Port 623: Intelligent Platform Management Interface over RMCP
UDP 623 carries the ASF Remote Management and Control Protocol, which IPMI uses to reach a server's baseboard management controller (BMC). CISA lists HP Integrated Lights Out and Dell DRAC among the affected management products. IANA assigns TCP 623 to the DMTF out-of-band web services management protocol.
Port Details
Security Exposure
IPMI provides low-level access to a server that can override operating system controls. CISA warns that IPMI systems connected to the internet are easy to identify and access, and that the default-enabled cipher 0 option on many devices allows authentication to be bypassed. A compromised BMC puts the host's confidentiality, integrity and availability at risk.
Hardening
- +Restrict IPMI traffic to a dedicated management VLAN with strict network controls.
- +Disable cipher 0 and anonymous logins on every BMC.
- +Set strong, unique passwords for IPMI accounts.
- +Enable encryption on IPMI interfaces where the hardware supports it.
- +Sanitize BMC flash memory at end of life to remove stored passwords.
Monitoring
Scan for IPMI responding outside the trusted management network, as CISA recommends, and monitor the management network for unusual activity. Collect BMC event and login logs centrally.
Tools for Auditing and Monitoring IPMI (RMCP)
Nmap
Free / CommercialNetwork discovery scanner and port auditor for discovering live hosts, open ports, running services, and OS fingerprints.
Nessus
CommercialTenable vulnerability scanner with the industry’s largest plugin library; time-limited free Essentials license.
OPENVAS
Free / CommercialFull-featured vulnerability scanner for identifying security flaws, missing patches, and weak configs across network hosts.
Related Tool Categories
Frequently Asked Questions
What is port 623 used for?→
It is the IPMI and RMCP port for out-of-band server management through a BMC. CISA notes IPMI traffic usually uses UDP port 623.
Should IPMI be reachable from the internet?→
No. CISA recommends restricting IPMI to trusted internal networks, preferably a separate management VLAN.
Sources
Port assignments from the IANA Service Name and Transport Protocol Port Number Registry. Services can be configured to run on any port, so traffic on port 623 is not guaranteed to be IPMI (RMCP). Exploited-in-the-wild data from the CISA KEV catalog (CC0).