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// Other services

Port 2176: Microsoft ActiveSync Remote API

Port 2176 is assigned by IANA to rapi (Microsoft ActiveSync Remote API).

2176

How rapi works

Other services
client:2176rapiresponse client:2176rapiresponse

The client sends a request to port 2176 and the rapi 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 2176 dangerous?

We have no specific security note for port 2176. 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 2176

ServicePortTransportDescriptionReferenceUpdated
rapi 2176 TCP, UDP Microsoft ActiveSync Remote API - 2005-08

// source: IANA service name and port number registry

03 Check it

Which program uses port 2176, and is it reachable?

Linux

sudo ss -ltnup 'sport = :2176'      # process listening on 2176
sudo lsof -nP -i :2176

macOS

sudo lsof -nP -i :2176

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 2176 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 2176
netstat -ano | findstr :2176

From another machine

nmap -p 2176 -sV <host>
sudo nmap -sU -p 2176 <host>
nc -zv <host> 2176

Block it in the firewall

sudo ufw deny 2176/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 2176" -Direction Inbound -LocalPort 2176 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 2176 used for?

Port 2176 is assigned by IANA to rapi (Microsoft ActiveSync Remote API).

Is port 2176 TCP or UDP?

Port 2176 is registered for TCP and UDP.

Is it safe to open port 2176?

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 2176 is open?

On Linux run "ss -ltnup 'sport = :2176'", on macOS "lsof -nP -i :2176", and on Windows "netstat -ano | findstr :2176" to see the local process. From another machine, "nmap -p 2176 <host>" shows whether it is reachable.

05 Related
:4444 Metasploit default / krb524 tcp · udp · high risk :31337 Back Orifice / elite tcp · udp · high risk :1 TCP Port Service Multiplexer tcp · udp :5 Remote Job Entry tcp · udp :9 Discard tcp · udp · sctp · dccp :11 Active Users tcp · udp :17 Quote of the Day tcp · udp :18 Message Send Protocol (historic) tcp · udp

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