To check listening port on CentOS 7, you can do it by "netstat" simply, or you can try it by "ss". I was easily able to check which port is open or not on CentOS 7.
# netstat -tulnp
The above shows its result like below:
# netstat -tulnp Active Internet connections (only servers) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0.0.0:25 0.0.0.0:* LISTEN 2755/master tcp 0 0 127.0.0.1:6379 0.0.0.0:* LISTEN 2104/redis-server 1 tcp 0 0 0.0.0.0:11211 0.0.0.0:* LISTEN 2086/memcached tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 2088/sshd tcp6 0 0 :::25 :::* LISTEN 2755/master tcp6 0 0 :::8090 :::* LISTEN 29399/java tcp6 0 0 :::28090 :::* LISTEN 4248/java tcp6 0 0 :::443 :::* LISTEN 25560/httpd tcp6 0 0 :::28091 :::* LISTEN 4766/java tcp6 0 0 127.0.0.1:8000 :::* LISTEN 29399/java tcp6 0 0 127.0.0.1:28000 :::* LISTEN 4248/java tcp6 0 0 127.0.0.1:28105 :::* LISTEN 2806/java tcp6 0 0 :::3306 :::* LISTEN 2651/mysqld tcp6 0 0 :::11211 :::* LISTEN 2086/memcached tcp6 0 0 :::80 :::* LISTEN 25560/httpd tcp6 0 0 :::28180 :::* LISTEN 2806/java tcp6 0 0 :::22 :::* LISTEN 2088/sshd udp 0 0 127.0.0.1:323 0.0.0.0:* 1807/chronyd udp 0 0 0.0.0.0:11211 0.0.0.0:* 2086/memcached udp6 0 0 ::1:323 :::* 1807/chronyd udp6 0 0 :::11211 :::* 2086/memcached
# ss -nutlip
The above shows its result like below:
# ss -nutlp
Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port
udp UNCONN 0 0 127.0.0.1:323 *:* users:(("chronyd",pid=1807,fd=1))
udp UNCONN 0 0 *:11211 *:* users:(("memcached",pid=2086,fd=28))
udp UNCONN 0 0 ::1:323 :::* users:(("chronyd",pid=1807,fd=2))
udp UNCONN 0 0 :::11211 :::* users:(("memcached",pid=2086,fd=29))
tcp LISTEN 0 100 *:25 *:* users:(("master",pid=2755,fd=13))
tcp LISTEN 0 128 127.0.0.1:6379 *:* users:(("redis-server",pid=2104,fd=4))
tcp LISTEN 0 128 *:11211 *:* users:(("memcached",pid=2086,fd=26))
tcp LISTEN 0 128 *:22 *:* users:(("sshd",pid=2088,fd=3))
tcp LISTEN 0 100 :::25 :::* users:(("master",pid=2755,fd=14))
tcp LISTEN 0 32 :::8090 :::* users:(("java",pid=29399,fd=43))
tcp LISTEN 0 10 :::28090 :::* users:(("java",pid=4248,fd=22))
tcp LISTEN 0 128 :::443 :::* users:(("httpd",pid=30042,fd=6),("httpd",pid=30041,fd=6),("httpd",pid=30034,fd=6),("httpd",pid=29707,fd=6),("httpd",pid=29698,fd=6),("httpd",pid=29695,fd=6),("httpd",pid=29647,fd=6),("httpd",pid=29642,fd=6),("httpd",pid=29049,fd=6),("httpd",pid=28993,fd=6),("httpd",pid=28802,fd=6),("httpd",pid=25560,fd=6))
tcp LISTEN 0 128 :::28091 :::* users:(("java",pid=4766,fd=65))
tcp LISTEN 0 1 ::ffff:127.0.0.1:8000 :::* users:(("java",pid=29399,fd=75))
tcp LISTEN 0 1 ::ffff:127.0.0.1:28000 :::* users:(("java",pid=4248,fd=80))
tcp LISTEN 0 1 ::ffff:127.0.0.1:28105 :::* users:(("java",pid=2806,fd=336))
tcp LISTEN 0 128 :::3306 :::* users:(("mysqld",pid=2651,fd=15))
tcp LISTEN 0 128 :::11211 :::* users:(("memcached",pid=2086,fd=27))
tcp LISTEN 0 128 :::80 :::* users:(("httpd",pid=30042,fd=4),("httpd",pid=30041,fd=4),("httpd",pid=30034,fd=4),("httpd",pid=29707,fd=4),("httpd",pid=29698,fd=4),("httpd",pid=29695,fd=4),("httpd",pid=29647,fd=4),("httpd",pid=29642,fd=4),("httpd",pid=29049,fd=4),("httpd",pid=28993,fd=4),("httpd",pid=28802,fd=4),("httpd",pid=25560,fd=4))
tcp LISTEN 0 100 :::28180 :::* users:(("java",pid=2806,fd=264))
tcp LISTEN 0 128 :::22 :::* users:(("sshd",pid=2088,fd=4))