Well-known · Linux/Unix

518 ntalk

TCP —
UDP Yes
SCTP —
DCCP —

What it is

New talk messaging daemon.

When / why

Historic chat.

Protocol status detail

TransportStatusMeaning
TCP — Not applicable for this transport.
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 518

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 518

Allow UDP 518 (ntalk). 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="518" protocol="udp" accept'

Allow UDP 518 (ntalk) from <source>. Run 'firewall-cmd --reload' afterwards.

nftables

nft add rule inet filter input ip saddr <source> udp dport 518 accept

Allow UDP 518 (ntalk). Assumes table 'inet filter' with an 'input' chain.

iptables

sudo iptables -A INPUT -p udp -s <source> --dport 518 -j ACCEPT

Allow UDP 518 (ntalk). Persist with iptables-save/netfilter-persistent.

Azure NSG

az network nsg rule create -g <resource-group> --nsg-name <nsg> -n Allow-ntalk-518 --priority 1000 --access Allow --direction Inbound --protocol UDP --source-address-prefixes <source> --destination-port-ranges 518

Inbound rule for 518 (ntalk). 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=518,ToPort=518,IpRanges="[{CidrIp=<source-cidr>}]"

Inbound UDP 518 (ntalk). Replace <source-cidr> (e.g. 10.0.0.0/16).

GCP firewall

gcloud compute firewall-rules create allow-ntalk-518 --direction=INGRESS --action=ALLOW --rules=udp:518 --source-ranges=<source-cidr> --network=<network>

Ingress rule for 518 (ntalk). Scope with --source-ranges and optionally --target-tags.

Windows netsh

netsh advfirewall firewall add rule name="Allow ntalk 518/UDP" dir=in action=allow protocol=UDP localport=518 remoteip=<source>

Inbound UDP 518 (ntalk). Set remoteip to a host/subnet; 'any' is discouraged.

Windows PowerShell

New-NetFirewallRule -DisplayName "Allow ntalk 518/UDP" -Direction Inbound -Action Allow -Protocol UDP -LocalPort 518 -RemoteAddress <source>

Inbound UDP 518 (ntalk). 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.