CyberHunter
Local dataset, no network
// Other services

Port 1100: MCTP

Port 1100 is assigned by IANA to mctp (MCTP).

1100

How mctp works

Other services
client:1100mctpresponse client:1100mctpresponse

The client sends a request to port 1100 and the mctp 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
Other services
01 Security

Is port 1100 dangerous?

We have no specific security note for port 1100. 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 1100

ServicePortTransportDescriptionReferenceUpdated
mctp 1100 TCP, UDP MCTP - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 1100, and is it reachable?

Linux

sudo ss -ltnup 'sport = :1100'      # process listening on 1100
sudo lsof -nP -i :1100

macOS

sudo lsof -nP -i :1100

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 1100 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 1100
netstat -ano | findstr :1100

From another machine

nmap -p 1100 -sV <host>
sudo nmap -sU -p 1100 <host>
nc -zv <host> 1100

Block it in the firewall

sudo ufw deny 1100/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 1100" -Direction Inbound -LocalPort 1100 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 1100 used for?

Port 1100 is assigned by IANA to mctp (MCTP).

Is port 1100 TCP or UDP?

Port 1100 is registered for TCP and UDP.

Is it safe to open port 1100?

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 1100 is open?

On Linux run "ss -ltnup 'sport = :1100'", on macOS "lsof -nP -i :1100", and on Windows "netstat -ano | findstr :1100" to see the local process. From another machine, "nmap -p 1100 <host>" shows whether it is reachable.

05 Related
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