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// Other services

Port 3103: Autocue SMI Protocol

Port 3103 is assigned by IANA to autocuesmi (Autocue SMI Protocol).

3103

How autocuesmi works

Other services
client:3103autocuesmiresponse client:3103autocuesmiresponse

The client sends a request to port 3103 and the autocuesmi service answers.

Transport
TCP · UDP
Exposure risk
not rated depends on the program listening
Encryption
Unknownnot stated by the registry
IANA status
Assigned1 registered service
Range
Registered (1024-49151)
Category
Other services
01 Security

Is port 3103 dangerous?

We have no specific security note for port 3103. Its risk depends on the program actually listening on it. General advice for other services services:

  • Close the port if nothing on the host needs it.
  • Identify the process that listens on it (commands below) before opening it in a firewall.
  • Expose a service only to the networks that use it.
02 Registry

IANA registry entries for port 3103

ServicePortTransportDescriptionReferenceUpdated
autocuesmi 3103 TCP, UDP Autocue SMI Protocol - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 3103, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3103'      # process listening on 3103
sudo lsof -nP -i :3103

macOS

sudo lsof -nP -i :3103

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3103 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3103
netstat -ano | findstr :3103

From another machine

nmap -p 3103 -sV <host>
sudo nmap -sU -p 3103 <host>
nc -zv <host> 3103

Block it in the firewall

sudo ufw deny 3103/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3103" -Direction Inbound -LocalPort 3103 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3103 used for?

Port 3103 is assigned by IANA to autocuesmi (Autocue SMI Protocol).

Is port 3103 TCP or UDP?

Port 3103 is registered for TCP and UDP.

Is it safe to open port 3103?

It depends on the program that listens on it. Open it only for a service you know and only to the networks that need it. Close the port if nothing on the host needs it.

How do I check if port 3103 is open?

On Linux run "ss -ltnup 'sport = :3103'", on macOS "lsof -nP -i :3103", and on Windows "netstat -ano | findstr :3103" to see the local process. From another machine, "nmap -p 3103 <host>" shows whether it is reachable.

05 Related
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