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# Virus Scanner Support

## Overview

ClamAV is the only _officially_ supported virus scanner available for use with ownCloud. However, other anti-virus software can be used, so long as they:

- Can receive data streams via pipe on the command-line and return an exit code
- Return a parsable result, on stdout

### How ClamAV Works With ownCloud

Before you go about installing and configuring it, here is a bit of background which may be handy to know. ownCloud integrates with anti-virus tools by connecting to them via:

- A URL and port
- A socket
- Streaming the data from the command-line via a pipe with a configured executable

Files are checked when they are either uploaded or updated, whether that’s when they’re edited or saved, but not when they are downloaded.

The ownCloud Antivirus extension sends files as streams to a ClamAV service (which can be on the same ownCloud server or on another server within the same network) which in turn scans them and returns a scan result.

ownCloud evaluates either the exit code returned from ClamAV or parses the stdout response to retrieve the result of the scan. Based on ownCloud’s evaluation of the response, an appropriate response is then taken, such as recording a log message, or deleting the file.

Important

File Cache

ownCloud doesn’t support a file cache of previously scanned files.

## Configuring the ClamAV Antivirus Scanner

You can configure your ownCloud server to automatically run a virus scan on newly-uploaded files using the Antivirus App for Files. The Antivirus App for Files integrates the open source anti-virus engine ClamAV with ownCloud.

ClamAV detects all forms of malware including Trojan horses, viruses, and worms. What’s more, it operates on all the key operating systems, including Windows, Linux, and Mac files, and can scan compressed files, executables, image files, Flash, PDF, as well as many others.

ClamAV’s Freshclam daemon automatically updates its malware signature database at scheduled intervals. ClamAV runs on Linux and any Unix-type operating system, and Microsoft Windows. You must first install ClamAV, and then install and configure the Antivirus App for Files on ownCloud.

Important

Operating System Note

ownCloud has only been tested with ownCloud on Linux, so these instructions are for Linux systems.

## Installing ClamAV

As always, the various Linux distributions manage installing and configuring ClamAV in different ways.

### Debian, Ubuntu, Linux Mint

On Debian and Ubuntu systems, and their many variants, install ClamAV with these commands:

    apt-get install clamav clamav-daemon

The installer automatically creates default configuration files and launches the `clamd` and `freshclam` daemons. You don’t have to do anything more, though it’s a good idea to review the ClamAV documentation and your settings in `/etc/clamav/`. Enable verbose logging in both `clamd.conf` and `freshclam.conf` until you get any kinks worked out.

### Red Hat 7, CentOS 7

On Red Hat 7 and related systems, you must install the Extra Packages for Enterprise Linux (EPEL) repository, and then install ClamAV:

    yum install epel-release
    yum install clamav clamav-scanner clamav-scanner-systemd clamav-server
    clamav-server-systemd clamav-update

This installs two configuration files: `/etc/freshclam.conf` and `/etc/clamd.d/scan.conf`. You must edit both of these before you can run ClamAV. Both files are well-commented, and `man clamd.conf` and `man freshclam.conf` explain all the options. Refer to `/etc/passwd` and `/etc/group` when you need to verify the ClamAV user and group.

First, edit `/etc/freshclam.conf` and configure your options. `freshclam` updates your malware database, so you want it to run frequently to get updated malware signatures. Run it manually post-installation to download your first set of malware signatures:

    freshclam

The EPEL packages do not include an init file for `freshclam`, so the quick and easy way to set it up for regular checks is with a cron job. This example runs it every hour at 47 minutes past the hour:

    # m   h  dom mon dow  command
      47  *  *   *    *  /usr/bin/freshclam --quiet

Please avoid any multiples of 10, because those are when the ClamAV servers are hit the hardest for updates.

Next, edit `/etc/clamd.d/scan.conf`. When you’re finished you must enable the `clamd` service file and start `clamd`:

    systemctl enable clamav-daemon.service
    systemctl start clamav-daemon.service

That should take care of everything. Enable verbose logging in `scan.conf` and `freshclam.conf` until it is running the way you want.

## Enabling the Antivirus App for Files

To enable the Antivirus App for Files, go to your ownCloud Apps page to enable it.

## Configuring ClamAV on ownCloud

Next, go to your ownCloud Admin page and set your ownCloud logging level to Everything.

Now, find your Antivirus Configuration panel on your Admin page.

ClamAV runs in one of three modes:

Daemon (Socket)

In this mode, ClamAV runs in the background on the same server as the ownCloud installation. When there is no activity `clamd` places a minimal load on your system. However, if your users upload large volumes of files, you will see high CPU usage. So, please keep this in mind.

Daemon Via Host:Port

In this mode, ClamAV runs on a different server. This is a good option for ownCloud servers with high volumes of file uploads.

Executable

In this mode, ClamAV runs on the same server as the ownCloud installation, and the `clamscan` command only runs when a file is uploaded. `clamscan` is slow and not always reliable for on-demand usage; it is better to use one of the daemon modes.

### Daemon (Socket)

ownCloud should detect your `clamd` socket and fill in the `Socket` field. This is the `LocalSocket` option in `clamd.conf`. You can run `netstat` to verify:

     netstat -a|grep clam
     unix 2 [ ACC ] STREAM LISTENING 15857 /var/run/clamav/clamd.ctl

    .. figure:: ../images/antivirus-daemon-socket.png

The `Stream Length` value sets the number of bytes read in one pass. 10485760 bytes, or ten megabytes, is the default. This value should be no larger than the PHP `memory_limit` settings, or physical memory if `memory_limit` is set to -1 (no limit).

`Action for infected files found while scanning` gives you the choice of logging any alerts without deleting the files, or immediately deleting infected files.

### Daemon

For the Daemon option, you need the hostname or IP address of the remote server running ClamAV and the server’s port number.

### Executable

The Executable option requires the path to `clamscan`, which is the interactive ClamAV scanning command. ownCloud should find it automatically.

When you are satisfied with how ClamAV is operating, you might want to go back and change all of your logging to less verbose levels.

### Rule Configuration

ownCloud provides the ability to customize how ownCloud reacts to the response provided by an anti-virus scan. To do so, under `Admin -> Antivirus Configuration -> Advanced`, which you can see in the screenshot below, you can view and change the existing rules. You can also add new ones.

Rules can match on either an exit status (e.g., 0, 1, or 40) or a pattern in the string returned from ClamAV (e.g., `/.*: (.*) FOUND$/`).

#### Update An Existing Rule

To match on an exit status, change the “Match by” dropdown list to “Scanner exit status” and in the “Scanner exit status or signature to search” field, add the status code to match on.

To match on the scanner’s output, change the “Match by” dropdown list to “Scanner output” and in the “Scanner exit status or signature to search” field, add the regular expression to match against the scanner’s output.

Then, while not mandatory, add a description of what the status or scan output means. After that, set what ownCloud should do when the exit status or regular expression you set matches the value returned by ClamAV. To do so change the value of the dropdown in the “Mark as” column.

The dropdown supports the following three options:

Option | Description
--- | ---
Clean | The file is clean, and contains no viruses
Infected | The file contains a virus
Unchecked | No action should be taken

With all these changes made, click the check mark on the left-hand side of the “Match by” column, to confirm the change to the rule.

#### Add A New Rule

To add a new rule, click the button marked “Add a rule” at the bottom left of the rules table. Then follow the process outlined in Update An Existing Rule.

#### Delete An Existing Rule

To delete an existing rule, click the rubbish bin icon on the far right-hand side of the rule that you want to delete.

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