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Port 3383 (esp-lm)

IANA assigns port 3383 to esp-lm: Enterprise Software Products License Manager.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
esp-lm TCP Enterprise Software Products License Manager George Rudy -
esp-lm UDP Enterprise Software Products License Manager George Rudy -

Check what is listening on port 3383

Linux: is anything listening on TCP 3383?
sudo ss -tlnp 'sport = :3383'
Linux: UDP 3383
sudo ss -ulnp 'sport = :3383'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3383
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3383 '
Windows (Command Prompt)
netstat -ano | findstr :3383
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3383 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3383
From Windows
Test-NetConnection HOST -Port 3383
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3383

Block port 3383 in the firewall

ufw
sudo ufw deny 3383/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3383 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3383 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3383' -Direction Inbound -Protocol TCP -LocalPort 3383 -Action Block
ufw
sudo ufw deny 3383/udp
iptables
sudo iptables -A INPUT -p udp --dport 3383 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3383 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3383' -Direction Inbound -Protocol UDP -LocalPort 3383 -Action Block

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