Troubleshooting#

This page contains hints for troubleshooting general issues with the Greenbone Community Edition.

Facing an issue with the Greenbone Community Edition#

If you have an issue with the Greenbone Community Edition because something doesn’t work as expected and/or you are getting an error in the web UI it is necessary to check the log files to get some technical hints about the issue.

If something doesn’t work during the scan the /var/log/gvm/ospd-openvas.log and /var/log/gvm/openvas.log files should be checked for errors.

Otherwise the /var/log/gvm/gvmd.log file needs to be inspected.

Afterwards using the collected error messages in the search of our Community Forum may bring up possible results to resolve the issue already.

If no fitting results can be found feel free to create a new topic at our Community Forum. A post in the forum should always contain the installation method and the version of the Greenbone Community Edition (build from source via this guide, official community containers, Kali packages, …) and the found error message.

My scan does not show any results#

After a finished scan, your report does not contain any results or errors.

Some common issues if scans does not return any results are:

  1. The targets are not answering to an ICMP Echo Request → Check the Alive Test setting of your target definition and try some of the other available methods. Further reading:

  2. You are using a custom scan configuration which does not include the following two VTs from the Port scanners family.

    Further reading here

  3. You are using a port list which is not optimal for your environment:

    e.g., a All TCP and All UDP port list might be responsible for your port scan timing out, causing your scan to not return any results at all. It is suggested to start with a smaller port list, e.g., All IANA TCP.

  4. SELinux is enabled and blocking the scanner from doing its job.

  5. You do not have nmap installed or not available within your PATH.

For further debugging/logging, the mentioned Nmap (NASL wrapper) and Ping Host VTs allow to configure various settings:

  • Ping Host

    1. Report about unreachable Hosts configured to yes: include notes if a remote host is considered as dead/not reachable, and the reason why.

    2. Log failed nmap calls and Log nmap output configured to yes: Logs additional output if nmap was used.

  • Nmap (NASL wrapper)

    1. Log nmap output configured to yes: Log additional output if nmap was used.

OOM is killing Redis on large scans#

During a larger scan, the machine is running out of memory. Therefore, the Linux Out-of-Memory (OOM) killer is terminating the Redis database server and the scan gets interrupted.

The problem described is not easy to solve as it can have several root causes, from known issues to usage behavior. In particular, there can be problems with vHosts and CGI caching.

In general, we recommend the following:

  • Prevent overloading the system by adjusting the usage:

    • Do not start scan tasks all at once. Use schedules to start them at intervals.

    • Reconfigure scan targets to include less hosts. Split the hosts into more targets and tasks instead.

    • Do not run or schedule feed updates for times where scan tasks are running or scheduled to run.

    • Do not view or download large reports while scan tasks are running.

  • Disable vHost expansion for scans that cause problems:

    • Clone and edit the used scan configuration.

    • Set the scanner preference expand_vhosts to 0 and save the change.

  • Disable CGI caching for scans that cause problems:

    • Clone and edit the used scan configuration.

    • Navigate to the VT family Settings.

    • Edit the VT Global Variable Settings (OID: 1.3.6.1.4.1.25623.1.0.12288).

    • Set the preference Disable caching of web pages during CGI scanning to Yes and save the change.

If you think that you can narrow the problem down to a specific issue in the scanner please open an issue for the scanner at https://github.com/greenbone/openvas-scanner/issues.

For support on scan configuration changes like mentioned above to reduce the memory usage during a scan please open a topic at Scanning / scan configuration - Greenbone Community Forum.

Vulnerabilities are not found#

A scan report does not contain any results or some known vulnerabilities do not show up in the report.

This may have several reasons. Most likely, the feed synchronization is not finished yet. The feed data has been downloaded to the file system of the local machine but gvmd and ospd-openvas did not have enough resources to load them into their databases and memory yet. This can be checked on the web interface by opening the SecInfo > NVTs page to see whether VTs are listed there and the Administration > Feed Status page to see whether a synchronization process is currently running.

If both pages are fine, you may take a look at the following sections in our product manual: