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clamav antivirus + milter 구성

2009.05.12 22:58

HOSTWAY 조회 수:23443

clamav antivirus + milter 구성


    clamav 는 Open-Source antivirus 솔루션이며, 방대하게 이용되고 있다.
    clamav 는 CORE 엔진이며, clamav-milter 는 sendmail MTA 로 전송되는 메일의 구문이나, 첨부 파일에서 바이러스 패턴을 검색하는 역할을 한다.
    CentOS, Fedora 등의 배포본을 이용한다면, yum -y install clamav* 와 같이 간단히 설치 및 구동이 가능하나,
    본 페이지에서는 배포되는 소스를 이용하여, clamav-0.94.2 버전을 설치를 해보겠다.

1. 패키지 다운로드 및 컴파일
    [root@localhost root]# ./configure --prefix=/usr/local/clamav --enable-milter
    [root@localhost root]# make && make install
    와 같이 /usr/local/clamav 에 컴파일이 완료되었다.

2. clamav 환경 설정; 라인이 길므로 아래와 동일하게 /usr/local/clamav/etc/ 폴더에 각각의 파일을 생성한다.
[root@localhost root]# cat /usr/local/clamav/etc/clamd.conf
##
## Example config file for the Clam AV daemon
## Please read the clamd.conf(5) manual before editing this file.
##


# Comment or remove the line below.
#Example

# Uncomment this option to enable logging.
# LogFile must be writable for the user running daemon.
# A full path is required.
# Default: disabled
LogFile /tmp/clamd.log

# By default the log file is locked for writing - the lock protects against
# running clamd multiple times (if want to run another clamd, please
# copy the configuration file, change the LogFile variable, and run
# the daemon with --config-file option).
# This option disables log file locking.
# Default: no
#LogFileUnlock yes

# Maximum size of the log file.
# Value of 0 disables the limit.
# You may use 'M' or 'm' for megabytes (1M = 1m = 1048576 bytes)
# and 'K' or 'k' for kilobytes (1K = 1k = 1024 bytes). To specify the size
# in bytes just don't use modifiers.
# Default: 1M
#LogFileMaxSize 2M

# Log time with each message.
# Default: no
LogTime yes

# Also log clean files. Useful in debugging but drastically increases the
# log size.
# Default: no
LogClean yes

# Use system logger (can work together with LogFile).
# Default: no
#LogSyslog yes

# Specify the type of syslog messages - please refer to 'man syslog'
# for facility names.
# Default: LOG_LOCAL6
#LogFacility LOG_MAIL

# Enable verbose logging.
# Default: no
#LogVerbose yes

# This option allows you to save a process identifier of the listening
# daemon (main thread).
# Default: disabled
#PidFile /var/run/clamd.pid

# Optional path to the global temporary directory.
# Default: system specific (usually /tmp or /var/tmp).
#TemporaryDirectory /var/tmp

# Path to the database directory.
# Default: hardcoded (depends on installation options)
DatabaseDirectory /usr/local/clamav

# The daemon can work in local mode, network mode or both.
# Due to security reasons we recommend the local mode.

# Path to a local socket file the daemon will listen on.
# Default: disabled (must be specified by a user)
LocalSocket /tmp/clamd.socket

# Remove stale socket after unclean shutdown.
# Default: yes
#FixStaleSocket yes

# TCP port address.
# Default: no
#TCPSocket 3310

# TCP address.
# By default we bind to INADDR_ANY, probably not wise.
# Enable the following to provide some degree of protection
# from the outside world.
# Default: no
#TCPAddr 127.0.0.1

# Maximum length the queue of pending connections may grow to.
# Default: 15
#MaxConnectionQueueLength 30

# Clamd uses FTP-like protocol to receive data from remote clients.
# If you are using clamav-milter to balance load between remote clamd daemons
# on firewall servers you may need to tune the options below.

