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Port 3910 (prnrequest)

IANA assigns port 3910 to prnrequest: Printer Request Port.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
prnrequest TCP Printer Request Port Brett Green -
prnrequest UDP Printer Request Port Brett Green -

Registry dates for this port: registered 2003-11.

Check what is listening on port 3910

Linux: is anything listening on TCP 3910?
sudo ss -tlnp 'sport = :3910'
Linux: UDP 3910
sudo ss -ulnp 'sport = :3910'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3910
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3910 '
Windows (Command Prompt)
netstat -ano | findstr :3910
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3910 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3910
From Windows
Test-NetConnection HOST -Port 3910
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3910

Block port 3910 in the firewall

ufw
sudo ufw deny 3910/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3910 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3910 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3910' -Direction Inbound -Protocol TCP -LocalPort 3910 -Action Block
ufw
sudo ufw deny 3910/udp
iptables
sudo iptables -A INPUT -p udp --dport 3910 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3910 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3910' -Direction Inbound -Protocol UDP -LocalPort 3910 -Action Block

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