Port 4000Diablo II
TCP/UDP port 4000 is primarily known for facilitating the multiplayer connections of the classic Blizzard game Diablo II. The port allows players to connect to Battle.net servers or direct peer-to-peer sessions, enabling matchmaking, in-game communication, and other gameplay features..
- transport
- tcp · udp
- in transit
- cleartext
- assignment
- unofficial
- risk
- 4/10
- lookups
- 4,310
2 transports registered
payload readable on path
used by convention
caution
rank 976 of 993 · top 98%
Technical Details
what runs on :4000Port 4000 is widely recognized for its association with Blizzard Entertainment's action role-playing game Diablo II. When players initiate multiplayer sessions, either through LAN or via the Battle.net platform, the game communicates using this port. The protocol involves both TCP and UDP traffic to support various game functions—in particular, TCP manages reliable data transfer such as user authentication and game state synchronization, while UDP facilitates fast, low-latency updates critical for responsive gameplay.
Technically, the port handles a custom Blizzard-designed application protocol. This protocol enables session management, player authentication, real-time messaging, and the coordination of game state across multiple participants. Because the protocol is proprietary, detailed packet structure is not publicly documented, but network analysis shows bidirectional exchange of game-critical information throughout the session lifespan.
Besides Diablo II, port 4000 may also be employed by fan-made private servers, community tools, and mods, all adhering broadly to Blizzard's communication style. Occasionally, the port is reused in unrelated gaming setups, but its identity is predominantly tied to Diablo II's multiplayer environment.
Security Information
exposure of :4000risk score
4/ 10caution
worth attention. how exposed you are depends on configuration — don't leave it reachable from the internet without a reason.
gaming averages 4.0 across 124 ports — this one sits level with it.
in transit
cleartext
credentials and payloads are readable by anyone on path
assignment
unofficial
used by convention, not registered — what answers here varies by deployment
reachable over
tcp · udp
udp is connectionless — source addresses are trivially spoofed and it is a reflection favourite
security overview
Common Vulnerabilities:
- Since port 4000 is often left open to facilitate multiplayer gaming, it can serve as an entry point for malicious actors scanning for open ports.
- Use of unofficial servers or unpatched game versions may expose users to exploits like buffer overflows or man-in-the-middle attacks.
- Because the protocol lacks built-in encryption and advanced authentication, sensitive information such as credentials might be susceptible to interception.
Common Mitigations:
- Limit port exposure to trusted IP ranges via firewall rules.
- Employ up-to-date game versions and official servers to reduce the risk of vulnerabilities.
- Use intrusion detection systems to monitor unusual activity on this port.
- Encourage encrypted VPN tunnels for securing all game-related traffic.
- Disable or block port 4000 exposure when Diablo II is not in use.
Related Ports
the 8 most looked-up other ports in gaming — 124 ports carry that label.
| port | service | risk | |||
|---|---|---|---|---|---|
| :8888 | D2GS Admin Console | TCP | Remote Access | caution | 83.7k |
| :8888 | Earthland Realms 2 Server | TCP | Gaming | caution | 73.1k |
| :1513 | Garena Gaming | TCPUDP | Gaming | caution | 33.1k |
| :5555 | Freeciv | TCP | Security | caution | 26.9k |
| :18200 | Audition Online Server Check | TCPUDP | Gaming | caution | 20.9k |
| :12345 | NetBus / NetBuster | Security | caution | 19.9k | |
| :18206 | Audition FAM DB | TCPUDP | Databases | caution | 19.1k |
| :18505 | Audition Dance Battle Status Check | TCPUDP | Network Services | caution | 18.9k |
risk mix of the 8 listed
- caution100%
0 of 8 encrypted