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Port 3257 (cpqrpm-server)

IANA assigns port 3257 to cpqrpm-server: Compaq RPM Server Port.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
cpqrpm-server TCP Compaq RPM Server Port Royal King -
cpqrpm-server UDP Compaq RPM Server Port Royal King -

Registry dates for this port: registered 2002-02.

Check what is listening on port 3257

Linux: is anything listening on TCP 3257?
sudo ss -tlnp 'sport = :3257'
Linux: UDP 3257
sudo ss -ulnp 'sport = :3257'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3257
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3257 '
Windows (Command Prompt)
netstat -ano | findstr :3257
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3257 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3257
From Windows
Test-NetConnection HOST -Port 3257
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3257

Block port 3257 in the firewall

ufw
sudo ufw deny 3257/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3257 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3257 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3257' -Direction Inbound -Protocol TCP -LocalPort 3257 -Action Block
ufw
sudo ufw deny 3257/udp
iptables
sudo iptables -A INPUT -p udp --dport 3257 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3257 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3257' -Direction Inbound -Protocol UDP -LocalPort 3257 -Action Block

Related ports

3255semaphore3256cpqrpm-agent3258ivecon-port3259epncdp2

All port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.