Answers for "linux check for forwarded ports"

linux how to see ports in use

# Any of the following
sudo lsof -i -P -n | grep LISTEN
sudo netstat -tulpn | grep LISTEN
sudo lsof -i:22 # see a specific port such as 22
sudo nmap -sTU -O IP-address-Here

list of created ssh port forwarding

% sudo lsof -i -n | egrep '<ssh>'
ssh  19749  user  3u  IPv4 148088244   TCP x.x.x.x:39689->y.y.y.y:22 (ESTABLISHED)
ssh  19749  user  4u  IPv6 148088282   TCP [::1]:9090 (LISTEN)
ssh  19749  user  5u  IPv4 148088283   TCP 127.0.0.1:9090 (LISTEN)