Difference between revisions of "ClamAV"

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[[Category:Daemons and system services]]
 
 
[[Category:Security]]
 
[[Category:Security]]
 
[[es:ClamAV]]
 
[[es:ClamAV]]
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[[fr:CLAMAV]]
 
[[it:ClamAV]]
 
[[it:ClamAV]]
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[[ja:ClamAV]]
 
[[ru:ClamAV]]
 
[[ru:ClamAV]]
 
[[sr:ClamAV]]
 
[[sr:ClamAV]]
 
[[zh-CN:ClamAV]]
 
[[zh-CN:ClamAV]]
[http://www.clamav.net Clam AntiVirus] is an open source (GPL) anti-virus toolkit for UNIX.  It provides a number of utilities including a flexible and scalable multi-threaded daemon, a command line scanner and advanced tool for automatic database updates. Because ClamAV's main use is on file/mail servers for Windows desktops it primarily detects Windows viruses and malware.
+
[http://www.clamav.net Clam AntiVirus] is an open source (GPL) anti-virus toolkit for UNIX.  It provides a number of utilities including a flexible and scalable multi-threaded daemon, a command line scanner and advanced tool for automatic database updates. Because ClamAV's main use is on file/mail servers for Windows desktops it primarily detects Windows viruses and malware.
  
 
== Installation ==
 
== Installation ==
ClamAV can be [[pacman|installed]] with package {{Pkg|clamav}}, available in the [[Official Repositories]].
 
  
== Configuration ==
+
ClamAV can be [[install]]ed with package {{Pkg|clamav}}.
Whether you are going to use clamav as a daemon or use it as a simple file checker you need to comment out the line that contains the word ''Example'', usually it is found at the beginning of {{ic|/etc/clamav/freshclam.conf}} and {{ic|/etc/clamav/clamd.conf}} files.
+
 
+
== Starting the daemon ==
+
To start the daemon:
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# systemctl start clamd
+
 
+
To start it automatically at boot:
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# systemctl enable clamd
+
 
+
Also in {{ic|/etc/conf.d/clamav}} change the start options from "no" to "yes".
+
 
+
# change these to "yes" to start
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START_FRESHCLAM="yes"
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START_CLAMD="yes"
+
  
 
== Updating database ==
 
== Updating database ==
Edit the below file and comment out the line saying "Example"
 
# vim /etc/clamav/freshclam.conf
 
  # Comment or remove the line below.
 
  #Example
 
 
 
Update the virus definitions with:
 
Update the virus definitions with:
 
  # freshclam
 
  # freshclam
Line 39: Line 20:
 
  /var/lib/clamav/daily.cvd
 
  /var/lib/clamav/daily.cvd
 
  /var/lib/clamav/main.cvd
 
  /var/lib/clamav/main.cvd
 +
/var/lib/clamav/bytecode.cvd
 +
 +
The virus definition updater service is called {{ic|freshclamd.service}}. Consider starting it and enabling it to start at boot so that the virus definitions are kept recent.
 +
 +
== Starting the daemon ==
 +
 +
Consider updating the database before starting the service for the first time or you will run into troubles/errors which will prevent ClamAV to start correctly.
 +
 +
The service is called {{ic|clamd.service}}. Read [[Daemons]] for more information about starting it and enabling it to start at boot. You will need to run {{ic|freshclam}} prior to starting the service.
 +
 +
== Testing the software ==
 +
 +
In order to make sure ClamAV and the definitions are installed correctly, scan the [http://www.eicar.org/86-0-Intended-use.html EICAR test file] (a harmless signature with no virus code) with clamscan.
 +
 +
$ wget -O- http://www.eicar.org/download/eicar.com.txt | clamscan -
 +
 +
The output '''must''' include:
 +
 +
stdin: Eicar-Test-Signature FOUND
 +
 +
Otherwise; read the Troubleshooting part or ask for help in the [https://bbs.archlinux.org/ Arch Forums].
 +
 +
== Adding more databases/signatures repositories ==
 +
 +
ClamAV can use databases/signature from other repositories or security vendors.
 +
 +
To add the most important ones in a single step install {{AUR|clamav-unofficial-sigs}} and configure it in {{ic|/etc/clamav-unofficial-sigs/user.conf}}.
 +
 +
This will add signatures/databases from e.g. MalwarePatrol, SecuriteInfo, Yara, Linux Malware Detect,...
 +
 +
== Scan for viruses ==
  
== Scan for Viruses ==
 
 
{{ic|clamscan}} can be used to scan certain files, home directory, or an entire system:
 
{{ic|clamscan}} can be used to scan certain files, home directory, or an entire system:
  
