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// Other services

Port 6403: boe-cachesvr

Port 6403 is assigned by IANA to boe-cachesvr (boe-cachesvr).

6403

How boe-cachesvr works

Other services
client:6403boe-cachesvrresponse client:6403boe-cachesvrresponse

The client sends a request to port 6403 and the boe-cachesvr service answers.

Transport
None registered
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 6403 dangerous?

We have no specific security note for port 6403. 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 6403

ServicePortTransportDescriptionReferenceUpdated
boe-cachesvr 6403 - boe-cachesvr - 2026-05-27

// source: IANA service name and port number registry

03 Check it

Which program uses port 6403, and is it reachable?

Linux

sudo ss -ltnup 'sport = :6403'      # process listening on 6403
sudo lsof -nP -i :6403

macOS

sudo lsof -nP -i :6403

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 6403 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 6403
netstat -ano | findstr :6403

From another machine

nmap -p 6403 -sV <host>
nc -zv <host> 6403

Block it in the firewall

sudo ufw deny 6403/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 6403" -Direction Inbound -LocalPort 6403 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 6403 used for?

Port 6403 is assigned by IANA to boe-cachesvr (boe-cachesvr).

Is port 6403 TCP or UDP?

Port 6403 has no registered transport. Any program can still use it over TCP or UDP.

Is it safe to open port 6403?

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 6403 is open?

On Linux run "ss -ltnup 'sport = :6403'", on macOS "lsof -nP -i :6403", and on Windows "netstat -ano | findstr :6403" to see the local process. From another machine, "nmap -p 6403 <host>" shows whether it is reachable.

05 Related
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