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Port 3511 (webmail-2)

IANA assigns port 3511 to webmail-2: WebMail/2.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
webmail-2 TCP WebMail/2 Dimitris Michelinaki -
webmail-2 UDP WebMail/2 Dimitris Michelinaki -

Registry dates for this port: registered 2002-05.

Check what is listening on port 3511

Linux: is anything listening on TCP 3511?
sudo ss -tlnp 'sport = :3511'
Linux: UDP 3511
sudo ss -ulnp 'sport = :3511'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3511
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3511 '
Windows (Command Prompt)
netstat -ano | findstr :3511
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3511 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3511
From Windows
Test-NetConnection HOST -Port 3511
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3511

Block port 3511 in the firewall

ufw
sudo ufw deny 3511/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3511 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3511 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3511' -Direction Inbound -Protocol TCP -LocalPort 3511 -Action Block
ufw
sudo ufw deny 3511/udp
iptables
sudo iptables -A INPUT -p udp --dport 3511 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3511 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3511' -Direction Inbound -Protocol UDP -LocalPort 3511 -Action Block

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3509vt-ssl3510xss-port3512aztec3513arcpd

All port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.