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.