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// Network services

Port 11171: Surgical Notes Security Service Discovery (SNSS)

Port 11171 is assigned by IANA to snss (Surgical Notes Security Service Discovery (SNSS)).

11171

How snss works

Network services
client:11171snssresponse client:11171snssresponse

The client sends a request to port 11171 and the snss service answers.

Transport
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
Network services
01 Security

Is port 11171 dangerous?

We have no specific security note for port 11171. Its risk depends on the program actually listening on it. General advice for network services services:

  • Answer only the networks that need the service (no open resolvers, relays or reflectors).
  • UDP services can be abused for DDoS amplification: rate-limit or block them at the edge.
  • Disable legacy test services that have no use in production.
02 Registry

IANA registry entries for port 11171

ServicePortTransportDescriptionReferenceUpdated
snss 11171 UDP Surgical Notes Security Service Discovery (SNSS) - 2010-12-24
-11171-Reserved--

// source: IANA service name and port number registry

03 Check it

Which program uses port 11171, and is it reachable?

Linux

sudo ss -ltnup 'sport = :11171'      # process listening on 11171
sudo lsof -nP -i :11171

macOS

sudo lsof -nP -i :11171

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 11171 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 11171
netstat -ano | findstr :11171

From another machine

nmap -p 11171 -sV <host>
sudo nmap -sU -p 11171 <host>
nc -zv <host> 11171

Block it in the firewall

sudo ufw deny 11171/udp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 11171" -Direction Inbound -LocalPort 11171 -Protocol UDP -Action Block  # Windows
04 FAQ
What is port 11171 used for?

Port 11171 is assigned by IANA to snss (Surgical Notes Security Service Discovery (SNSS)).

Is port 11171 TCP or UDP?

Port 11171 is registered for UDP.

Is it safe to open port 11171?

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. Answer only the networks that need the service (no open resolvers, relays or reflectors).

How do I check if port 11171 is open?

On Linux run "ss -ltnup 'sport = :11171'", on macOS "lsof -nP -i :11171", and on Windows "netstat -ano | findstr :11171" to see the local process. From another machine, "nmap -p 11171 <host>" shows whether it is reachable.

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