How to Install ClamAV on Ubuntu 20.04

Install ClamAV on Ubuntu 20.04

In this article, we will have explained the necessary steps to install and configure ClamAV on Ubuntu 20.04 LTS. Before continuing with this tutorial, make sure you are logged in as a user with sudo privileges. All the commands in this tutorial should be run as a non-root user.

ClamAV is an open-source Antivirus tool available for Linux distributions. It integrates Mail servers to scan attachments received. Other functions also include web scanning. ClamAV includes a multi-threaded scanner daemon, command-line utilities for on-demand file scanning and automatic signature updates. One of its main uses is on mail servers as a server-side email virus scanner.

Install ClamAV on Ubuntu 20.04

Step 1. First, before you start installing any package on your Ubuntu server, we always recommend making sure that all system packages are updated.

sudo apt update
sudo apt upgrade

Step 2. Install ClamAV on Ubuntu systems.

The default Ubuntu 20.04 repositories contain the latest stable release version of ClamAV. You can simply install it using the following command:

sudo apt install clamav clamav-daemon

Once, the packages are successfully installed, run the following command to check whether it has been installed or not:

clamscan --version

Step 3. Update the ClamAV Database.

First, stop the clamav-freshclam service (if it is running) and execute freshclam, the virus database update tool:

sudo systemctl stop clamav-freshclam

Then, update the virus database:

freshclam

Next, start the clamav-freshclam service and enable it to start at system reboot with the following command:

sudo systemctl start clamav-freshclam
sudo systemctl enable clamav-freshclam

Step 4. Use Clamscan to Scan.

The basic syntax of Clamscan is shown below:

clamscan [options] [files-or-directories]

You can print all available option with clamscan using the following command:

clamscan -h
Clam AntiVirus: Scanner 0.102.4
           By The ClamAV Team: https://www.clamav.net/about.html#credits
           (C) 2020 Cisco Systems, Inc.
 
    clamscan [options] [file/directory/-]
 
    --help                -h             Show this help
    --version             -V             Print version number
    --verbose             -v             Be verbose
    --archive-verbose     -a             Show filenames inside scanned archives
    --debug                              Enable libclamav's debug messages
    --quiet                              Only output error messages
    --stdout                             Write to stdout instead of stderr. Does not affect 'debug' messages.
    --no-summary                         Disable summary at end of scanning
    --infected            -i             Only print infected files
    --suppress-ok-results -o             Skip printing OK files
    --bell                               Sound bell on virus detection
 
    --tempdir=DIRECTORY                  Create temporary files in DIRECTORY
    --leave-temps[=yes/no(*)]            Do not remove temporary files
    --gen-json[=yes/no(*)]               Generate JSON description of scanned file(s). JSON will be printed and also-
                                         dropped to the temp directory if --leave-temps is enabled.
    --database=FILE/DIR   -d FILE/DIR    Load virus database from FILE or load all supported db files from DIR
    --official-db-only[=yes/no(*)]       Only load official signatures
    --log=FILE            -l FILE        Save scan report to FILE
    --recursive[=yes/no(*)]  -r          Scan subdirectories recursively
    --allmatch[=yes/no(*)]   -z          Continue scanning within file after finding a match
    --cross-fs[=yes(*)/no]               Scan files and directories on other filesystems
    --follow-dir-symlinks[=0/1(*)/2]     Follow directory symlinks (0 = never, 1 = direct, 2 = always)
    --follow-file-symlinks[=0/1(*)/2]    Follow file symlinks (0 = never, 1 = direct, 2 = always)
    --file-list=FILE      -f FILE        Scan files from FILE
    --remove[=yes/no(*)]                 Remove infected files. Be careful!
    --move=DIRECTORY                     Move infected files into DIRECTORY
    --copy=DIRECTORY                     Copy infected files into DIRECTORY
    --exclude=REGEX                      Don't scan file names matching REGEX
    --exclude-dir=REGEX                  Don't scan directories matching REGEX
    --include=REGEX                      Only scan file names matching REGEX
    --include-dir=REGEX                  Only scan directories matching REGEX
 
