CyberHunter
Local dataset, no network
// Other services

Port 3511: WebMail/2

Port 3511 is assigned by IANA to webmail-2 (WebMail/2).

3511

How webmail-2 works

Other services
client:3511webmail-2response client:3511webmail-2response

The client sends a request to port 3511 and the webmail-2 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 3511 dangerous?

We have no specific security note for port 3511. 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 3511

ServicePortTransportDescriptionReferenceUpdated
webmail-2 3511 TCP, UDP WebMail/2 - 2002-05

// source: IANA service name and port number registry

03 Check it

Which program uses port 3511, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3511'      # process listening on 3511
sudo lsof -nP -i :3511

macOS

sudo lsof -nP -i :3511

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3511 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3511
netstat -ano | findstr :3511

From another machine

nmap -p 3511 -sV <host>
sudo nmap -sU -p 3511 <host>
nc -zv <host> 3511

Block it in the firewall

sudo ufw deny 3511/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3511" -Direction Inbound -LocalPort 3511 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3511 used for?

Port 3511 is assigned by IANA to webmail-2 (WebMail/2).

Is port 3511 TCP or UDP?

Port 3511 is registered for TCP and UDP.

Is it safe to open port 3511?

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 3511 is open?

On Linux run "ss -ltnup 'sport = :3511'", on macOS "lsof -nP -i :3511", and on Windows "netstat -ano | findstr :3511" to see the local process. From another machine, "nmap -p 3511 <host>" shows whether it is reachable.

05 Related
:4444 Metasploit default / krb524 tcp · udp · high risk :31337 Back Orifice / elite tcp · udp · high risk :1 TCP Port Service Multiplexer tcp · udp :5 Remote Job Entry tcp · udp :9 Discard tcp · udp · sctp · dccp :11 Active Users tcp · udp :17 Quote of the Day tcp · udp :18 Message Send Protocol (historic) tcp · udp

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