Port 4691Monotone Netsync Protocol

Monotone distributed version-control repository synchronization service.

transport: tcp · udp
in transit: cleartext
assignment: official
risk: 3/10
lookups: 0

also known as mtn, Monotone sync

Technical Details

what runs on :4691

Monotone Netsync is the repository synchronization protocol used by the mtn client and server. A connection negotiates a Netsync session, authenticates the participating Monotone identities, and exchanges repository data such as revisions, manifests, keys, and file content. The standard service port is TCP 4691; Monotone can also be operated through SSH or other tunnels, and the IANA assignment includes UDP even though normal Netsync operation is TCP-based.

Security Information

exposure of :4691

risk score

3/ 10caution

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

network services averages 3.7 across 661 ports — this one sits 0.7 below.

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

This service should generally be restricted to trusted repository peers rather than exposed broadly to the Internet. Authentication and Monotone's signed repository objects help protect repository integrity, but an exposed service can disclose repository metadata or content to authorized peers and can be targeted for connection or resource exhaustion; encryption should be provided by an appropriate tunnel when confidentiality is required.

Record

iana registry entry

port: :4691
service: Monotone Netsync Protocol
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 3/10caution
category: Network Services System
usage: Port 4691 is used by Monotone, a distributed version-control system, for Netsync synchronization between repositories and clients. Monotone normally uses TCP for repository synchronization; the assignment is registered to Thomas Keller for both TCP and UDP, although UDP deployments are uncommon.
lookups: 0rank 994
added: 2026-08-22
updated: 2026-08-22
references: IANA service name registry — port 4691

Something wrong?

This record is maintained by the engineers who use port 4691. Every field on it is editable — change what's wrong, say how you know, and a reviewer publishes it, usually within a minute. Last touched 2026-08-22.

01edit any field on a page of its own
02a model checks it for accuracy and spam
03clean and confident goes live immediately

edit this record →back to the registry

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risk mix of the 8 listed

caution100%

0 of 8 encrypted

Port :4691Monotone Netsync Protocol

Technical Details

Security Information

Related Ports

Port 4691Monotone Netsync Protocol