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// Network services

Port 170: Network PostScript

Port 170 is assigned by IANA to print-srv (Network PostScript).

170

How print-srv works

Network services
client:170print-srvresponse client:170print-srvresponse

The client sends a request to port 170 and the print-srv service answers.

Transport
TCP · UDP
Exposure risk
not rated depends on the program listening
Encryption
Unknownnot stated by the registry
IANA status
Assigned1 registered service
Range
Well-known (0-1023)
Category
Network services
01 Security

Is port 170 dangerous?

We have no specific security note for port 170. Its risk depends on the program actually listening on it. General advice for network services services:

  • Answer only the networks that need the service (no open resolvers, relays or reflectors).
  • UDP services can be abused for DDoS amplification: rate-limit or block them at the edge.
  • Disable legacy test services that have no use in production.
02 Registry

IANA registry entries for port 170

ServicePortTransportDescriptionReferenceUpdated
print-srv 170 TCP, UDP Network PostScript - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 170, and is it reachable?

Linux

sudo ss -ltnup 'sport = :170'      # process listening on 170
sudo lsof -nP -i :170

macOS

sudo lsof -nP -i :170

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 170 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 170
netstat -ano | findstr :170

From another machine

nmap -p 170 -sV <host>
sudo nmap -sU -p 170 <host>
nc -zv <host> 170

Block it in the firewall

sudo ufw deny 170/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 170" -Direction Inbound -LocalPort 170 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 170 used for?

Port 170 is assigned by IANA to print-srv (Network PostScript).

Is port 170 TCP or UDP?

Port 170 is registered for TCP and UDP.

Is it safe to open port 170?

It depends on the program that listens on it. Open it only for a service you know and only to the networks that need it. Answer only the networks that need the service (no open resolvers, relays or reflectors).

How do I check if port 170 is open?

On Linux run "ss -ltnup 'sport = :170'", on macOS "lsof -nP -i :170", and on Windows "netstat -ano | findstr :170" to see the local process. From another machine, "nmap -p 170 <host>" shows whether it is reachable.

05 Related
:53 DNS tcp · udp · moderate risk :135 MS RPC tcp · udp · high risk :123 NTP udp · tcp · moderate risk :67 DHCP server udp · tcp · moderate risk :111 rpcbind tcp · udp · high risk :9100 Raw printing (JetDirect) tcp · udp · high risk :631 IPP / CUPS tcp · udp · high risk :5353 mDNS udp · tcp · moderate risk

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