 
  $ clamscan myfile
 
  $ clamscan myfile
  $ clamscan -r -i /home
+
  $ clamscan --recursive=yes --infected /home # or -r -i
  $ clamscan -r -i --exclude-dir=^/sys\|^/proc\|^/dev /
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  $ clamscan --recursive=yes --infected --exclude-dir='^/sys|^/proc|^/dev|^/lib|^/bin|^/sbin' /
  
If you would like {{ic|clamscan}} to remove the infected file use the {{ic|--remove}} option in the command.
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If you would like {{ic|clamscan}} to remove the infected file add to the command the {{ic|--remove}} option, or you can use {{ic|1=--move=/dir}} to quarantine them.
 +
 
 +
Using the {{ic|1=-l /path/to/file}} option will print the {{ic|clamscan}} logs to a text  file for locating reported infections.
 +
 
 +
== Using the milter ==
 +
 
 +
Copy {{ic|/etc/clamav/clamav-milter.conf.sample}} to {{ic|/etc/clamav/clamav-milter.conf}} and adjust it to your needs. For example:
 +
 +
{{hc|/etc/clamav/clamav-milter.conf|2=<nowiki>
 +
MilterSocket /run/clamav/clamav-milter.sock
 +
MilterSocketMode 660
 +
FixStaleSocket yes
 +
User clamav
 +
PidFile /run/clamav/clamav-milter.pid
 +
TemporaryDirectory /tmp
 +
ClamdSocket unix:/var/lib/clamav/clamd.sock
 +
LogSyslog yes
 +
LogInfected Basic
 +
</nowiki>}}
 +
 
 +
Create {{ic|/etc/systemd/system/clamav-milter.service}}:
 +
 
 +
{{hc|/etc/systemd/system/clamav-milter.service|2=<nowiki>
 +
[Unit]
 +
Description='ClamAV Milter'
 +
After=clamd.service
 +
 
 +
[Service]
 +
Type=forking
 +
ExecStart=/usr/bin/clamav-milter --config-file /etc/clamav/clamav-milter.conf
 +
 
 +
[Install]
 +
WantedBy=multi-user.target
 +
</nowiki>}}
 +
 
 +
Enable and start the service.
  
 
== Troubleshooting ==
 
== Troubleshooting ==
 +
 +
=== Error: Clamd was NOT notified ===
 +
 
If you get the following messages after running freshclam:
 
If you get the following messages after running freshclam:
WARNING: Clamd was NOT notified: Cannot connect to clamd through  
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{{bc|
/var/lib/clamav/clamd.sock connect(): No such file or directory
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WARNING: Clamd was NOT notified: Cannot connect to clamd through  
 +
/var/lib/clamav/clamd.sock connect(): No such file or directory
 +
}}
  
Add a sock file for clamav:
+
Add a sock file for ClamAV:
# touch /var/lib/clamav/clamd.sock
+
{{bc|
# chown clamav:clamav /var/lib/clamav/clamd.sock
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# touch /var/lib/clamav/clamd.sock
Then, edit {{Ic|/etc/clamav/clamd.conf}} &ndash; uncomment this line:
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# chown clamav:clamav /var/lib/clamav/clamd.sock
 +
}}
 +
Then, edit {{Ic|/etc/clamav/clamd.conf}} - uncomment this line:
 
  LocalSocket /var/lib/clamav/clamd.sock
 
  LocalSocket /var/lib/clamav/clamd.sock
Save the file and restart the daemon {{ic|systemctl restart clamd}}
+
Save the file and [[Daemons|restart the daemon]]
 +
 
 +
=== Error: No supported database files found ===
  
 
If you get the next error when starting the daemon:
 
If you get the next error when starting the daemon:
LibClamAV Error: cli_loaddb(): No supported database files found
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{{bc|
in /var/lib/clamav ERROR: Not supported data format
+
LibClamAV Error: cli_loaddb(): No supported database files found
 +
in /var/lib/clamav ERROR: Not supported data format
 +
}}
 
   
 
   
Run freshclam as root:
+
This happens because of mismatch between {{ic|/etc/freshclam.conf}} setting {{ic|DatabaseDirectory}} and {{ic|/etc/clamd.conf}} setting {{ic|DatabaseDirectory}}.
# freshclam -v
+
{{ic|/etc/freshclam.conf}} pointing to {{ic|/var/lib/clamav}}, but {{ic|/etc/clamd.conf}} (default directory) pointing to {{ic|/usr/share/clamav}}, or other directory. Edit in {{ic|/etc/clamd.conf}} and replace with the same DatabaseDirectory like in {{ic|/etc/freshclam.conf}}. After that clamav will start up succesfully.
  
