Port 691

msexch-routing · TCP/UDP

RangeSystem/well-known port (0–1023)
ProtocolTCP/UDP
Servicemsexch-routing

Frequently asked questions

What is port 691 used for?

Port 691 is registered with the IANA for msexch-routing (TCP/UDP). Description: MS Exchange Routing.

Is port 691 a well-known port?

Yes. Port 691 is in the range 0–1023 (system or well-known ports). On Linux and macOS only privileged processes may bind to these ports.

How do I check whether port 691 is open?

Locally on Linux with ss -tulpn | grep ':691\b', on Windows with netstat -ano | findstr :691. To test a remote host use Test-NetConnection <host> -Port 691 in PowerShell or nc -zv <host> 691 on Linux/macOS.

How do I open port 691 in the firewall?

Ubuntu/Debian (ufw): sudo ufw allow 691/tcp. Fedora/RHEL (firewalld): sudo firewall-cmd --add-port=691/tcp --permanent, then firewall-cmd --reload. Windows (PowerShell as administrator): New-NetFirewallRule -DisplayName "Port 691" -Direction Inbound -Protocol TCP -LocalPort 691 -Action Allow.

IANA registry entries

ProtocolServiceDescription (IANA)
TCPmsexch-routingMS Exchange Routing
UDPmsexch-routingMS Exchange Routing

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