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Port 6124 (pnbs)

IANA assigns port 6124 to pnbs: Phlexible Network Backup Service.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
pnbs TCP Phlexible Network Backup Service William R Lear 2 -
pnbs UDP Phlexible Network Backup Service William R Lear 2 -

Registry dates for this port: registered 2008-10-23.

Check what is listening on port 6124

Linux: is anything listening on TCP 6124?
sudo ss -tlnp 'sport = :6124'
Linux: UDP 6124
sudo ss -ulnp 'sport = :6124'
Linux / macOS: which process owns the port
sudo lsof -nP -i :6124
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':6124 '
Windows (Command Prompt)
netstat -ano | findstr :6124
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 6124 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 6124
From Windows
Test-NetConnection HOST -Port 6124
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 6124

Block port 6124 in the firewall

ufw
sudo ufw deny 6124/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 6124 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 6124 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 6124' -Direction Inbound -Protocol TCP -LocalPort 6124 -Action Block
ufw
sudo ufw deny 6124/udp
iptables
sudo iptables -A INPUT -p udp --dport 6124 -j DROP
nftables
sudo nft add rule inet filter input udp dport 6124 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 6124' -Direction Inbound -Protocol UDP -LocalPort 6124 -Action Block

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Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.