UDP 4000
Synopsis
- Legacy Mirabilis ICQ (early ICQ clients) used UDP port 4000 for client-to-server communication and some peer-related functions; many firewall guides from that era explicitly required UDP 4000 open for ICQ to work.
- Port 4000/udp is registered by IANA as “terabase,” used by the Terabase database service in certain legacy commercial deployments.
Observed activity
Last 30 days
Detailed chart