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// Network services

Port 6657: PalCom Discovery

Port 6657 is assigned by IANA to palcom-disc (PalCom Discovery).

6657

How palcom-disc works

Network services
client:6657palcom-discresponse client:6657palcom-discresponse

The client sends a request to port 6657 and the palcom-disc service answers.

Transport
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
Network services
01 Security

Is port 6657 dangerous?

We have no specific security note for port 6657. Its risk depends on the program actually listening on it. General advice for network services services:

  • Answer only the networks that need the service (no open resolvers, relays or reflectors).
  • UDP services can be abused for DDoS amplification: rate-limit or block them at the edge.
  • Disable legacy test services that have no use in production.
02 Registry

IANA registry entries for port 6657

ServicePortTransportDescriptionReferenceUpdated
palcom-disc 6657 UDP PalCom Discovery - 2010-12-06
-6657-Reserved--

// source: IANA service name and port number registry

03 Check it

Which program uses port 6657, and is it reachable?

Linux

sudo ss -ltnup 'sport = :6657'      # process listening on 6657
sudo lsof -nP -i :6657

macOS

sudo lsof -nP -i :6657

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 6657 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 6657
netstat -ano | findstr :6657

From another machine

nmap -p 6657 -sV <host>
sudo nmap -sU -p 6657 <host>
nc -zv <host> 6657

Block it in the firewall

sudo ufw deny 6657/udp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 6657" -Direction Inbound -LocalPort 6657 -Protocol UDP -Action Block  # Windows
04 FAQ
What is port 6657 used for?

Port 6657 is assigned by IANA to palcom-disc (PalCom Discovery).

Is port 6657 TCP or UDP?

Port 6657 is registered for UDP.

Is it safe to open port 6657?

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. Answer only the networks that need the service (no open resolvers, relays or reflectors).

How do I check if port 6657 is open?

On Linux run "ss -ltnup 'sport = :6657'", on macOS "lsof -nP -i :6657", and on Windows "netstat -ano | findstr :6657" to see the local process. From another machine, "nmap -p 6657 <host>" shows whether it is reachable.

05 Related
:53 DNS tcp · udp · moderate risk :135 MS RPC tcp · udp · high risk :123 NTP udp · tcp · moderate risk :67 DHCP server udp · tcp · moderate risk :111 rpcbind tcp · udp · high risk :9100 Raw printing (JetDirect) tcp · udp · high risk :631 IPP / CUPS tcp · udp · high risk :5353 mDNS udp · tcp · moderate risk

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