根据端口号查找服务，根据进程查找端口，查找开放的所有端口

[root@backup ~]# uname -r
2.6.32-696.el6.x86_64
[root@backup ~]# uname -m
x86_64
[root@backup ~]# cat /etc/redhat-release 
CentOS release 6.9 (Final)

telnet 10.0.0.41 22
nmap -p 22 10.0.0.41
nc 10.0.0.41 22
ss -lntup | grep 22
netstat -lntup | grep 22
lsof -i :22

ss -lntup | grep sshd
netstat -lntup | grep sshd

nmap -p 1-65535 10.0.0.41