623
IPMI out-of-band server hardware management
Intelligent Platform Management Interface
What is port 623?
UDP port 623 is used by IPMI (Intelligent Platform Management Interface), an out-of-band server management system that operates independently of the host OS via a dedicated BMC (Baseboard Management Controller). It enables remote power control, serial console access, and hardware monitoring. IPMI has a well-documented history of security issues including weak default passwords, cipher suite downgrade attacks, and buffer overflows. Never expose IPMI to the internet.
Quick checks
$
nc -zv example.com 623
$
nmap -p 623 example.com