Sophos Firewall: Troubleshooting 0 Byte SSL VPN File

Disclaimer: This information is provided as-is for the benefit of the Community. Please contact Sophos Professional Services if you require assistance with your specific environment.


Overview

This Recommended read describes a certain user situation and troubleshooting suggestions if the SSL VPN Client download may incorrectly be presented as a 0-byte download from the User Portal.

Ensure the default/custom CA details are properly configured

  • Is a custom CA being used?
    • If so, does the issue occur if the default self-signed certificate is used instead?

If using the default self-signed certificate resolves the issue, please verify the custom CA is properly assembled (proper signing CA, etc.)

User Certificate Generation is failing

To regenerate an individual user's SSL VPN certificate, you’ll have to go to the Sophos Firewall GUI and delete their user certificate (Certificates > Certificates)

    • Their user certificate will be regenerated the next time they sign into the Sophos Firewall User Portal and download their SSL VPN Configuration.

If you are still experiencing issues, you can regenerate the Default CA by navigating to Certificates > Certificate Authorities.
This will force the regeneration of all SSL VPN user certificates and restart the SSL VPN service.

If these actions are performed, affected users must re-download their SSL VPN installation file to utilize the new certificate.

Check the /tmp partition on the device

Navigate to the /tmp partition and investigate if the following SSL VPN files are present

  • # cd tmp
  • # cd /content/sslvpn
  • # ls
    • Confirm if the following SSL VPN files are present in /content/sslvpn:
    • rw-rr- 1 1000 100 413 Apr 24 2015 client-config-template.ovpn
    • rw-rr- 1 1000 100 111.1K Jun 17 19:35 ssl-vpn-config-installer.exe
    • rw-rr- 1 1000 100 1.4M Jun 17 19:35 ssl-vpn-client-installer.exe
    • rw-rr- 1 1000 100 72 Jun 17 19:49 U2DVERSION

If files aren’t present, try to manually update patterns for the SSL VPN Module

  • If patterns fail to update, don't hesitate to get in touch with Sophos Support

Check if the /tmp partition is full

  • # df –h

    • If full, please contact Sophos Support for further assistance.

Update the device’s patterns

  • Try performing a manual pattern update
  • Backup & firmware > Pattern Updates > “Update Pattern”
  • If patterns fail to update, please contact Sophos Support



Revamped RR Removed XG Corrected Grammar, spacing and formatting
[edited by: Erick Jan at 1:11 AM (GMT -8) on 23 Nov 2023]
Parents
  • Hello,

    Thank you for the guide. It pointed me good direction. In my case, the problem was, that the symbolic link /content/sslvpn was broken. It was pointing to not existing directory /content/sslvpn_1.01/0 and it was supposed to point to /content/sslvpn_1.01/1.0.008/

    Commands to check the symbolic link and fix the issue in Advanced shell:

    Directories with installed Patterns:

    SG310_WP01_SFOS 17.5.14 MR-14-1# ls -ald /content/sslvpn_*/*
    drwxr-xr-x    2 root     0             1024 Jan  2  2020 /content/sslvpn_1.00/1.0.007
    drwxr-xr-x    2 root     0             1024 Nov 26 10:27 /content/sslvpn_1.01/1.0.008
    

    Get where symbolic is pointing if it exists. It should point to one of the directories with installed Patterns, so:

    SG310_WP01_SFOS 17.5.14 MR-14-1# ls -altr /content/sslvpn
    lrwxrwxrwx    1 root     0               29 Nov 26 10:27 /content/sslvpn -> /content/sslvpn_1.01/1.0.008/
    

    In my case, the symbolic link existed, but was not correct:

    SG310_WP01_SFOS 17.5.14 MR-14-1# ls -altr /content/sslvpn
    lrwxrwxrwx    1 root     0               22 Sep 10 20:48 sslvpn -> /content/sslvpn_1.01/0

    To fix this situation, I deleted old symbolic link and created new one:

    SG310_WP01_SFOS 17.5.14 MR-14-1# cd /content/
    SG310_WP01_SFOS 17.5.14 MR-14-1# rm sslvpn
    SG310_WP01_SFOS 17.5.14 MR-14-1# ln -s /content/sslvpn_1.01/1.0.008/ sslvpn

    BTW: The problem with 0Byte SSL VPN File was noticed after switching Cluster from Primary to Auxiliary appliance. The symbolic link was broken just on the appliance that was Auxiliary during Pattern update.     

    I hope this will help to someone.

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