# Signature Testing and Management --- <!-- TOC depthFrom:2 depthTo:6 withLinks:1 updateOnSave:1 orderedList:0 --> - [freshclam](#freshclam) - [sigtool](#sigtool) - [clambc](#clambc) <!-- /TOC --> --- ## freshclam --- The tool `freshclam` is used to download and update ClamAV’s official virus signature databases. While easy to use in its base configuration, `freshclam` does require a working [`freshclam.conf` configuration file](Configuration.md#freshclam) to run (the location of which can be passed in via command line if the default search location does not fit your needs). Once you have a valid configuration file, you can invoke freshclam with the following command: > $ freshclam By default, `freshclam` will then attempt to connect to ClamAV's virus signature database distribution network. If no databases exist in the directory specified, `freshclam` will do a fresh download of the requested databases. Otherwise, `freshclam` will attempt to update existing databases, pairing them against downloaded cdiffs. If a database is found to be corrupted, it is not updated and instead replaced with a fresh download. Of course, all this behaviour--and more--can be changed to suit your needs by [modifying `freshclam.conf` and/or using various command line options](Configuration.md#freshclamconf). You can find more information about freshclam with the commands: > $ man freshclam and > $ freshclam --help --- ## sigtool --- ClamAV provides `sigtool` as a command-line testing tool for assisting users in their efforts creating and working with virus signatures. While sigtool has many uses--including crafting signatures--of particular note, is sigtool's ability to help users and analysts in determining if a file detected by *libclamav*'s virus signatures is a false positive. This can be accomplished by using the command: > $ sigtool --unpack=FILE Where FILE points to your virus signature databases. Then, once `sigtool` has finished unpacking the database into the directory from which you ran the command, you can search for the offending signature name (provided either by [`clamscan`](./Scanning.md#clamscan) scan reports or [`clamd`](./Scanning.md#clamd) logs). As an example: > $ grep "Win.Test.EICAR" ./* Or, do all that in one step with: > $ sigtool --find="Win.Test.EICAR" This should give you the offending signature(s) in question, which can then be included as part of your [false positive report](https://www.clamav.net/reports/fp). To learn more in depth information on how `sigtool` can be used to help create virus signatures and work with malicious (and non-malicious) files please reference the many online tutorials on the topic. Otherwise, information on available sigtool functions can be easily referenced with: > $ sigtool --help and > $ man sigtool --- ## clambc --- `clambc` is Clam Anti-Virus’ bytecode signature testing tool. It can be used to test newly crafted bytecode signatures or to help verify existing bytecode is executing against a sample as expected. For more detailed help, please use: > $ man clambc or > $ clambc --help