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Port 3388 (cbserver)

IANA assigns port 3388 to cbserver: CB Server.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
cbserver TCP CB Server Allen Wei -
cbserver UDP CB Server Allen Wei -

Check what is listening on port 3388

Linux: is anything listening on TCP 3388?
sudo ss -tlnp 'sport = :3388'
Linux: UDP 3388
sudo ss -ulnp 'sport = :3388'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3388
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3388 '
Windows (Command Prompt)
netstat -ano | findstr :3388
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3388 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3388
From Windows
Test-NetConnection HOST -Port 3388
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3388

Block port 3388 in the firewall

ufw
sudo ufw deny 3388/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3388 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3388 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3388' -Direction Inbound -Protocol TCP -LocalPort 3388 -Action Block
ufw
sudo ufw deny 3388/udp
iptables
sudo iptables -A INPUT -p udp --dport 3388 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3388 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3388' -Direction Inbound -Protocol UDP -LocalPort 3388 -Action Block

Related ports

3386gprs-data, gprs-sig3387backroomnet3389RDP (Remote Desktop)3390dsc

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