    --bytecode[=yes(*)/no]               Load bytecode from the database
    --bytecode-unsigned[=yes/no(*)]      Load unsigned bytecode
    --bytecode-timeout=N                 Set bytecode timeout (in milliseconds)
    --statistics[=none(*)/bytecode/pcre] Collect and print execution statistics
    --detect-pua[=yes/no(*)]             Detect Possibly Unwanted Applications
    --exclude-pua=CAT                    Skip PUA sigs of category CAT
    --include-pua=CAT                    Load PUA sigs of category CAT
    --detect-structured[=yes/no(*)]      Detect structured data (SSN, Credit Card)
    --structured-ssn-format=X            SSN format (0=normal,1=stripped,2=both)
    --structured-ssn-count=N             Min SSN count to generate a detect
    --structured-cc-count=N              Min CC count to generate a detect
    --scan-mail[=yes(*)/no]              Scan mail files
    --phishing-sigs[=yes(*)/no]          Enable email signature-based phishing detection
    --phishing-scan-urls[=yes(*)/no]     Enable URL signature-based phishing detection
    --heuristic-alerts[=yes(*)/no]       Heuristic alerts
    --heuristic-scan-precedence[=yes/no(*)] Stop scanning as soon as a heuristic match is found
    --normalize[=yes(*)/no]              Normalize html, script, and text files. Use normalize=no for yara compatibility
    --scan-pe[=yes(*)/no]                Scan PE files
    --scan-elf[=yes(*)/no]               Scan ELF files
    --scan-ole2[=yes(*)/no]              Scan OLE2 containers
    --scan-pdf[=yes(*)/no]               Scan PDF files
    --scan-swf[=yes(*)/no]               Scan SWF files
    --scan-html[=yes(*)/no]              Scan HTML files
    --scan-xmldocs[=yes(*)/no]           Scan xml-based document files
    --scan-hwp3[=yes(*)/no]              Scan HWP3 files
    --scan-archive[=yes(*)/no]           Scan archive files (supported by libclamav)
    --alert-broken[=yes/no(*)]           Alert on broken executable files (PE & ELF)
    --alert-encrypted[=yes/no(*)]        Alert on encrypted archives and documents
    --alert-encrypted-archive[=yes/no(*)] Alert on encrypted archives
    --alert-encrypted-doc[=yes/no(*)]    Alert on encrypted documents
    --alert-macros[=yes/no(*)]           Alert on OLE2 files containing VBA macros
    --alert-exceeds-max[=yes/no(*)]      Alert on files that exceed max file size, max scan size, or max recursion limit
    --alert-phishing-ssl[=yes/no(*)]     Alert on emails containing SSL mismatches in URLs
    --alert-phishing-cloak[=yes/no(*)]   Alert on emails containing cloaked URLs
    --alert-partition-intersection[=yes/no(*)] Alert on raw DMG image files containing partition intersections
    --nocerts                            Disable authenticode certificate chain verification in PE files
    --dumpcerts                          Dump authenticode certificate chain in PE files
 
    --max-scantime=#n                    Scan time longer than this will be skipped and assumed clean
    --max-filesize=#n                    Files larger than this will be skipped and assumed clean
    --max-scansize=#n                    The maximum amount of data to scan for each container file (**)
    --max-files=#n                       The maximum number of files to scan for each container file (**)
    --max-recursion=#n                   Maximum archive recursion level for container file (**)
    --max-dir-recursion=#n               Maximum directory recursion level
    --max-embeddedpe=#n                  Maximum size file to check for embedded PE
    --max-htmlnormalize=#n               Maximum size of HTML file to normalize
    --max-htmlnotags=#n                  Maximum size of normalized HTML file to scan
    --max-scriptnormalize=#n             Maximum size of script file to normalize
    --max-ziptypercg=#n                  Maximum size zip to type reanalyze
    --max-partitions=#n                  Maximum number of partitions in disk image to be scanned
    --max-iconspe=#n                     Maximum number of icons in PE file to be scanned
    --max-rechwp3=#n                     Maximum recursive calls to HWP3 parsing function
    --pcre-match-limit=#n                Maximum calls to the PCRE match function.
    --pcre-recmatch-limit=#n             Maximum recursive calls to the PCRE match function.
    --pcre-max-filesize=#n               Maximum size file to perform PCRE subsig matching.
    --disable-cache                      Disable caching and cache checks for hash sums of scanned files.

That’s all you need to do to installing ClamAV on Ubuntu 20.04 LTS Focal Fossa. I hope you find this quick tip helpful. For further reading on ClamAV, please refer to their official knowledge base. If you have questions or suggestions, feel free to leave a comment below.