# Close the connection when the data size limit is exceeded.
# The value should match your MTA's limit for a maximum attachment size.
# Default: 10M
#StreamMaxLength 20M

# Limit port range.
# Default: 1024
#StreamMinPort 30000
# Default: 2048
#StreamMaxPort 32000

# Maximum number of threads running at the same time.
# Default: 10
#MaxThreads 20

# Waiting for data from a client socket will timeout after this time (seconds).
# Value of 0 disables the timeout.
# Default: 120
#ReadTimeout 300

# Waiting for a new job will timeout after this time (seconds).
# Default: 30
#IdleTimeout 60

# Don't scan files and directories matching regex
# This directive can be used multiple times
# Default: scan all
#ExcludePath ^/proc/
#ExcludePath ^/sys/

# Maximum depth directories are scanned at.
# Default: 15
#MaxDirectoryRecursion 20

# Follow directory symlinks.
# Default: no
#FollowDirectorySymlinks yes

# Follow regular file symlinks.
# Default: no
#FollowFileSymlinks yes

# Perform a database check.
# Default: 1800 (30 min)
#SelfCheck 600

# Execute a command when virus is found. In the command string %v will
# be replaced with the virus name.
# Default: no
#VirusEvent /usr/local/bin/send_sms 123456789 "VIRUS ALERT: %v"

# Run as another user (clamd must be started by root for this option to work)
# Default: don't drop privileges
User clamav

# Initialize supplementary group access (clamd must be started by root).
# Default: no
#AllowSupplementaryGroups no

# Stop daemon when libclamav reports out of memory condition.
#ExitOnOOM yes

# Don't fork into background.
# Default: no
#Foreground yes

# Enable debug messages in libclamav.
# Default: no
#Debug yes

# Do not remove temporary files (for debug purposes).
# Default: no
#LeaveTemporaryFiles yes

# Detect Possibly Unwanted Applications.
# Default: no
#DetectPUA yes

# Exclude a specific PUA category. This directive can be used multiple times.
# See http://www.clamav.net/support/pua for the complete list of PUA
# categories.
# Default: Load all categories (if DetectPUA is activated)
#ExcludePUA NetTool
#ExcludePUA PWTool

# Only include a specific PUA category. This directive can be used multiple
# times.
# Default: Load all categories (if DetectPUA is activated)
#IncludePUA Spy
#IncludePUA Scanner
#IncludePUA RAT

# In some cases (eg. complex malware, exploits in graphic files, and others),
# ClamAV uses special algorithms to provide accurate detection. This option
# controls the algorithmic detection.
# Default: yes
#AlgorithmicDetection yes


##
## Executable files
##

# PE stands for Portable Executable - it's an executable file format used
# in all 32 and 64-bit versions of Windows operating systems. This option allows
# ClamAV to perform a deeper analysis of executable files and it's also
# required for decompression of popular executable packers such as UPX, FSG,
# and Petite.
# Default: yes
#ScanPE yes

# Executable and Linking Format is a standard format for UN*X executables.
# This option allows you to control the scanning of ELF files.
# Default: yes
#ScanELF yes

# With this option clamav will try to detect broken executables (both PE and
# ELF) and mark them as Broken.Executable.
# Default: no
#DetectBrokenExecutables yes


##
## Documents
##

# This option enables scanning of OLE2 files, such as Microsoft Office
# documents and .msi files.
# Default: yes
#ScanOLE2 yes

# This option enables scanning within PDF files.
# Default: yes
#ScanPDF yes


##
## Mail files
##

# Enable internal e-mail scanner.
# Default: yes
#ScanMail yes

# If an email contains URLs ClamAV can download and scan them.
# WARNING: This option may open your system to a DoS attack.
#          Never use it on loaded servers.
# Default: no
#MailFollowURLs no

# Scan RFC1341 messages split over many emails.
# You will need to periodically clean up $TemporaryDirectory/clamav-partial directory.
# WARNING: This option may open your system to a DoS attack.
#          Never use it on loaded servers.
# Default: no
#ScanPartialMessages yes


