   PID USER   FD   TYPE  DEVICE SIZE/OFF NODE NAME
lwfs    22065 root    6u  IPv4 4395053      0t0  TCP *:irdmi (LISTEN)

can see that port 8000 has been occupied by the lightweight file system forwarding service lwfs

2. Netstat -tunlp |grep port number, used to check the process status of the specified port number, such as checking the status of port 8000, netstat -tunlp |grep 8000

# netstat -tunlp 
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address               Foreign Address             State       PID/Program name   
tcp        0      0 0.0.0.0:111                 0.0.0.0:*                   LISTEN      4814/rpcbind        
tcp        0      0 0.0.0.0:5908                0.0.0.0:*                   LISTEN      25492/qemu-kvm      
tcp        0      0 0.0.0.0:6996                0.0.0.0:*                   LISTEN      22065/lwfs          
tcp        0      0 192.168.122.1:53            0.0.0.0:*                   LISTEN      38296/dnsmasq       
tcp        0      0 0.0.0.0:22                  0.0.0.0:*                   LISTEN      5278/sshd           
tcp        0      0 127.0.0.1:631               0.0.0.0:*                   LISTEN      5013/cupsd          
tcp        0      0 127.0.0.1:25                0.0.0.0:*                   LISTEN      5962/master         
tcp        0      0 0.0.0.0:8666                0.0.0.0:*                   LISTEN      44868/lwfs          
tcp        0      0 0.0.0.0:8000                0.0.0.0:*                   LISTEN      22065/lwfs

# netstat -tunlp | grep 8000
tcp        0      0 0.0.0.0:8000                0.0.0.0:*                   LISTEN      22065/lwfs

Explain the meaning of several parameters:

                                             

Attach a python port occupancy monitoring program, which can monitor whether the port of the specified IP is occupied.

 -t (tcp) 仅显示tcp相关选项
                                 -u (udp)仅显示udp相关选项
                                 -n 拒绝显示别名，能显示数字的全部转化为数字
                                 -l 仅列出在Listen(监听)的服务状态
                                 -p 显示建立相关链接的程序名

The execution result of this program is as follows:

#!/usr/bin/env python
# -*- coding:utf-8 -*-

import socket, time, thread
socket.setdefaulttimeout(3) #设置默认超时时间

def socket_port(ip, port):
    """
    输入IP和端口号，扫描判断端口是否占用
    """
    try:
        if port >=65535:
            print u'端口扫描结束'
        s=socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        result=s.connect_ex((ip, port))
        if result==0:
            lock.acquire()
            print ip,u':',port,u'端口已占用'
            lock.release()
    except:
        print u'端口扫描异常'

def ip_scan(ip):
    """
    输入IP，扫描IP的0-65534端口情况
    """
    try:
        print u'开始扫描 %s' % ip
        start_time=time.time()
        for i in range(0,65534):
            thread.start_new_thread(socket_port,(ip, int(i)))
        print u'扫描端口完成，总共用时：%.2f' %(time.time()-start_time)
#       raw_input("Press Enter to Exit")
    except:
        print u'扫描ip出错'

if __name__=='__main__':
    url=raw_input('Input the ip you want to scan: ')
    lock=thread.allocate_lock()
    ip_scan(url)

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