The following information describes . A firewall is a gateway that controls access to your network. To restrict access to your Ethernet controller and I/O network, you may want to consider a firewall.
There are network-level and application-level firewalls:
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Network-level firewalls: These firewalls are frequently installed between the Internet and a single point of entry to an internal, protected network.
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Application-level firewalls: An application-level firewall acts on behalf of an application. It intercepts all traffic destined for that application and decides whether to forward that traffic to the application. Application-level firewalls reside on individual host computers.
The following table contains the port numbers used by NOE:
|
Protocol
|
Port Number
|
|
Modbus/TCP
|
TCP 502
|
|
HTTP
|
TCP 80
|
|
SNMP
|
UDP 61
|
|
FTP
|
TCP 21
|
You may need to provide the information in this table to your system administrator so that the firewall configuration will allow access to your PLC from outside of your facility.