# With this option enabled ClamAV will try to detect phishing attempts by using
# signatures.
# Default: yes
#PhishingSignatures yes

# Scan URLs found in mails for phishing attempts using heuristics.
# Default: yes
#PhishingScanURLs yes

# Always block SSL mismatches in URLs, even if the URL isn't in the database.
# This can lead to false positives.
#
# Default: no
#PhishingAlwaysBlockSSLMismatch no

# Always block cloaked URLs, even if URL isn't in database.
# This can lead to false positives.
#
# Default: no
#PhishingAlwaysBlockCloak no

# Allow heuristic match to take precedence.
# When enabled, if a heuristic scan (such as phishingScan) detects
# a possible virus/phish it will stop scan immediately. Recommended, saves CPU
# scan-time.
# When disabled, virus/phish detected by heuristic scans will be reported only at
# the end of a scan. If an archive contains both a heuristically detected
# virus/phish, and a real malware, the real malware will be reported
#
# Keep this disabled if you intend to handle "*.Heuristics.*" viruses
# differently from "real" malware.
# If a non-heuristically-detected virus (signature-based) is found first,
# the scan is interrupted immediately, regardless of this config option.
#
# Default: no
#HeuristicScanPrecedence yes

##
## Data Loss Prevention (DLP)
##

# Enable the DLP module
# Default: No
#StructuredDataDetection yes

# This option sets the lowest number of Credit Card numbers found in a file
# to generate a detect.
# Default: 3
#StructuredMinCreditCardCount 5

# This option sets the lowest number of Social Security Numbers found
# in a file to generate a detect.
# Default: 3
#StructuredMinSSNCount 5

# With this option enabled the DLP module will search for valid
# SSNs formatted as xxx-yy-zzzz
# Default: yes
#StructuredSSNFormatNormal yes

# With this option enabled the DLP module will search for valid
# SSNs formatted as xxxyyzzzz
# Default: no
#StructuredSSNFormatStripped yes


##
## HTML
##

# Perform HTML normalisation and decryption of MS Script Encoder code.
# Default: yes
#ScanHTML yes


##
## Archives
##

# ClamAV can scan within archives and compressed files.
# Default: yes
#ScanArchive yes

# Use slower but memory efficient decompression algorithm.
# only affects the bzip2 decompressor.
# Default: no
#ArchiveLimitMemoryUsage yes

# Mark encrypted archives as viruses (Encrypted.Zip, Encrypted.RAR).
# Default: no
#ArchiveBlockEncrypted no


##
## Limits
##

# The options below protect your system against Denial of Service attacks
# using archive bombs.

# This option sets the maximum amount of data to be scanned for each input file.
# Archives and other containers are recursively extracted and scanned up to this
# value.
# Value of 0 disables the limit
# Note: disabling this limit or setting it too high may result in severe damage
# to the system.
# Default: 100M
#MaxScanSize 150M

# Files larger than this limit won't be scanned. Affects the input file itself
# as well as files contained inside it (when the input file is an archive, a
# document or some other kind of container).
# Value of 0 disables the limit.
# Note: disabling this limit or setting it too high may result in severe damage
# to the system.
# Default: 25M
#MaxFileSize 30M

# Nested archives are scanned recursively, e.g. if a Zip archive contains a RAR
# file, all files within it will also be scanned. This options specifies how
# deeply the process should be continued.
# Note: disabling this limit or setting it too high may result in severe damage
# to the system.
# Value of 0 disables the limit.
# Default: 16
#MaxRecursion 10

# Number of files to be scanned within an archive, a document, or any other
# container file.
# Value of 0 disables the limit.
# Note: disabling this limit or setting it too high may result in severe damage
# to the system.
# Default: 10000
#MaxFiles 15000


##
## Clamuko settings
## WARNING: This is experimental software. It is very likely it will hang
##          up your system!!!
##

