Debug linux networking...

networking.sh

# List all open connections
netstat -atp tcp | grep -i "listen"

# Proto Recv-Q Send-Q  Local Address          Foreign Address        (state)   
# tcp4       0      0  localhost.25035        *.*                    LISTEN

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# List all open ports
sudo lsof -i -P | grep -i "listen"

# COMMAND     PID      USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
# GitHub      850 grgarside   6u   IPv4 0x23c345381d089301      0t0  TCP localhost:25035 (LISTEN)