netstat
-a
Shows all sockets, including those that are listening.
-c Redisplay every 1 second until the user interrupts it.
-i Display information about all network interfaces, the format is the same as "ifconfig -e".
-n Displays network connections by replacing names with network IP addresses.
-r Display the core routing table, the format is the same as "route -e".
-t Displays the connection status of the TCP protocol.
-u Displays the connection status of the UDP protocol.
-v Display work in progress.
1. netstat -an | grep LISTEN
0.0.0.0 is the service that each IP has, and which IP is written is the service bound to that IP.
2. netstat -tln
Used to view the port usage of linux
3. /etc/init.d/vsftp start
Is used to start the ftp port ~!
4. netstat
View connected service ports (ESTABLISHED)
5. netstat -a
View all service ports (LISTEN, ESTABLISHED)
6. sudo netstat -ap
View all service ports and display the corresponding service program name
7. nmap <scan type> <scan parameter>
E.g:
nmap localhost
nmap -p 1024-65535 localhost
nmap -PT 192.168.1.127-245
when we use netstat
-apn When viewing network connections, you will find a lot of content similar to the following:
Proto Recv-Q Send-Q Local Address
Foreign Address State PID/Program name
tcp 0 52 218.104.81.152：7710
211.100.39.250：29488 ESTABLISHED 6111/1
It shows that the server has opened port 7710, so which program does this port belong to?
We can use the lsof -i:7710 command to query:
COMMAND PID USER FD TYPE DEVICE SIZE
NODE NAME
sshd 1990 root 3u IPv4 4836 TCP *：7710
（LISTEN） 54com.cn
In this way, we know that port 7710 belongs to the sshd program.