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// Other services

Port 271: IETF Network Endpoint Assessment (NEA) Posture Transport Protocol over TLS (PT-TLS)

Port 271 is assigned by IANA to pt-tls (IETF Network Endpoint Assessment (NEA) Posture Transport Protocol over TLS (PT-TLS)).

271

How pt-tls works

Other services
client:271#%&@!x9response? client:271#%&@!x9response?

The client sends a request to port 271 and the pt-tls service answers. Everything is encrypted: someone on the path only sees unreadable bytes.

Transport
TCP
Exposure risk
not rated depends on the program listening
Encryption
EncryptedTLS or built-in crypto
IANA status
Assigned1 registered service
Range
Well-known (0-1023)
Category
Other services
01 Security

Is port 271 dangerous?

We have no specific security note for port 271. 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 271

ServicePortTransportDescriptionReferenceUpdated
pt-tls 271 TCP IETF Network Endpoint Assessment (NEA) Posture Transport Protocol over TLS (PT-TLS) RFC 6876 2012-07-31
-271-Reserved--

// source: IANA service name and port number registry

03 Check it

Which program uses port 271, and is it reachable?

Linux

sudo ss -ltnup 'sport = :271'      # process listening on 271
sudo lsof -nP -i :271

macOS

sudo lsof -nP -i :271

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 271 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 271
netstat -ano | findstr :271

From another machine

nmap -p 271 -sV <host>
nc -zv <host> 271

Block it in the firewall

sudo ufw deny 271/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 271" -Direction Inbound -LocalPort 271 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 271 used for?

Port 271 is assigned by IANA to pt-tls (IETF Network Endpoint Assessment (NEA) Posture Transport Protocol over TLS (PT-TLS)).

Is port 271 TCP or UDP?

Port 271 is registered for TCP.

Is it safe to open port 271?

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 271 is open?

On Linux run "ss -ltnup 'sport = :271'", on macOS "lsof -nP -i :271", and on Windows "netstat -ano | findstr :271" to see the local process. From another machine, "nmap -p 271 <host>" shows whether it is reachable.

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