Manage Telnet communications through the firewall IPD

To increase protection from network intrusions that can be caused by Telnet packets, you can configure the firewall IPD to drop all incoming packets that contain the Telnet protocol. This ensures that Telnet connections cannot get through the firewall IPD.

However, disabling Telnet prevents the use of one DeltaV diagnostic function. If Telnet is disabled, you may see a message similar to the following:

Could not open connection to the host. Connect failed

The message indicates that DeltaV is attempting and failing to determine network connectivity to the controller. You can use the Multicast Ping option to detect the controller. Alternatively, you can temporarily enable Telnet on the firewall IPD and then disable it again if necessary. Complete the following steps to disable Telnet.

Log on to the firewall IPD from the Management station.
1. Launch HiView (version 3.0 or later).
2. Enter the IP address of the firewall IPD in the URL field.
3. On the firewall IPD login screen, enter the administrator credentials.
  
  The default user name is Admin and the default password is Emerson1. However, this should have been changed when you initially configured the firewall IPD.
Expand Network Security in the hierarchy and select Packet Filter/Incoming Packets.
Scroll down through the Incoming IP Packets rules until you find the two rows that have Telnet in the Description column with the Source IP column showing a DeltaV primary IP address (10.4.0.0) and a DeltaV secondary IP address (10.8.0.0). The Destination Port is 23 for both.

Note that both Telnet rows initially show accept in the Action column.
Select drop in the Action column for each of the two Telnet rows.

There is a difference between drop and reject. Drop silently discards the incoming package. Reject results in an ICMP error or TCP Reset being returned.
Find the two rows labeled Diagnostics with a Destination Port of 18550.
Select drop in the Action column for each of the two Diagnostics rows.
Save this configuration.
1. Click the Set button at the bottom of this screen.
2. On the Load/Save screen, click New.
3. Enter no_telnet when prompted for a name.
4. Click OK.
The firewall IPD will now drop all incoming packets containing the Telnet protocol.
Save the running configuration to Non-volatile memory and AutoConfiguration Adapter by clicking the Save to NVM+ACA button at the bottom of the Load/Save screen.