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// Remote access

Port 3696: Telnet Com Port Control

Port 3696 is assigned by IANA to telnetcpcd (Telnet Com Port Control).

3696

How telnetcpcd works

Remote access
terminal:3696telnetcpcd terminal:3696telnetcpcd

The client opens a session to port 3696: each command typed is sent to the server, which runs it and returns the output.

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
Remote access
01 Security

Is port 3696 dangerous?

We have no specific security note for port 3696. Its risk depends on the program actually listening on it. General advice for remote access services:

  • Do not expose remote administration directly: use a VPN or a zero-trust access proxy.
  • Require MFA or key-based authentication and lock out brute-force attempts.
  • Log every login and alert on new source addresses.
02 Registry

IANA registry entries for port 3696

ServicePortTransportDescriptionReferenceUpdated
telnetcpcd 3696 TCP, UDP Telnet Com Port Control - 2003-02

// source: IANA service name and port number registry

03 Check it

Which program uses port 3696, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3696'      # process listening on 3696
sudo lsof -nP -i :3696

macOS

sudo lsof -nP -i :3696

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3696 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3696
netstat -ano | findstr :3696

From another machine

nmap -p 3696 -sV <host>
sudo nmap -sU -p 3696 <host>
nc -zv <host> 3696

Block it in the firewall

sudo ufw deny 3696/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3696" -Direction Inbound -LocalPort 3696 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3696 used for?

Port 3696 is assigned by IANA to telnetcpcd (Telnet Com Port Control).

Is port 3696 TCP or UDP?

Port 3696 is registered for TCP and UDP.

Is it safe to open port 3696?

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. Do not expose remote administration directly: use a VPN or a zero-trust access proxy.

How do I check if port 3696 is open?

On Linux run "ss -ltnup 'sport = :3696'", on macOS "lsof -nP -i :3696", and on Windows "netstat -ano | findstr :3696" to see the local process. From another machine, "nmap -p 3696 <host>" shows whether it is reachable.

05 Related
:22 SSH tcp · udp · sctp · moderate risk :3389 RDP tcp · udp · critical risk :23 Telnet tcp · udp · critical risk :5900 VNC tcp · udp · critical risk :5985 WinRM (HTTP) tcp · udp · high risk :5986 WinRM (HTTPS) tcp · udp · high risk :10000 Webmin tcp · udp · high risk :89 SU/MIT Telnet Gateway tcp · udp

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