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Port 6901Windows Live Messenger Voice

Port 6901 was commonly used by Windows Live Messenger for its voice chat functionality, enabling users to engage in real-time audio conversations alongside instant messaging. This port facilitated media streaming required for voice communication, relying on both TCP and UDP protocols for establishing connections and managing data transfer. Although the service is largely obsolete today, the port still highlights legacy voice-over-IP communication support within consumer instant messaging clients..

inStreamingVoice and Chat
transport
tcp · udp

2 transports registered

in transit
cleartext

payload readable on path

assignment
unofficial

used by convention

risk
4/10

caution

lookups
6,034

rank 825 of 993 · top 83%

1 other service is registered on port 6901. compare all 2 →

Technical Details

what runs on :6901

Port 6901 was historically utilized by Microsoft’s Windows Live Messenger application, specifically for enabling voice chat features. The port allowed peer-to-peer communication streams to be established between Messenger clients, supporting the transmission of audio data necessary for VoIP calls. It operated over both TCP and UDP protocols to manage connection establishment, session maintenance, and data flow depending upon network conditions.

The TCP protocol on port 6901 was generally used to manage signaling and session control messages needed to initiate and terminate voice calls. Meanwhile, the UDP protocol facilitated the actual streaming of real-time audio data, benefiting from lower latency and tolerating occasional data loss inherent in live communication tasks.

With the discontinuation of Windows Live Messenger, port 6901’s specific usage waned. However, understanding its technical role provides insight into early voice chat implementations in IM clients, employing a combination of transport protocols to balance reliability and performance in real-time communications scenarios.

Security Information

exposure of :6901

risk score

4/ 10caution

worth attention. how exposed you are depends on configuration — don't leave it reachable from the internet without a reason.

streaming averages 3.6 across 30 ports — this one sits 0.4 above.

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 historically associated with port 6901 included:

  • Unauthenticated access: Weak authentication could have allowed unauthorized users to intercept or join ongoing voice sessions.
  • Packet sniffing: Lack of encryption exposed voice traffic to network sniffing and potential eavesdropping.
  • Exploitation: Vulnerabilities in the Windows Live Messenger client could allow attackers to cultivate buffer overflows or remote code execution.

Mitigations include:

  • Network controls: Blocking or restricting port 6901 inbound and outbound traffic if Windows Live Messenger functionality is no longer required.
  • Encryption: Employing VPNs or transport encryption layers to prevent interception of voice traffic.
  • Client hardening: Ensuring clients are decommissioned or updated to more secure platforms, and disabling unnecessary legacy services to reduce attack surface.

Related Ports

all 30 in streaming →

the 8 most looked-up other ports in streaming — 30 ports carry that label.

portservicerisk
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:5001Slingboxcaution
:1220QTSS Adminsafe
:19294Google Talk Voice/Videocaution
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:9000SqueezeCentercaution

risk mix of the 8 listed

  • safe13%
  • caution88%

0 of 8 encrypted