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// Other services

Port 33435: IP Multicast Traceroute

Port 33435 is assigned by IANA to mtrace (IP Multicast Traceroute).

33435

How mtrace works

Other services
client:33435mtraceresponse client:33435mtraceresponse

The client sends a request to port 33435 and the mtrace service answers.

Transport
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 33435 dangerous?

We have no specific security note for port 33435. 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 33435

ServicePortTransportDescriptionReferenceUpdated
mtrace 33435 UDP IP Multicast Traceroute
Reported: Known Unauthorized Use on port 33435
 RFC 8487 2019-08-09
-33435-Reserved--

// source: IANA service name and port number registry

03 Check it

Which program uses port 33435, and is it reachable?

Linux

sudo ss -ltnup 'sport = :33435'      # process listening on 33435
sudo lsof -nP -i :33435

macOS

sudo lsof -nP -i :33435

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 33435 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 33435
netstat -ano | findstr :33435

From another machine

nmap -p 33435 -sV <host>
sudo nmap -sU -p 33435 <host>
nc -zv <host> 33435

Block it in the firewall

sudo ufw deny 33435/udp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 33435" -Direction Inbound -LocalPort 33435 -Protocol UDP -Action Block  # Windows
04 FAQ
What is port 33435 used for?

Port 33435 is assigned by IANA to mtrace (IP Multicast Traceroute).

Is port 33435 TCP or UDP?

Port 33435 is registered for UDP.

Is it safe to open port 33435?

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 33435 is open?

On Linux run "ss -ltnup 'sport = :33435'", on macOS "lsof -nP -i :33435", and on Windows "netstat -ano | findstr :33435" to see the local process. From another machine, "nmap -p 33435 <host>" shows whether it is reachable.

05 Related
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