Port 639MSDP

The Multicast Source Discovery Protocol (MSDP) is used in inter-domain multicast routing to facilitate the sharing of multicast source information between different multicast-enabled routing domains. It enables routers to discover active multicast sources outside their own domain, enhancing the distribution of multicast streams across the internet..

transport
tcp · udp

2 transports registered

in transit
cleartext

payload readable on path

assignment
official

registered with iana

risk
4/10

caution

lookups
11,356

rank 364 of 993 · top 37%

Technical Details

what runs on :639

The Multicast Source Discovery Protocol (MSDP) operates between multicast-enabled routers to facilitate the exchange of information regarding active multicast sources. It is primarily implemented in conjunction with Protocol Independent Multicast Sparse Mode (PIM-SM) to enable inter-domain multicast routing. By sharing source information, MSDP allows receivers in different PIM-SM domains to join multicast streams initiated in external domains.

MSDP routers establish TCP peer connections, known as MSDP peers, where they exchange Source-Active (SA) messages encapsulating information about multicast sources currently transmitting traffic. These SA messages enable the receiving routers to update their multicast routing tables and forward join messages efficiently to multicast sources, enabling seamless multicast data flow across multiple administrative boundaries.

Despite its effectiveness, MSDP is often considered complex and legacy, especially with newer protocols like Source-Specific Multicast (SSM) simplifying multicast deployments. Nonetheless, MSDP remains in use within protocols where Any-Source Multicast (ASM) operation is required, especially in larger or legacy networks requiring multicast inter-domain communication.

Security Information

exposure of :639

risk score

4/ 10caution

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

network services averages 3.9 across 604 ports — this one sits 0.1 above.

in transit

cleartext

credentials and payloads are readable by anyone on path

assignment

official

registered with iana for this service — scanners fingerprint it by number

reachable over

tcp · udp

udp is connectionless — source addresses are trivially spoofed and it is a reflection favourite

security overview

Common vulnerabilities associated with MSDP include:

  • Misconfiguration leading to unwanted multicast traffic or routing information leaks.
  • Unauthorized access from untrusted peers potentially injecting false multicast source data, leading to multicast routing disruptions or denial-of-service.
  • TCP session hijacking or spoofing which can manipulate SA message exchange.

Mitigation strategies include:

  • Implement strong authentication such as TCP MD5 signatures for MSDP peer connections.
  • Apply strict access control lists (ACLs) to restrict peering only to trusted partner routers.
  • Utilize filtering policies for SA messages to prevent unwanted multicast sources from propagating.
  • Harden network devices by disabling unneeded multicast capabilities where not used, and maintaining up-to-date router software to address known vulnerabilities.

the 8 most looked-up other ports in network services — 604 ports carry that label.

risk mix of the 8 listed

  • caution100%

0 of 8 encrypted