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Port 170 (print-srv)

IANA assigns port 170 to print-srv: Network PostScript.

Well-known (system) port, 0-1023 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
print-srv TCP Network PostScript Brian Reid -
print-srv UDP Network PostScript Brian Reid -

Check what is listening on port 170

Linux: is anything listening on TCP 170?
sudo ss -tlnp 'sport = :170'
Linux: UDP 170
sudo ss -ulnp 'sport = :170'
Linux / macOS: which process owns the port
sudo lsof -nP -i :170
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':170 '
Windows (Command Prompt)
netstat -ano | findstr :170
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 170 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 170
From Windows
Test-NetConnection HOST -Port 170
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 170

Block port 170 in the firewall

ufw
sudo ufw deny 170/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 170 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 170 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 170' -Direction Inbound -Protocol TCP -LocalPort 170 -Action Block
ufw
sudo ufw deny 170/udp
iptables
sudo iptables -A INPUT -p udp --dport 170 -j DROP
nftables
sudo nft add rule inet filter input udp dport 170 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 170' -Direction Inbound -Protocol UDP -LocalPort 170 -Action Block

Related ports

168rsvd169send171multiplex172cl-1, cl/1

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