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Port 2104 (zephyr-hm)

IANA assigns port 2104 to zephyr-hm: Zephyr hostmanager.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
zephyr-hm TCP Zephyr hostmanager Greg Hudson -
zephyr-hm UDP Zephyr hostmanager Greg Hudson -

Check what is listening on port 2104

Linux: is anything listening on TCP 2104?
sudo ss -tlnp 'sport = :2104'
Linux: UDP 2104
sudo ss -ulnp 'sport = :2104'
Linux / macOS: which process owns the port
sudo lsof -nP -i :2104
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':2104 '
Windows (Command Prompt)
netstat -ano | findstr :2104
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 2104 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 2104
From Windows
Test-NetConnection HOST -Port 2104
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 2104

Block port 2104 in the firewall

ufw
sudo ufw deny 2104/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 2104 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 2104 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 2104' -Direction Inbound -Protocol TCP -LocalPort 2104 -Action Block
ufw
sudo ufw deny 2104/udp
iptables
sudo iptables -A INPUT -p udp --dport 2104 -j DROP
nftables
sudo nft add rule inet filter input udp dport 2104 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 2104' -Direction Inbound -Protocol UDP -LocalPort 2104 -Action Block

Related ports

2102zephyr-srv2103zephyr-clt2105minipay2106mzap

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