CyberHunter
Local dataset, no network
// File transfer & sharing

Port 18243: Checkpoint router state backup

Port 18243 is assigned by IANA to clusterxl (Checkpoint router state backup).

18243

How clusterxl works

File transfer & sharing
client:182431/32/33/3clusterxl client:182431/32/33/3clusterxl

Files are sent over port 18243 in pieces and reassembled on the other side.

Transport
TCP
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
File transfer & sharing
01 Security

Is port 18243 dangerous?

We have no specific security note for port 18243. Its risk depends on the program actually listening on it. General advice for file transfer & sharing services:

  • Prefer encrypted protocols (SFTP, FTPS, SMB 3 with encryption).
  • Disable anonymous access and restrict shares or exports to known hosts.
  • Never publish file sharing protocols to the Internet.
02 Registry

IANA registry entries for port 18243

ServicePortTransportDescriptionReferenceUpdated
clusterxl 18243 TCP Checkpoint router state backup - 2012-06-28
-18243-Reserved--

// source: IANA service name and port number registry

03 Check it

Which program uses port 18243, and is it reachable?

Linux

sudo ss -ltnup 'sport = :18243'      # process listening on 18243
sudo lsof -nP -i :18243

macOS

sudo lsof -nP -i :18243

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 18243 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 18243
netstat -ano | findstr :18243

From another machine

nmap -p 18243 -sV <host>
nc -zv <host> 18243

Block it in the firewall

sudo ufw deny 18243/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 18243" -Direction Inbound -LocalPort 18243 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 18243 used for?

Port 18243 is assigned by IANA to clusterxl (Checkpoint router state backup).

Is port 18243 TCP or UDP?

Port 18243 is registered for TCP.

Is it safe to open port 18243?

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. Prefer encrypted protocols (SFTP, FTPS, SMB 3 with encryption).

How do I check if port 18243 is open?

On Linux run "ss -ltnup 'sport = :18243'", on macOS "lsof -nP -i :18243", and on Windows "netstat -ano | findstr :18243" to see the local process. From another machine, "nmap -p 18243 <host>" shows whether it is reachable.

05 Related
:445 SMB tcp · udp · critical risk :21 FTP tcp · udp · sctp · high risk :139 NetBIOS Session tcp · udp · high risk :69 TFTP udp · tcp · high risk :2049 NFS tcp · udp · sctp · high risk :873 rsync tcp · udp · high risk :20 File Transfer [Default Data] tcp · udp · sctp :115 Simple File Transfer Protocol tcp · udp

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