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

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:

    • 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 host and/or vulnerability test, please either open an issue for the scanner at or the vulnerability test at Vulnerability Tests - 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: