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Sophos Firewall WAF Policy Crashing System

Hello Sophos Community

Using the latest firmware as of today (SFOS 19.5.0 GA-Build197) on Sophos Firewall, installed as a virtual appliance in Proxmox 7.3-4.  It's a home license, on 4 virtual CPUs (host), and 6GB memory.  I'm using the official qcow2 images.

I am hosting a Wordpress blog behind it, using WAF, which I use mainly for sharing family pictures and videos.  Below is a screenshot of the policy.

When this policy is applied to the firewall rule, everything works fine until I attempt to upload a very large file to the blog.  Recently, I attempted to upload our family's Christmas morning video to my site, which was 1.3GB.  Not only did it fail, but the entire firewall crashed... and crashed hard.  The house went offline, DNS resolution went down, I couldn't connect to the firewall via the IP address, nothing.  It just died.  I had to go into Proxmox, kill the VM, then restart it.  Upon restart everything was fine.

If I remove the WAF policy, the file uploads.  If I enable the WAF policy and transfer the file, everything comes crashing down.  It's a very easily reproduced.  What could be causing this?

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  • Hi,

    Deleted incorrect information.


    XG115W - v20.0.1 MR-1 - Home

    XG on VM 8 - v20 GA

    If a post solves your question please use the 'Verify Answer' button.

  • Basically the system should not crash based on a core dump of some kind of process. But in proxmox, do you have a console? Is there any kind of service still running? 


  • I believe the console itself was completely frozen too, but I'll need to test that to answer conclusively.  I can probably do that tomorrow.  Reproducing this tonight would impact the other WAF (wife acceptance factor).

  • Thanks for your reply.  I often upload family videos greater than 10MB, and have not seen this limit before.  Do you have a link I could check out?

  • If you can reproduce it, you could observe the memory footprint of the system to check, if the firewall is increasing. 


  • I'm going to reproduce this in the next hour or so.  Is memory footprint the only thing you'd like me to keep an eye on?  Should I watch anything else?

  • Alright, here's what I saw on this test:

    • File is a 1.3gb MP4 video.  Using Wordpress's built-in media uploading feature.
    • After about 1 minute all connections went down and the firewall froze.
    • Below I was able to capture "top" numbers in the firewall before the SSH session failed/froze
    • I saw a spike in Proxmox for the VM's memory and CPU... but they don't strike me as problematic.
    • The CPU spike did coincide with the firewall becoming unavailable.
    • After another minute or two, the firewall recovered itself and everything came back to life (except for the SSH session).
    • The firewall's downtime coincided with the CPU spike.
    • The transfer is hanging indefinitely, and presumably will eventually fail.

    NOTE: If not explicitly approved by Sophos support, any modifications
    top - 11:33:07 up 22:21,  2 users,  load average: 4.52, 1.14, 0.43
    Tasks: 464 total,   3 running, 459 sleeping,   0 stopped,   2 zombie
    %Cpu0  :  13.1/48.8   62[|||||||||||||||||||||||||||||||||||||                       ]     %Cpu1  :  17.3/56.5   74[||||||||||||||||||||||||||||||||||||||||||||                ]
    %Cpu2  :  15.2/67.3   82[|||||||||||||||||||||||||||||||||||||||||||||||||           ]     %Cpu3  :  19.4/46.7   66[||||||||||||||||||||||||||||||||||||||||                    ]
    GiB Mem : 99.8/5.8      [                                                            ]
    GiB Swap: 74.9/4.0      [   

  • Hello there,

    Thank you for contacting the Sophos Community.

    Did you try the suggestion Attila mentioned?

    What does the Sophos Firewall system graphs at around that time?

    Do you see anything under /var/cores?


    Emmanuel (EmmoSophos)
    Technical Team Lead, Global Community Support
    Sophos Support VideosProduct Documentation  |  @SophosSupport  | Sign up for SMS Alerts
    If a post solves your question use the 'Verify Answer' link.
  • I have not tried Attila's suggestion yet.  I work from home, so I can't be bringing my firewall down over and over :-).  I will report back when I know more, but on first glance, I'm not seeing an association between WebDAV and Wordpress for the media upload  capability.

    In the end it's less about the ability to upload the files, and more about the fact that the firewall crashes when I attempt to upload something which, perhaps, is unsupported.  A more graceful solution for that would definitely be appreciated... I could always upload stuff another way.  I'll report back as I learn more.

    As for /var/cores, I looked in there just now, during normal operation, and see nothing.

    SFVH_KV01_SFOS 19.5.0 GA-Build197# ls -l /var/cores
    SFVH_KV01_SFOS 19.5.0 GA-Build197#

    As for the Sophos Firewall system graphs, the test today was around 11:30.