Well-known · Windows

42 WINS / Host Name Server

TCP Assigned
UDP Yes
SCTP
DCCP

What it is

Microsoft WINS replication uses this Host Name Server port.

When / why

WINS replication between Windows name servers.

Protocol status detail

TransportStatusMeaning
TCP Assigned Assigned by IANA, but not 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.

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Firewall rules for port 42

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 udp from <source> to any port 42

Allow UDP 42 (WINS / Host Name Server). 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="42" protocol="udp" accept'

Allow UDP 42 (WINS / Host Name Server) from <source>. Run 'firewall-cmd --reload' afterwards.

nftables

nft add rule inet filter input ip saddr <source> udp dport 42 accept

Allow UDP 42 (WINS / Host Name Server). Assumes table 'inet filter' with an 'input' chain.

iptables

sudo iptables -A INPUT -p udp -s <source> --dport 42 -j ACCEPT

Allow UDP 42 (WINS / Host Name Server). Persist with iptables-save/netfilter-persistent.

Azure NSG

az network nsg rule create -g <resource-group> --nsg-name <nsg> -n Allow-winshostnameserver-42 --priority 1000 --access Allow --direction Inbound --protocol UDP --source-address-prefixes <source> --destination-port-ranges 42

Inbound rule for 42 (WINS / Host Name Server). 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=udp,FromPort=42,ToPort=42,IpRanges="[{CidrIp=<source-cidr>}]"

Inbound UDP 42 (WINS / Host Name Server). Replace <source-cidr> (e.g. 10.0.0.0/16).

GCP firewall

gcloud compute firewall-rules create allow-winshostnameserver-42 --direction=INGRESS --action=ALLOW --rules=udp:42 --source-ranges=<source-cidr> --network=<network>

Ingress rule for 42 (WINS / Host Name Server). Scope with --source-ranges and optionally --target-tags.

Windows netsh

netsh advfirewall firewall add rule name="Allow WINS / Host Name Server 42/UDP" dir=in action=allow protocol=UDP localport=42 remoteip=<source>

Inbound UDP 42 (WINS / Host Name Server). Set remoteip to a host/subnet; 'any' is discouraged.

Windows PowerShell

New-NetFirewallRule -DisplayName "Allow WINS / Host Name Server 42/UDP" -Direction Inbound -Action Allow -Protocol UDP -LocalPort 42 -RemoteAddress <source>

Inbound UDP 42 (WINS / Host Name Server). 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.