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Port 17500 (db-lsp, db-lsp-disc)

IANA assigns port 17500 to db-lsp, db-lsp-disc: Dropbox LanSync Protocol.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
db-lsp TCP Dropbox LanSync Protocol Paul Bohm -
db-lsp-disc UDP Dropbox LanSync Discovery Paul Bohm -

Registry dates for this port: registered 2010-01-21.

Check what is listening on port 17500

Linux: is anything listening on TCP 17500?
sudo ss -tlnp 'sport = :17500'
Linux: UDP 17500
sudo ss -ulnp 'sport = :17500'
Linux / macOS: which process owns the port
sudo lsof -nP -i :17500
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':17500 '
Windows (Command Prompt)
netstat -ano | findstr :17500
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 17500 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 17500
From Windows
Test-NetConnection HOST -Port 17500
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 17500

Block port 17500 in the firewall

ufw
sudo ufw deny 17500/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 17500 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 17500 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 17500' -Direction Inbound -Protocol TCP -LocalPort 17500 -Action Block
ufw
sudo ufw deny 17500/udp
iptables
sudo iptables -A INPUT -p udp --dport 17500 -j DROP
nftables
sudo nft add rule inet filter input udp dport 17500 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 17500' -Direction Inbound -Protocol UDP -LocalPort 17500 -Action Block

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