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Port 5309 (jprinter)

IANA assigns port 5309 to jprinter: J Printer.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
jprinter TCP J Printer Ken Blackwell -
jprinter UDP J Printer Ken Blackwell -

Check what is listening on port 5309

Linux: is anything listening on TCP 5309?
sudo ss -tlnp 'sport = :5309'
Linux: UDP 5309
sudo ss -ulnp 'sport = :5309'
Linux / macOS: which process owns the port
sudo lsof -nP -i :5309
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':5309 '
Windows (Command Prompt)
netstat -ano | findstr :5309
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 5309 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 5309
From Windows
Test-NetConnection HOST -Port 5309
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 5309

Block port 5309 in the firewall

ufw
sudo ufw deny 5309/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 5309 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 5309 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 5309' -Direction Inbound -Protocol TCP -LocalPort 5309 -Action Block
ufw
sudo ufw deny 5309/udp
iptables
sudo iptables -A INPUT -p udp --dport 5309 -j DROP
nftables
sudo nft add rule inet filter input udp dport 5309 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 5309' -Direction Inbound -Protocol UDP -LocalPort 5309 -Action Block

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