Well-known · Cross-platform

623 IPMI / ASF-RMCP

TCP Yes
UDP Yes
SCTP —
DCCP —

What it is

Out-of-band server management (BMC) — IPMI/RMCP.

When / why

iDRAC/iLO/BMC lights-out management. Isolate on a dedicated management VLAN; never internet-facing.

Protocol status detail

TransportStatusMeaning
TCP Yes Assigned by IANA and standardized, specified, or widely used on this port.
UDP Yes Assigned by IANA and standardized, specified, or widely used on this port.
SCTP — Not applicable for this transport.
DCCP — Not applicable for this transport.
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Port range

Well-known (0–1023). System port for a core service. On Unix-like systems, binding it requires superuser privileges.

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Firewall rules for port 623

Copy-ready inbound rules for the active transports. Replace every <source> placeholder with the specific host, subnet, or CIDR that should reach this port.

⚠ High exposure risk — this service should never be reachable from untrusted networks. Scope the rule to a management subnet or VPN.

ufw

sudo ufw allow proto tcp from <source> to any port 623

Allow TCP 623 (IPMI / ASF-RMCP). Replace <source> with the network/host that should reach it.

sudo ufw allow proto udp from <source> to any port 623

Allow UDP 623 (IPMI / ASF-RMCP). Replace <source> with the network/host that should reach it.

firewalld

sudo firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="<source>" port port="623" protocol="tcp" accept'

Allow TCP 623 (IPMI / ASF-RMCP) from <source>. Run 'firewall-cmd --reload' afterwards.

sudo firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="<source>" port port="623" protocol="udp" accept'

Allow UDP 623 (IPMI / ASF-RMCP) from <source>. Run 'firewall-cmd --reload' afterwards.

nftables

nft add rule inet filter input ip saddr <source> tcp dport 623 accept

Allow TCP 623 (IPMI / ASF-RMCP). Assumes table 'inet filter' with an 'input' chain.

nft add rule inet filter input ip saddr <source> udp dport 623 accept

Allow UDP 623 (IPMI / ASF-RMCP). Assumes table 'inet filter' with an 'input' chain.

iptables

sudo iptables -A INPUT -p tcp -s <source> --dport 623 -j ACCEPT

Allow TCP 623 (IPMI / ASF-RMCP). Persist with iptables-save/netfilter-persistent.

sudo iptables -A INPUT -p udp -s <source> --dport 623 -j ACCEPT

Allow UDP 623 (IPMI / ASF-RMCP). Persist with iptables-save/netfilter-persistent.

Azure NSG

az network nsg rule create -g <resource-group> --nsg-name <nsg> -n Allow-ipmiasfrmcp-623 --priority 1000 --access Allow --direction Inbound --protocol "*" --source-address-prefixes <source> --destination-port-ranges 623

Inbound rule for 623 (IPMI / ASF-RMCP). Set <source> to a CIDR; lower priority number = higher precedence.

AWS Security Group

aws ec2 authorize-security-group-ingress --group-id <sg-id> --ip-permissions IpProtocol=tcp,FromPort=623,ToPort=623,IpRanges="[{CidrIp=<source-cidr>}]"

Inbound TCP 623 (IPMI / ASF-RMCP). Replace <source-cidr> (e.g. 10.0.0.0/16).

aws ec2 authorize-security-group-ingress --group-id <sg-id> --ip-permissions IpProtocol=udp,FromPort=623,ToPort=623,IpRanges="[{CidrIp=<source-cidr>}]"

Inbound UDP 623 (IPMI / ASF-RMCP). Replace <source-cidr> (e.g. 10.0.0.0/16).

GCP firewall

gcloud compute firewall-rules create allow-ipmiasfrmcp-623 --direction=INGRESS --action=ALLOW --rules=tcp:623,udp:623 --source-ranges=<source-cidr> --network=<network>

Ingress rule for 623 (IPMI / ASF-RMCP). Scope with --source-ranges and optionally --target-tags.

Windows netsh

netsh advfirewall firewall add rule name="Allow IPMI / ASF-RMCP 623/TCP" dir=in action=allow protocol=TCP localport=623 remoteip=<source>

Inbound TCP 623 (IPMI / ASF-RMCP). Set remoteip to a host/subnet; 'any' is discouraged.

netsh advfirewall firewall add rule name="Allow IPMI / ASF-RMCP 623/UDP" dir=in action=allow protocol=UDP localport=623 remoteip=<source>

Inbound UDP 623 (IPMI / ASF-RMCP). Set remoteip to a host/subnet; 'any' is discouraged.

Windows PowerShell

New-NetFirewallRule -DisplayName "Allow IPMI / ASF-RMCP 623/TCP" -Direction Inbound -Action Allow -Protocol TCP -LocalPort 623 -RemoteAddress <source>

Inbound TCP 623 (IPMI / ASF-RMCP). Replace <source> with a host or subnet.

New-NetFirewallRule -DisplayName "Allow IPMI / ASF-RMCP 623/UDP" -Direction Inbound -Action Allow -Protocol UDP -LocalPort 623 -RemoteAddress <source>

Inbound UDP 623 (IPMI / ASF-RMCP). Replace <source> with a host or subnet.

Rules are generated only for transports marked active for this port. They default to an inbound allow with an explicit source placeholder — never any. Review direction, scope, and rule precedence before applying in production.