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Port 159 (nss-routing)

IANA assigns port 159 to nss-routing: NSS-Routing.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
nss-routing TCP NSS-Routing Yakov Rekhter -
nss-routing UDP NSS-Routing Yakov Rekhter -

Check what is listening on port 159

Linux: is anything listening on TCP 159?
sudo ss -tlnp 'sport = :159'
Linux: UDP 159
sudo ss -ulnp 'sport = :159'
Linux / macOS: which process owns the port
sudo lsof -nP -i :159
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':159 '
Windows (Command Prompt)
netstat -ano | findstr :159
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 159 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 159
From Windows
Test-NetConnection HOST -Port 159
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 159

Block port 159 in the firewall

ufw
sudo ufw deny 159/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 159 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 159 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 159' -Direction Inbound -Protocol TCP -LocalPort 159 -Action Block
ufw
sudo ufw deny 159/udp
iptables
sudo iptables -A INPUT -p udp --dport 159 -j DROP
nftables
sudo nft add rule inet filter input udp dport 159 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 159' -Direction Inbound -Protocol UDP -LocalPort 159 -Action Block

Related ports

157knet-cmp158pcmail-srv160sgmp-traps161SNMP

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