CyberHunter
Local dataset, no network
// Other services

Port 4026: Graphical Debug Server

Port 4026 is assigned by IANA to as-debug (Graphical Debug Server).

4026

How as-debug works

Other services
client:4026as-debugresponse client:4026as-debugresponse

The client sends a request to port 4026 and the as-debug 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 4026 dangerous?

We have no specific security note for port 4026. 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 4026

ServicePortTransportDescriptionReferenceUpdated
as-debug 4026 TCP, UDP Graphical Debug Server - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 4026, and is it reachable?

Linux

sudo ss -ltnup 'sport = :4026'      # process listening on 4026
sudo lsof -nP -i :4026

macOS

sudo lsof -nP -i :4026

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 4026 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 4026
netstat -ano | findstr :4026

From another machine

nmap -p 4026 -sV <host>
sudo nmap -sU -p 4026 <host>
nc -zv <host> 4026

Block it in the firewall

sudo ufw deny 4026/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 4026" -Direction Inbound -LocalPort 4026 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 4026 used for?

Port 4026 is assigned by IANA to as-debug (Graphical Debug Server).

Is port 4026 TCP or UDP?

Port 4026 is registered for TCP and UDP.

Is it safe to open port 4026?

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 4026 is open?

On Linux run "ss -ltnup 'sport = :4026'", on macOS "lsof -nP -i :4026", and on Windows "netstat -ano | findstr :4026" to see the local process. From another machine, "nmap -p 4026 <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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