Registered · Cross-platform

3551 apcupsd

TCP Yes
UDP
SCTP
DCCP

What it is

APC UPS daemon information port.

When / why

APC UPS monitoring.

Protocol status detail

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

Port range

Registered (1024–49151). Assigned by IANA on request; usable without elevated privileges on most systems.

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Firewall rules for port 3551

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

ufw

sudo ufw allow proto tcp from <source> to any port 3551

Allow TCP 3551 (apcupsd). 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="3551" protocol="tcp" accept'

Allow TCP 3551 (apcupsd) from <source>. Run 'firewall-cmd --reload' afterwards.

nftables

nft add rule inet filter input ip saddr <source> tcp dport 3551 accept

Allow TCP 3551 (apcupsd). Assumes table 'inet filter' with an 'input' chain.

iptables

sudo iptables -A INPUT -p tcp -s <source> --dport 3551 -j ACCEPT

Allow TCP 3551 (apcupsd). Persist with iptables-save/netfilter-persistent.

Azure NSG

az network nsg rule create -g <resource-group> --nsg-name <nsg> -n Allow-apcupsd-3551 --priority 1000 --access Allow --direction Inbound --protocol TCP --source-address-prefixes <source> --destination-port-ranges 3551

Inbound rule for 3551 (apcupsd). 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=3551,ToPort=3551,IpRanges="[{CidrIp=<source-cidr>}]"

Inbound TCP 3551 (apcupsd). Replace <source-cidr> (e.g. 10.0.0.0/16).

GCP firewall

gcloud compute firewall-rules create allow-apcupsd-3551 --direction=INGRESS --action=ALLOW --rules=tcp:3551 --source-ranges=<source-cidr> --network=<network>

Ingress rule for 3551 (apcupsd). Scope with --source-ranges and optionally --target-tags.

Windows netsh

netsh advfirewall firewall add rule name="Allow apcupsd 3551/TCP" dir=in action=allow protocol=TCP localport=3551 remoteip=<source>

Inbound TCP 3551 (apcupsd). Set remoteip to a host/subnet; 'any' is discouraged.

Windows PowerShell

New-NetFirewallRule -DisplayName "Allow apcupsd 3551/TCP" -Direction Inbound -Action Allow -Protocol TCP -LocalPort 3551 -RemoteAddress <source>

Inbound TCP 3551 (apcupsd). 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.