CyberHunter
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// Network services

Port 159: NSS-Routing

Port 159 is assigned by IANA to nss-routing (NSS-Routing).

159

How nss-routing works

Network services
client:159nss-routingresponse client:159nss-routingresponse

The client sends a request to port 159 and the nss-routing 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 159 dangerous?

We have no specific security note for port 159. 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 159

ServicePortTransportDescriptionReferenceUpdated
nss-routing 159 TCP, UDP NSS-Routing - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 159, and is it reachable?

Linux

sudo ss -ltnup 'sport = :159'      # process listening on 159
sudo lsof -nP -i :159

macOS

sudo lsof -nP -i :159

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 159 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 159
netstat -ano | findstr :159

From another machine

nmap -p 159 -sV <host>
sudo nmap -sU -p 159 <host>
nc -zv <host> 159

Block it in the firewall

sudo ufw deny 159/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 159" -Direction Inbound -LocalPort 159 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 159 used for?

Port 159 is assigned by IANA to nss-routing (NSS-Routing).

Is port 159 TCP or UDP?

Port 159 is registered for TCP and UDP.

Is it safe to open port 159?

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 159 is open?

On Linux run "ss -ltnup 'sport = :159'", on macOS "lsof -nP -i :159", and on Windows "netstat -ano | findstr :159" to see the local process. From another machine, "nmap -p 159 <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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