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// Directory & authentication

Port 1615: NetBill Authorization Server

Port 1615 is assigned by IANA to netbill-auth (NetBill Authorization Server).

1615

How netbill-auth works

Directory & authentication
userdirectorynetbill-authresponse userdirectorynetbill-authresponse

The client proves who it is on port 1615 and gets an answer (or a ticket) it can use with other services.

Transport
TCP · UDP
Exposure risk
not rated depends on the program listening
Encryption
Unknownnot stated by the registry
IANA status
Assigned1 registered service
Range
Registered (1024-49151)
Category
Directory & authentication
01 Security

Is port 1615 dangerous?

We have no specific security note for port 1615. Its risk depends on the program actually listening on it. General advice for directory & authentication services:

  • Keep directory and authentication services on internal networks.
  • Require signing or TLS and disable anonymous queries.
  • Monitor authentication failures for spraying and brute force.
02 Registry

IANA registry entries for port 1615

ServicePortTransportDescriptionReferenceUpdated
netbill-auth 1615 TCP, UDP NetBill Authorization Server - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 1615, and is it reachable?

Linux

sudo ss -ltnup 'sport = :1615'      # process listening on 1615
sudo lsof -nP -i :1615

macOS

sudo lsof -nP -i :1615

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 1615 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 1615
netstat -ano | findstr :1615

From another machine

nmap -p 1615 -sV <host>
sudo nmap -sU -p 1615 <host>
nc -zv <host> 1615

Block it in the firewall

sudo ufw deny 1615/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 1615" -Direction Inbound -LocalPort 1615 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 1615 used for?

Port 1615 is assigned by IANA to netbill-auth (NetBill Authorization Server).

Is port 1615 TCP or UDP?

Port 1615 is registered for TCP and UDP.

Is it safe to open port 1615?

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. Keep directory and authentication services on internal networks.

How do I check if port 1615 is open?

On Linux run "ss -ltnup 'sport = :1615'", on macOS "lsof -nP -i :1615", and on Windows "netstat -ano | findstr :1615" to see the local process. From another machine, "nmap -p 1615 <host>" shows whether it is reachable.

05 Related
:389 LDAP tcp · udp · high risk :636 LDAPS tcp · udp · moderate risk :88 Kerberos tcp · udp · high risk :3268 Global Catalog (LDAP) tcp · udp · high risk :1812 RADIUS udp · tcp · moderate risk :31 MSG Authentication tcp · udp :49 Login Host Protocol (TACACS) tcp · udp :56 XNS Authentication tcp · udp

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