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Port 2873 (psrt)

IANA assigns port 2873 to psrt: PubSub Realtime Telemetry Protocol.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
psrt TCP PubSub Realtime Telemetry Protocol Altertech -
psrt UDP PubSub Realtime Telemetry Protocol Altertech -

Registry dates for this port: registered 2021-11-12.

Check what is listening on port 2873

Linux: is anything listening on TCP 2873?
sudo ss -tlnp 'sport = :2873'
Linux: UDP 2873
sudo ss -ulnp 'sport = :2873'
Linux / macOS: which process owns the port
sudo lsof -nP -i :2873
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':2873 '
Windows (Command Prompt)
netstat -ano | findstr :2873
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 2873 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 2873
From Windows
Test-NetConnection HOST -Port 2873
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 2873

Block port 2873 in the firewall

ufw
sudo ufw deny 2873/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 2873 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 2873 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 2873' -Direction Inbound -Protocol TCP -LocalPort 2873 -Action Block
ufw
sudo ufw deny 2873/udp
iptables
sudo iptables -A INPUT -p udp --dport 2873 -j DROP
nftables
sudo nft add rule inet filter input udp dport 2873 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 2873' -Direction Inbound -Protocol UDP -LocalPort 2873 -Action Block

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2871msi-selectplay2872radix2874dxmessagebase12875dxmessagebase2

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