Is port 4000 (ICQ / Diablo II) dangerous?

Port 4000 is classified as medium risk. It is commonly exposed but consider using encrypted alternatives where available and monitor activity.

Should port 4000 be open on my firewall?

Port 4000 can be open but should be monitored closely. Keep the service updated and prefer encrypted alternatives where available.

What transport protocol does port 4000 use?

Port 4000 (ICQ / Diablo II) uses the TCP/UDP transport protocol and falls under the Messaging category.

:4000 (TCP/UDP)

ICQ / Diablo II

Medium Risk

TCP/UDP — Messaging

Port Overview

Port Number 4000

Service Name ICQ / Diablo II

Transport Protocol TCP/UDP

Category Messaging

Security Risk Medium

Port Range Registered (1024-49151)

What is Port 4000?

Port 4000 is associated with ICQ instant messaging (legacy) and Blizzard's Diablo II game server. Various custom applications also use this port as a default. It is in the registered port range and frequently appears in network scans due to its use by multiple different services.

TCP/UDP Messaging

Security Considerations

Port 4000 (ICQ / Diablo II) is classified as medium risk. While this service is commonly exposed, consider using encrypted alternatives where available.

Recommendation: Keep the service updated. Monitor logs for unusual activity.

Related Ports — Messaging

18 MSP 87 ttylink / link 98 TACNews 99 Metagram 119 NNTP 169 SEND 194 IRC 218 MPP

Related Terms

ARP FTP HTTP ICMP IMAP NTP