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// Other services

Port 748: Russell Info Sci Calendar Manager

Port 748 is assigned by IANA to ris-cm (Russell Info Sci Calendar Manager).

748

How ris-cm works

Other services
client:748ris-cmresponse client:748ris-cmresponse

The client sends a request to port 748 and the ris-cm 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
Other services
01 Security

Is port 748 dangerous?

We have no specific security note for port 748. Its risk depends on the program actually listening on it. General advice for other services services:

  • Close the port if nothing on the host needs it.
  • Identify the process that listens on it (commands below) before opening it in a firewall.
  • Expose a service only to the networks that use it.
02 Registry

IANA registry entries for port 748

ServicePortTransportDescriptionReferenceUpdated
ris-cm 748 TCP, UDP Russell Info Sci Calendar Manager - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 748, and is it reachable?

Linux

sudo ss -ltnup 'sport = :748'      # process listening on 748
sudo lsof -nP -i :748

macOS

sudo lsof -nP -i :748

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 748 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 748
netstat -ano | findstr :748

From another machine

nmap -p 748 -sV <host>
sudo nmap -sU -p 748 <host>
nc -zv <host> 748

Block it in the firewall

sudo ufw deny 748/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 748" -Direction Inbound -LocalPort 748 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 748 used for?

Port 748 is assigned by IANA to ris-cm (Russell Info Sci Calendar Manager).

Is port 748 TCP or UDP?

Port 748 is registered for TCP and UDP.

Is it safe to open port 748?

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. Close the port if nothing on the host needs it.

How do I check if port 748 is open?

On Linux run "ss -ltnup 'sport = :748'", on macOS "lsof -nP -i :748", and on Windows "netstat -ano | findstr :748" to see the local process. From another machine, "nmap -p 748 <host>" shows whether it is reachable.

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