Siemens Simatic S7-300 - Page 45

Configuration and operation
6.1 Security recommendations
CP 343-1 Lean
Equipment Manual, 01/2023, C79000−G8976−C198−09
45
• Default of the port
– Open
The port is open at the start of the configuration.
– Closed
The port is closed at the start of the configuration.
• Port status
– Open
The port is always open and cannot be closed.
– Open after configuration
The port is open if it has been configured.
– Open (login, when configured)
As default the port is open. After configuring the port, the communications partner
needs to log in.
– Open with block call
The port is only opened when a suitable program block is called.
• Authentication
Specifies whether or not the protocol authenticates the communications partner during
access.
Protocol /
function
Port number
(protocol)
Default of the
port
Port status Authentication
S7 and online
connections
102 (TCP)
Open
Open after configuration
No
HTTP
80 (TCP)
Closed
Open after configuration
No
SNMP
161 (UDP)
Open
Open after configuration
Yes (with SNMPv3)
Ports of communication partners and routers
Make sure that you enable the required client ports in the corresponding firewall on the
communications partners and in intermediary routers.
These can be:
• NTP / 123 (UDP)
• DNS / 53 (UDP)
• DHCP / 67, 68 (UDP)