CyberHunter
Local dataset, no network
// Other services

Port 1999: cisco identification port

Port 1999 is assigned by IANA to tcp-id-port (cisco identification port).

1999

How tcp-id-port works

Other services
client:1999tcp-id-portresponse client:1999tcp-id-portresponse

The client sends a request to port 1999 and the tcp-id-port 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 1999 dangerous?

We have no specific security note for port 1999. 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 1999

ServicePortTransportDescriptionReferenceUpdated
tcp-id-port 1999 TCP, UDP cisco identification port - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 1999, and is it reachable?

Linux

sudo ss -ltnup 'sport = :1999'      # process listening on 1999
sudo lsof -nP -i :1999

macOS

sudo lsof -nP -i :1999

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 1999 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 1999
netstat -ano | findstr :1999

From another machine

nmap -p 1999 -sV <host>
sudo nmap -sU -p 1999 <host>
nc -zv <host> 1999

Block it in the firewall

sudo ufw deny 1999/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 1999" -Direction Inbound -LocalPort 1999 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 1999 used for?

Port 1999 is assigned by IANA to tcp-id-port (cisco identification port).

Is port 1999 TCP or UDP?

Port 1999 is registered for TCP and UDP.

Is it safe to open port 1999?

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 1999 is open?

On Linux run "ss -ltnup 'sport = :1999'", on macOS "lsof -nP -i :1999", and on Windows "netstat -ano | findstr :1999" to see the local process. From another machine, "nmap -p 1999 <host>" shows whether it is reachable.

05 Related
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