Troubleshooting Network Ports
netstat command
- used to verify port connections on the local host for thins like file sharing or email ports being open on a remote server.
Examples
$ netstat
output
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 MACHINE_NAME:39054 xxx.xxx.xxx.xxx.bc:https TIME_WAIT
tcp 0 0 MACHINE_NAME:34028 xxx-xxx-xxx-xxx-xx:https ESTABLISHED
tcp 0 0 MACHINE_NAME:51304 IP_ADDRESS.bc:https TIME_WAIT
tcp 0 0 MACHINE_NAME:59256 IP_ADDRESS:https ESTABLISHED
tcp 32 0 MACHINE_NAME:47948 xxx-x-xxx-xx-xx.c:https CLOSE_WAIT
tcp 0 0 MACHINE_NAME:33262 IP_ADDRESS:https TIME_WAIT
tcp 0 0 MACHINE_NAME:39632 IP_ADDRESS.bc.g:http TIME_WAIT
tcp 0 0 MACHINE_NAME:34082 server-xx-xxx-xxx:https ESTABLISHED
tcp 0 0 MACHINE_NAME:42918 IP_ADDRESS.bc.g:https ESTABLISHED
tcp 0 0 MACHINE_NAME:36362 xxx-x-xxx-xx-xx.c:https ESTABLISHED
tcp 0 0 MACHINE_NAME:36024 IP_ADDRESS:https ESTABLISHED
tcp 0 0 MACHINE_NAME:51248 IP_ADDRESS.bc:https TIME_WAIT
tcp 0 0 MACHINE_NAME:59686 lb-xxx-xx-xxx-xx-:https ESTABLISHED
udp 0 0 MACHINE_NAME:bootpc RT-xxxxx-xxxxx:bootps ESTABLISHED
$ netstat -a
output includes UDP ports in the listening state
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 localhost:ipp 0.0.0.0:* LISTEN
tcp 0 0 localhost:postgresql 0.0.0.0:* LISTEN
tcp 0 0 localhost:5433 0.0.0.0:* LISTEN
tcp 0 0 localhost:domain 0.0.0.0:* LISTEN
tcp 0 0 b450m-ds3h:48790 76.237.120.34.bc.:https TIME_WAIT
tcp 32 0 b450m-ds3h:34028 ec2-34-200-107-25:https CLOSE_WAIT
tcp 32 0 b450m-ds3h:54880 ec2-3-225-38-57.c:https CLOSE_WAIT
tcp 0 0 b450m-ds3h:59256 104.18.13.33:https ESTABLISHED
tcp 32 0 b450m-ds3h:47948 ec2-3-225-38-57.c:https CLOSE_WAIT
tcp 0 0 b450m-ds3h:40312 lb-140-82-112-25-:https ESTABLISHED
tcp 0 0 b450m-ds3h:53530 server-54-230-202:https TIME_WAIT
tcp 0 0 b450m-ds3h:55882 1.97.149.34.bc.go:https TIME_WAIT
tcp 32 0 b450m-ds3h:54894 ec2-3-225-38-57.c:https CLOSE_WAIT
tcp 0 0 b450m-ds3h:44952 55.65.117.34.bc.g:https ESTABLISHED
tcp 0 0 b450m-ds3h:33860 ec2-44-214-229-86:https TIME_WAIT
tcp 0 0 b450m-ds3h:36024 75.75.77.4:https ESTABLISHED
tcp 0 0 b450m-ds3h:47268 123.208.120.34.bc:https TIME_WAIT
tcp 1 25 b450m-ds3h:59686 lb-140-82-112-25-:https CLOSING
tcp6 0 0 ip6-localhost:ipp [::]:* LISTEN
udp 0 0 localhost:domain 0.0.0.0:*
udp 0 0 b450m-ds3h:bootpc RT-AX58U-D978:bootps ESTABLISHED
udp 0 0 0.0.0.0:631 0.0.0.0:*
udp 0 0 0.0.0.0:mdns 0.0.0.0:*
udp 0 0 0.0.0.0:38292 0.0.0.0:*
udp6 0 0 [::]:60084 [::]:*
udp6 0 0 [::]:mdns [::]:*
raw6 0 0 [::]:ipv6-icmp [::]:*