Port 3332 (mcs-mailsvr)

IANA assigns port 3332 to mcs-mailsvr: MCS Mail Server.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference

mcs-mailsvr TCP MCS Mail Server Patti Jo Newsom -

mcs-mailsvr UDP MCS Mail Server Patti Jo Newsom -

Linux: is anything listening on TCP 3332?

sudo ss -tlnp 'sport = :3332'

Linux: UDP 3332

sudo ss -ulnp 'sport = :3332'

Linux / macOS: which process owns the port

sudo lsof -nP -i :3332

Older Linux / BSD (net-tools)

sudo netstat -tlnp | grep ':3332 '

Windows (Command Prompt)

netstat -ano | findstr :3332

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3332 -State Listen | Select LocalAddress,OwningProcess

From another machine

nc -vz -w 5 HOST 3332

From Windows

Test-NetConnection HOST -Port 3332

UDP probe (no reply does not prove it is closed)

nc -vzu -w 5 HOST 3332

ufw

sudo ufw deny 3332/tcp

iptables

sudo iptables -A INPUT -p tcp --dport 3332 -j DROP

nftables

sudo nft add rule inet filter input tcp dport 3332 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block TCP 3332' -Direction Inbound -Protocol TCP -LocalPort 3332 -Action Block

ufw

sudo ufw deny 3332/udp

iptables

sudo iptables -A INPUT -p udp --dport 3332 -j DROP

nftables

sudo nft add rule inet filter input udp dport 3332 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block UDP 3332' -Direction Inbound -Protocol UDP -LocalPort 3332 -Action Block

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Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.