Port 5500Hotline / VNC reverse-connection listener

Historically used by Hotline servers and by VNC viewers awaiting reverse RFB connections; neither use is implied by the IANA assignment.

inFile Transfer Remote Access

transport: tcp · udp
in transit: cleartext
assignment: official
risk: 6/10
lookups: 0

also known as fcp-addr-srvr1, VNC reverse connection, RFB

1 other service is registered on port 5500. compare all 2 →

Technical Details

what runs on :5500

The registered service name is fcp-addr-srvr1, but the best-known uses of TCP 5500 are unrelated. Hotline clients traditionally connect to servers on TCP 5500 using Hotline's proprietary protocol. VNC viewers in listen mode commonly accept server-initiated callbacks on TCP 5500; the RFB connection begins with a version exchange followed by security-type negotiation. Ordinary VNC connections instead typically use TCP 5900 plus the display number. The registry also lists UDP, but these common Hotline and VNC uses are TCP-based; an open UDP port cannot be identified from the assignment alone.

Security Information

exposure of :5500

risk score

6/ 10risk

treat as sensitive. widely scanned and regularly exploited when reachable — restrict it to known sources.

file transfer averages 3.4 across 186 ports — this one sits 2.6 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

Do not expose an unexpected listener without identifying it. A VNC callback listener can lead to desktop access depending on the negotiated security and viewer configuration; RFB does not encrypt the desktop stream by default, and some configurations permit no authentication. Hotline is a legacy service, so its access controls and any encryption depend on the implementation. Restrict access to trusted networks and use a secure tunnel where needed.

Record

iana registry entry

port: :5500
service: Hotline / VNC reverse-connection listener
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 6/10risk
category: File Transfer Remote Access
usage: IANA assigns TCP and UDP 5500 as `fcp-addr-srvr1` to Ken Wittmer. In practice, TCP 5500 is also a historic default for Hotline servers and a listen port for VNC viewers receiving reverse connections from VNC servers.
lookups: 0rank 993
added: 2026-10-08
updated: 2026-10-08
references: IANA service name registry — port 5500

Something wrong?

This record is maintained by the engineers who use port 5500. 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 2026-10-08.

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edit this record →back to the registry

Related Ports

all 186 in file transfer →

the 8 most looked-up other ports in file transfer — 186 ports carry that label.

port	service	proto	category	risk	views
:9080	Groove RPC	TCPUDP	Web Services	caution	70.8k
:17500	Dropbox LAN Sync	TCPUDP	File Transfer	caution	43.7k
:548	Apple Filing Protocol	TCP	File Transfer	caution	36.8k
:7000	Vuze HTTPS Tracker	TCPtls	Security	caution	28.9k
:1337	PowerFolder P2P	TCP	Security	caution	27.1k
:9001	SharePoint Authoring		Web Services	caution	26.3k
:8080	FilePhile Relay	UDP	File Transfer	caution	25.6k
:1337	WASTE Encrypted Sharing	TCP	Security	caution	22.9k

risk mix of the 8 listed

caution100%

1 of 8 encrypted

Port :5500Hotline / VNC reverse-connection listener

Technical Details

Security Information

Related Ports

Port 5500Hotline / VNC reverse-connection listener