Well-known · Cross-platform

427 SLP

TCP Yes
UDP Yes
SCTP
DCCP

What it is

Service Location Protocol.

When / why

Service discovery (e.g. VMware). UDP/427 is a known amplifier — restrict.

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.

Port range

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

Browse all ports →

Firewall rules for port 427

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

⚠ UDP amplification risk — restrict or disable on internet-facing interfaces.

ufw

sudo ufw allow proto tcp from <source> to any port 427

Allow TCP 427 (SLP). Replace <source> with the network/host that should reach it.

sudo ufw allow proto udp from <source> to any port 427

Allow UDP 427 (SLP). 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="427" protocol="tcp" accept'

Allow TCP 427 (SLP) from <source>. Run 'firewall-cmd --reload' afterwards.

sudo firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="<source>" port port="427" protocol="udp" accept'

Allow UDP 427 (SLP) from <source>. Run 'firewall-cmd --reload' afterwards.

nftables

nft add rule inet filter input ip saddr <source> tcp dport 427 accept

Allow TCP 427 (SLP). Assumes table 'inet filter' with an 'input' chain.

nft add rule inet filter input ip saddr <source> udp dport 427 accept

Allow UDP 427 (SLP). Assumes table 'inet filter' with an 'input' chain.

iptables

sudo iptables -A INPUT -p tcp -s <source> --dport 427 -j ACCEPT

Allow TCP 427 (SLP). Persist with iptables-save/netfilter-persistent.

sudo iptables -A INPUT -p udp -s <source> --dport 427 -j ACCEPT

Allow UDP 427 (SLP). Persist with iptables-save/netfilter-persistent.

Azure NSG

az network nsg rule create -g <resource-group> --nsg-name <nsg> -n Allow-slp-427 --priority 1000 --access Allow --direction Inbound --protocol "*" --source-address-prefixes <source> --destination-port-ranges 427

Inbound rule for 427 (SLP). 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=427,ToPort=427,IpRanges="[{CidrIp=<source-cidr>}]"

Inbound TCP 427 (SLP). 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=427,ToPort=427,IpRanges="[{CidrIp=<source-cidr>}]"

Inbound UDP 427 (SLP). Replace <source-cidr> (e.g. 10.0.0.0/16).

GCP firewall

gcloud compute firewall-rules create allow-slp-427 --direction=INGRESS --action=ALLOW --rules=tcp:427,udp:427 --source-ranges=<source-cidr> --network=<network>

Ingress rule for 427 (SLP). Scope with --source-ranges and optionally --target-tags.

Windows netsh

netsh advfirewall firewall add rule name="Allow SLP 427/TCP" dir=in action=allow protocol=TCP localport=427 remoteip=<source>

Inbound TCP 427 (SLP). Set remoteip to a host/subnet; 'any' is discouraged.

netsh advfirewall firewall add rule name="Allow SLP 427/UDP" dir=in action=allow protocol=UDP localport=427 remoteip=<source>

Inbound UDP 427 (SLP). Set remoteip to a host/subnet; 'any' is discouraged.

Windows PowerShell

New-NetFirewallRule -DisplayName "Allow SLP 427/TCP" -Direction Inbound -Action Allow -Protocol TCP -LocalPort 427 -RemoteAddress <source>

Inbound TCP 427 (SLP). Replace <source> with a host or subnet.

New-NetFirewallRule -DisplayName "Allow SLP 427/UDP" -Direction Inbound -Action Allow -Protocol UDP -LocalPort 427 -RemoteAddress <source>

Inbound UDP 427 (SLP). 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.