Registered · Cross-platform

23399 Skype

TCP Unofficial
UDP
SCTP
DCCP

What it is

Skype default protocol port.

When / why

VoIP/IM client.

Protocol status detail

TransportStatusMeaning
TCP Unofficial Not assigned by IANA, but 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 23399

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 23399

Allow TCP 23399 (Skype). 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="23399" protocol="tcp" accept'

Allow TCP 23399 (Skype) from <source>. Run 'firewall-cmd --reload' afterwards.

nftables

nft add rule inet filter input ip saddr <source> tcp dport 23399 accept

Allow TCP 23399 (Skype). Assumes table 'inet filter' with an 'input' chain.

iptables

sudo iptables -A INPUT -p tcp -s <source> --dport 23399 -j ACCEPT

Allow TCP 23399 (Skype). Persist with iptables-save/netfilter-persistent.

Azure NSG

az network nsg rule create -g <resource-group> --nsg-name <nsg> -n Allow-skype-23399 --priority 1000 --access Allow --direction Inbound --protocol TCP --source-address-prefixes <source> --destination-port-ranges 23399

Inbound rule for 23399 (Skype). 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=23399,ToPort=23399,IpRanges="[{CidrIp=<source-cidr>}]"

Inbound TCP 23399 (Skype). Replace <source-cidr> (e.g. 10.0.0.0/16).

GCP firewall

gcloud compute firewall-rules create allow-skype-23399 --direction=INGRESS --action=ALLOW --rules=tcp:23399 --source-ranges=<source-cidr> --network=<network>

Ingress rule for 23399 (Skype). Scope with --source-ranges and optionally --target-tags.

Windows netsh

netsh advfirewall firewall add rule name="Allow Skype 23399/TCP" dir=in action=allow protocol=TCP localport=23399 remoteip=<source>

Inbound TCP 23399 (Skype). Set remoteip to a host/subnet; 'any' is discouraged.

Windows PowerShell

New-NetFirewallRule -DisplayName "Allow Skype 23399/TCP" -Direction Inbound -Action Allow -Protocol TCP -LocalPort 23399 -RemoteAddress <source>

Inbound TCP 23399 (Skype). 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.