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// File transfer & sharing

Port 6124: Phlexible Network Backup Service

Port 6124 is assigned by IANA to pnbs (Phlexible Network Backup Service).

6124

How pnbs works

File transfer & sharing
client:61241/32/33/3pnbs client:61241/32/33/3pnbs

Files are sent over port 6124 in pieces and reassembled on the other side.

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
File transfer & sharing
01 Security

Is port 6124 dangerous?

We have no specific security note for port 6124. 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 6124

ServicePortTransportDescriptionReferenceUpdated
pnbs 6124 TCP, UDP Phlexible Network Backup Service - 2008-10-23

// source: IANA service name and port number registry

03 Check it

Which program uses port 6124, and is it reachable?

Linux

sudo ss -ltnup 'sport = :6124'      # process listening on 6124
sudo lsof -nP -i :6124

macOS

sudo lsof -nP -i :6124

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 6124 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 6124
netstat -ano | findstr :6124

From another machine

nmap -p 6124 -sV <host>
sudo nmap -sU -p 6124 <host>
nc -zv <host> 6124

Block it in the firewall

sudo ufw deny 6124/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 6124" -Direction Inbound -LocalPort 6124 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 6124 used for?

Port 6124 is assigned by IANA to pnbs (Phlexible Network Backup Service).

Is port 6124 TCP or UDP?

Port 6124 is registered for TCP and UDP.

Is it safe to open port 6124?

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 6124 is open?

On Linux run "ss -ltnup 'sport = :6124'", on macOS "lsof -nP -i :6124", and on Windows "netstat -ano | findstr :6124" to see the local process. From another machine, "nmap -p 6124 <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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