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// Network services

Port 4750: Simple Service Auto Discovery

Port 4750 is assigned by IANA to ssad (Simple Service Auto Discovery).

4750

How ssad works

Network services
client:4750ssadresponse client:4750ssadresponse

The client sends a request to port 4750 and the ssad 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
Registered (1024-49151)
Category
Network services
01 Security

Is port 4750 dangerous?

We have no specific security note for port 4750. 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 4750

ServicePortTransportDescriptionReferenceUpdated
ssad 4750 TCP, UDP Simple Service Auto Discovery - 2005-12

// source: IANA service name and port number registry

03 Check it

Which program uses port 4750, and is it reachable?

Linux

sudo ss -ltnup 'sport = :4750'      # process listening on 4750
sudo lsof -nP -i :4750

macOS

sudo lsof -nP -i :4750

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 4750 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 4750
netstat -ano | findstr :4750

From another machine

nmap -p 4750 -sV <host>
sudo nmap -sU -p 4750 <host>
nc -zv <host> 4750

Block it in the firewall

sudo ufw deny 4750/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 4750" -Direction Inbound -LocalPort 4750 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 4750 used for?

Port 4750 is assigned by IANA to ssad (Simple Service Auto Discovery).

Is port 4750 TCP or UDP?

Port 4750 is registered for TCP and UDP.

Is it safe to open port 4750?

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 4750 is open?

On Linux run "ss -ltnup 'sport = :4750'", on macOS "lsof -nP -i :4750", and on Windows "netstat -ano | findstr :4750" to see the local process. From another machine, "nmap -p 4750 <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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