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Port 2890 (cspclmulti)

IANA assigns port 2890 to cspclmulti: CSPCLMULTI.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
cspclmulti TCP CSPCLMULTI Yoneda Terumasa -
cspclmulti UDP CSPCLMULTI Yoneda Terumasa -

Check what is listening on port 2890

Linux: is anything listening on TCP 2890?
sudo ss -tlnp 'sport = :2890'
Linux: UDP 2890
sudo ss -ulnp 'sport = :2890'
Linux / macOS: which process owns the port
sudo lsof -nP -i :2890
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':2890 '
Windows (Command Prompt)
netstat -ano | findstr :2890
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 2890 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 2890
From Windows
Test-NetConnection HOST -Port 2890
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 2890

Block port 2890 in the firewall

ufw
sudo ufw deny 2890/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 2890 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 2890 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 2890' -Direction Inbound -Protocol TCP -LocalPort 2890 -Action Block
ufw
sudo ufw deny 2890/udp
iptables
sudo iptables -A INPUT -p udp --dport 2890 -j DROP
nftables
sudo nft add rule inet filter input udp dport 2890 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 2890' -Direction Inbound -Protocol UDP -LocalPort 2890 -Action Block

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