If you get a:
+
=== Error: Can't create temporary directory ===
# can't create temporary directory
+
error,
+
along with a 'HINT' containing a UID and a GID number.
+
  
Do the following:
+
If you get the following error, along with a 'HINT' containing a UID and a GID number:
  # chown UID:GID /var/lib/clamav & chmod 755 /var/lib/clamav
+
  # can't create temporary directory
  
  # ex: chown 64:64
+
Correct permissions:
 +
  # chown UID:GID /var/lib/clamav & chmod 755 /var/lib/clamav

Latest revision as of 19:34, 16 May 2016

Clam AntiVirus is an open source (GPL) anti-virus toolkit for UNIX. It provides a number of utilities including a flexible and scalable multi-threaded daemon, a command line scanner and advanced tool for automatic database updates. Because ClamAV's main use is on file/mail servers for Windows desktops it primarily detects Windows viruses and malware.

Installation

ClamAV can be installed with package clamav.

Updating database

Update the virus definitions with:

# freshclam

The database files are saved in:

/var/lib/clamav/daily.cvd
/var/lib/clamav/main.cvd
/var/lib/clamav/bytecode.cvd

The virus definition updater service is called freshclamd.service. Consider starting it and enabling it to start at boot so that the virus definitions are kept recent.

Starting the daemon

Consider updating the database before starting the service for the first time or you will run into troubles/errors which will prevent ClamAV to start correctly.

The service is called clamd.service. Read Daemons for more information about starting it and enabling it to start at boot. You will need to run freshclam prior to starting the service.

Testing the software

In order to make sure ClamAV and the definitions are installed correctly, scan the EICAR test file (a harmless signature with no virus code) with clamscan.

$ wget -O- http://www.eicar.org/download/eicar.com.txt | clamscan -

The output must include:

stdin: Eicar-Test-Signature FOUND

Otherwise; read the Troubleshooting part or ask for help in the Arch Forums.

Adding more databases/signatures repositories

ClamAV can use databases/signature from other repositories or security vendors.

To add the most important ones in a single step install clamav-unofficial-sigsAUR and configure it in /etc/clamav-unofficial-sigs/user.conf.

This will add signatures/databases from e.g. MalwarePatrol, SecuriteInfo, Yara, Linux Malware Detect,...

Scan for viruses

clamscan can be used to scan certain files, home directory, or an entire system:

$ clamscan myfile
$ clamscan --recursive=yes --infected /home # or -r -i
$ clamscan --recursive=yes --infected --exclude-dir='^/sys|^/proc|^/dev|^/lib|^/bin|^/sbin' /

If you would like clamscan to remove the infected file add to the command the --remove option, or you can use --move=/dir to quarantine them.

Using the -l /path/to/file option will print the clamscan logs to a text file for locating reported infections.

Using the milter

Copy /etc/clamav/clamav-milter.conf.sample to /etc/clamav/clamav-milter.conf and adjust it to your needs. For example:

/etc/clamav/clamav-milter.conf
MilterSocket /run/clamav/clamav-milter.sock
MilterSocketMode 660
FixStaleSocket yes
User clamav
PidFile /run/clamav/clamav-milter.pid
TemporaryDirectory /tmp
ClamdSocket unix:/var/lib/clamav/clamd.sock
LogSyslog yes
LogInfected Basic

Create /etc/systemd/system/clamav-milter.service:

/etc/systemd/system/clamav-milter.service
[Unit]
Description='ClamAV Milter'
After=clamd.service

[Service]
Type=forking
ExecStart=/usr/bin/clamav-milter --config-file /etc/clamav/clamav-milter.conf

[Install]
WantedBy=multi-user.target

Enable and start the service.

Troubleshooting

Error: Clamd was NOT notified

If you get the following messages after running freshclam:

WARNING: Clamd was NOT notified: Cannot connect to clamd through 
/var/lib/clamav/clamd.sock connect(): No such file or directory

Add a sock file for ClamAV:

# touch /var/lib/clamav/clamd.sock
# chown clamav:clamav /var/lib/clamav/clamd.sock

Then, edit /etc/clamav/clamd.conf - uncomment this line:

LocalSocket /var/lib/clamav/clamd.sock

Save the file and restart the daemon

Error: No supported database files found

If you get the next error when starting the daemon:

LibClamAV Error: cli_loaddb(): No supported database files found
in /var/lib/clamav ERROR: Not supported data format

This happens because of mismatch between /etc/freshclam.conf setting DatabaseDirectory and /etc/clamd.conf setting DatabaseDirectory. /etc/freshclam.conf pointing to /var/lib/clamav, but /etc/clamd.conf (default directory) pointing to /usr/share/clamav, or other directory. Edit in /etc/clamd.conf and replace with the same DatabaseDirectory like in /etc/freshclam.conf. After that clamav will start up succesfully.

Error: Can't create temporary directory

If you get the following error, along with a 'HINT' containing a UID and a GID number:

# can't create temporary directory

Correct permissions:

# chown UID:GID /var/lib/clamav & chmod 755 /var/lib/clamav