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// Remote access

Port 992: telnet protocol over TLS/SSL

Port 992 is assigned by IANA to telnets (telnet protocol over TLS/SSL).

992

How telnets works

Remote access
terminal:992telnets terminal:992telnets

The client opens a session to port 992: each command typed is sent to the server, which runs it and returns the output. Everything is encrypted: someone on the path only sees unreadable bytes.

Transport
TCP · UDP
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
Remote access
01 Security

Is port 992 dangerous?

We have no specific security note for port 992. 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 992

ServicePortTransportDescriptionReferenceUpdated
telnets 992 TCP, UDP telnet protocol over TLS/SSL - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 992, and is it reachable?

Linux

sudo ss -ltnup 'sport = :992'      # process listening on 992
sudo lsof -nP -i :992

macOS

sudo lsof -nP -i :992

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 992 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 992
netstat -ano | findstr :992

From another machine

nmap -p 992 -sV <host>
sudo nmap -sU -p 992 <host>
nc -zv <host> 992

Block it in the firewall

sudo ufw deny 992/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 992" -Direction Inbound -LocalPort 992 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 992 used for?

Port 992 is assigned by IANA to telnets (telnet protocol over TLS/SSL).

Is port 992 TCP or UDP?

Port 992 is registered for TCP and UDP.

Is it safe to open port 992?

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 992 is open?

On Linux run "ss -ltnup 'sport = :992'", on macOS "lsof -nP -i :992", and on Windows "netstat -ano | findstr :992" to see the local process. From another machine, "nmap -p 992 <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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