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Port 2176 (rapi)

IANA assigns port 2176 to rapi: Microsoft ActiveSync Remote API.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
rapi TCP Microsoft ActiveSync Remote API Jon Xu -
rapi UDP Microsoft ActiveSync Remote API Jon Xu -

Registry dates for this port: registered 2005-08.

Check what is listening on port 2176

Linux: is anything listening on TCP 2176?
sudo ss -tlnp 'sport = :2176'
Linux: UDP 2176
sudo ss -ulnp 'sport = :2176'
Linux / macOS: which process owns the port
sudo lsof -nP -i :2176
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':2176 '
Windows (Command Prompt)
netstat -ano | findstr :2176
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 2176 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 2176
From Windows
Test-NetConnection HOST -Port 2176
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 2176

Block port 2176 in the firewall

ufw
sudo ufw deny 2176/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 2176 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 2176 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 2176' -Direction Inbound -Protocol TCP -LocalPort 2176 -Action Block
ufw
sudo ufw deny 2176/udp
iptables
sudo iptables -A INPUT -p udp --dport 2176 -j DROP
nftables
sudo nft add rule inet filter input udp dport 2176 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 2176' -Direction Inbound -Protocol UDP -LocalPort 2176 -Action Block

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