Port 3785Bidirectional Forwarding Detection (BFD) Echo

BFD Echo uses UDP port 3785 to test whether packets can traverse a network forwarding path and return.

transport: tcp · udp
in transit: cleartext
assignment: official
risk: 2/10
lookups: 0

also known as bfd-echo

1 other service is registered on port 3785. compare all 2 →

Technical Details

what runs on :3785

BFD Echo is a forwarding-path liveness function: one system sends UDP echo packets toward its peer, which loops them back through the forwarding plane so the sender can detect loss or delay. The packet format is defined by BFD, and the standard destination port is UDP 3785; BFD control traffic normally uses UDP 3784, while BFD control for multihop paths uses UDP 4784. Although the IANA entry lists TCP as well as UDP, standard BFD Echo operates over UDP, not TCP. This is not typically a conventional application listener: the router or appliance handles packets as part of a configured BFD session.

Security Information

exposure of :3785

risk score

2/ 10safe

routine exposure. this port is rarely the way in on its own — keep it patched and logged and move on.

network services averages 2.7 across 1,451 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

BFD Echo traffic is not encrypted or authenticated, so it should be limited to trusted, configured peers and filtered at network boundaries rather than exposed broadly to the internet. Injected or unwanted traffic can consume resources or interfere with liveness testing; authentication configured for BFD control traffic does not authenticate Echo packets.

Record

iana registry entry

port: :3785
service: Bidirectional Forwarding Detection (BFD) Echo
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 2/10safe
category: Network Services
usage: Routers and network appliances use BFD Echo to check forwarding-path liveness between BFD peers, often alongside BFD control traffic on UDP 3784. It is generally encountered on configured network links rather than as a general-purpose internet-facing service.
lookups: 0rank 993
added: 2026-10-01
updated: 2026-10-01
references: IANA service name registry — port 3785
RFC 5881

Something wrong?

This record is maintained by the engineers who use port 3785. 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 2026-10-01.

01edit any field on a page of its own
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edit this record →back to the registry

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risk mix of the 8 listed

caution100%

0 of 8 encrypted

Port :3785Bidirectional Forwarding Detection (BFD) Echo

Technical Details

Security Information

Related Ports

Port 3785Bidirectional Forwarding Detection (BFD) Echo