lsof

lists open files (including network connections)

COMMAND   PID USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
sshd     1023 root    3u  IPv4  12345      0t0  TCP *:22 (LISTEN)
chrome   2456 user   45u  IPv4  56789      0t0  TCP 192.168.1.10:52344->142.250.74.78:443
bash     3001 user    1u   CHR  136,0      0t0  /dev/pts/0

• lsof -i - Network Connections
• lsof -p - Filter by Process