• 1.  Juniper SRX - OPC Communication Flow Stops

    Posted 09-11-2021 12:45


    We have Juniper SRX300 in our network. As per the scenario, two servers are there that are sharing the data using OPC communication through the Juniper SRX. Server-A gets data from Server-B as per the scheduled time. The configured schedule in the application on Server-A is 6 hours, so every 6 hours Server-A tries to fetch the latest data from Server-B. The issue is Server-A is only able to get the limited data sometimes its 40 %, sometimes its 30%, sometimes its 60% and other values end in error. When I physically bypass the firewall and connect the servers through a switch only, the data fetching works perfectly fine. 
    I have checked the logs for any blocked traffic, and have also monitored and reviewed the traceoption logs during the scheduled time interval for the data fetching. Also, IDP is not enabled. 
    I have tried the below mentioned: 

    1) Allow all communication between Server-A & Server-B (Considering that after some interval, application may be using some other port for reverification) 
    2) Globally allowing all the communication (There may be some other communication involved)
    3) Changed the traffic between Server-A to Server-B to packet-mode. 

    Still the issue remains the same. I have done this troubleshooting, still I am unable to figure what may be the probable cause that causing this data flow to stop.  I have attached the scenario block diagram for reference. 

    Really needs the expert opinion on this as I am exhausted with the resources and knowledge I had to troubleshoot the issue. 


  • 2.  RE: Juniper SRX - OPC Communication Flow Stops

    Posted 09-11-2021 13:18

    Thank you for posting this question! Ask the Expert is not monitored except during live Ask the Experts sessions.

    Please post your question to the Security community and someone will answer it!​ I did mention your post in a discussion forum there to help.

    Thank you!

    Ellen MacDermid