Use netstat
netstat -nape can list all ports connection has been established and listening states
For embedded busybox, netstat command may not list the name of the program to open the port, there are two methods:
- Configuring busybox
Recompile busybox, supported the -p option lists the name of the program
2. The / proc file system to find
View all tcp ports open system
a）cat /proc/net/tcp
local_address column is ip: port, here are the hexadecimal
inode: open socket corresponding inode
b) Find inodeno corresponding process ID
for dir in `find /proc/ -name "fd"`; do ls -l $dir | grep 'socket\:\[13849\]' && echo $dir;done
c) process number to get the name of the process according to
head -n 1 /proc/2135/status
3841 As can be seen, for the band 10 to 14,401, the program opens the port named sshd
Also by this method can be viewed udp open ports, netstat program through the above process is actually open port information displayed
For the client side, the method is not applicable, then we should use a log function or TCPdump iptables tool, iptables invalid output prints out all dropped packets, which will see the port number for
