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// Databases & caches

Port 17500: Dropbox LanSync Protocol

Port 17500 is assigned by IANA to db-lsp (Dropbox LanSync Protocol), db-lsp-disc (Dropbox LanSync Discovery).

17500

How db-lsp works

Databases & caches
app:17500db-lsp app:17500db-lsp

The application sends a SQL query to the db-lsp server on port 17500, which returns rows from its tables.

Transport
TCP · UDP
Exposure risk
not rated depends on the program listening
Encryption
Unknownnot stated by the registry
IANA status
Assigned2 registered services
Range
Registered (1024-49151)
Category
Databases & caches
01 Security

Is port 17500 dangerous?

We have no specific security note for port 17500. Its risk depends on the program actually listening on it. General advice for databases & caches services:

  • Bind the service to localhost or a private network, never to a public address.
  • Enable authentication, use per-application accounts and require TLS.
  • Watch for exposed Docker ports: publish them on 127.0.0.1 only.
02 Registry

IANA registry entries for port 17500

ServicePortTransportDescriptionReferenceUpdated
db-lsp 17500 TCP Dropbox LanSync Protocol - 2010-01-21
db-lsp-disc 17500 UDP Dropbox LanSync Discovery - 2010-01-21

// source: IANA service name and port number registry

03 Check it

Which program uses port 17500, and is it reachable?

Linux

sudo ss -ltnup 'sport = :17500'      # process listening on 17500
sudo lsof -nP -i :17500

macOS

sudo lsof -nP -i :17500

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 17500 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 17500
netstat -ano | findstr :17500

From another machine

nmap -p 17500 -sV <host>
sudo nmap -sU -p 17500 <host>
nc -zv <host> 17500

Block it in the firewall

sudo ufw deny 17500/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 17500" -Direction Inbound -LocalPort 17500 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 17500 used for?

Port 17500 is assigned by IANA to db-lsp (Dropbox LanSync Protocol), db-lsp-disc (Dropbox LanSync Discovery).

Is port 17500 TCP or UDP?

Port 17500 is registered for TCP and UDP.

Is it safe to open port 17500?

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. Bind the service to localhost or a private network, never to a public address.

How do I check if port 17500 is open?

On Linux run "ss -ltnup 'sport = :17500'", on macOS "lsof -nP -i :17500", and on Windows "netstat -ano | findstr :17500" to see the local process. From another machine, "nmap -p 17500 <host>" shows whether it is reachable.

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