Well-known · Cross-platform

102 ISO-TSAP / S7

TCP Yes
UDP Assigned
SCTP
DCCP

What it is

ISO Transport Service over TCP; also used by Siemens S7 industrial PLCs.

When / why

OT/ICS networks — Siemens S7 communications. Segment from IT networks.

Protocol status detail

TransportStatusMeaning
TCP Yes Assigned by IANA and standardized, specified, or widely used on this port.
UDP Assigned Assigned by IANA, but not 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 102

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 102

Allow TCP 102 (ISO-TSAP / S7). 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="102" protocol="tcp" accept'

Allow TCP 102 (ISO-TSAP / S7) from <source>. Run 'firewall-cmd --reload' afterwards.

nftables

nft add rule inet filter input ip saddr <source> tcp dport 102 accept

Allow TCP 102 (ISO-TSAP / S7). Assumes table 'inet filter' with an 'input' chain.

iptables

sudo iptables -A INPUT -p tcp -s <source> --dport 102 -j ACCEPT

Allow TCP 102 (ISO-TSAP / S7). Persist with iptables-save/netfilter-persistent.

Azure NSG

az network nsg rule create -g <resource-group> --nsg-name <nsg> -n Allow-isotsaps7-102 --priority 1000 --access Allow --direction Inbound --protocol TCP --source-address-prefixes <source> --destination-port-ranges 102

Inbound rule for 102 (ISO-TSAP / S7). 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=102,ToPort=102,IpRanges="[{CidrIp=<source-cidr>}]"

Inbound TCP 102 (ISO-TSAP / S7). Replace <source-cidr> (e.g. 10.0.0.0/16).

GCP firewall

gcloud compute firewall-rules create allow-isotsaps7-102 --direction=INGRESS --action=ALLOW --rules=tcp:102 --source-ranges=<source-cidr> --network=<network>

Ingress rule for 102 (ISO-TSAP / S7). Scope with --source-ranges and optionally --target-tags.

Windows netsh

netsh advfirewall firewall add rule name="Allow ISO-TSAP / S7 102/TCP" dir=in action=allow protocol=TCP localport=102 remoteip=<source>

Inbound TCP 102 (ISO-TSAP / S7). Set remoteip to a host/subnet; 'any' is discouraged.

Windows PowerShell

New-NetFirewallRule -DisplayName "Allow ISO-TSAP / S7 102/TCP" -Direction Inbound -Action Allow -Protocol TCP -LocalPort 102 -RemoteAddress <source>

Inbound TCP 102 (ISO-TSAP / S7). 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.