# Enable Clamuko. Dazuko (/dev/dazuko) must be configured and running.
# Default: no
#ClamukoScanOnAccess yes

# Set access mask for Clamuko.
# Default: no
#ClamukoScanOnOpen yes
#ClamukoScanOnClose yes
#ClamukoScanOnExec yes

# Set the include paths (all files inside them will be scanned). You can have
# multiple ClamukoIncludePath directives but each directory must be added
# in a seperate line.
# Default: disabled
#ClamukoIncludePath /home
#ClamukoIncludePath /students

# Set the exclude paths. All subdirectories are also excluded.
# Default: disabled
#ClamukoExcludePath /home/bofh

# Don't scan files larger than ClamukoMaxFileSize
# Value of 0 disables the limit.
# Default: 5M
#ClamukoMaxFileSize 10M

[root@localhost root]# cat /usr/local/clamav/etc/freshclam.conf

##
## Example config file for freshclam
## Please read the freshclam.conf(5) manual before editing this file.
##


# Comment or remove the line below.
#Example

# Path to the database directory.
# WARNING: It must match clamd.conf's directive!
# Default: hardcoded (depends on installation options)
DatabaseDirectory /usr/local/clamav

# Path to the log file (make sure it has proper permissions)
# Default: disabled
UpdateLogFile /var/log/freshclam.log

# Maximum size of the log file.
# Value of 0 disables the limit.
# You may use 'M' or 'm' for megabytes (1M = 1m = 1048576 bytes)
# and 'K' or 'k' for kilobytes (1K = 1k = 1024 bytes).
# in bytes just don't use modifiers.
# Default: 1M
#LogFileMaxSize 2M

# Log time with each message.
# Default: no
#LogTime yes

# Enable verbose logging.
# Default: no
#LogVerbose yes

# Use system logger (can work together with UpdateLogFile).
# Default: no
#LogSyslog yes

# Specify the type of syslog messages - please refer to 'man syslog'
# for facility names.
# Default: LOG_LOCAL6
#LogFacility LOG_MAIL

# This option allows you to save the process identifier of the daemon
# Default: disabled
#PidFile /var/run/freshclam.pid

# By default when started freshclam drops privileges and switches to the
# "clamav" user. This directive allows you to change the database owner.
# Default: clamav (may depend on installation options)
#DatabaseOwner clamav

# Initialize supplementary group access (freshclam must be started by root).
# Default: no
#AllowSupplementaryGroups yes

# Use DNS to verify virus database version. Freshclam uses DNS TXT records
# to verify database and software versions. With this directive you can change
# the database verification domain.
# WARNING: Do not touch it unless you're configuring freshclam to use your
# own database verification domain.
# Default: current.cvd.clamav.net
#DNSDatabaseInfo current.cvd.clamav.net

# Uncomment the following line and replace XY with your country
# code. See http://www.iana.org/cctld/cctld-whois.htm for the full list.
#DatabaseMirror db.XY.clamav.net

# database.clamav.net is a round-robin record which points to our most
# reliable mirrors. It's used as a fall back in case db.XY.clamav.net is
# not working. DO NOT TOUCH the following line unless you know what you
# are doing.
DatabaseMirror database.clamav.net

# How many attempts to make before giving up.
# Default: 3 (per mirror)
#MaxAttempts 5

# With this option you can control scripted updates. It's highly recommended
# to keep it enabled.
# Default: yes
#ScriptedUpdates yes

# By default freshclam will keep the local databases (.cld) uncompressed to
# make their handling faster. With this option you can enable the compression;
# the change will take effect with the next database update.
# Default: no
#CompressLocalDatabase no

# Number of database checks per day.
# Default: 12 (every two hours)
#Checks 24

# Proxy settings
# Default: disabled
#HTTPProxyServer myproxy.com
#HTTPProxyPort 1234
#HTTPProxyUsername myusername
#HTTPProxyPassword mypass

# If your servers are behind a firewall/proxy which applies User-Agent
# filtering you can use this option to force the use of a different
# User-Agent header.
# Default: clamav/version_number
#HTTPUserAgent SomeUserAgentIdString

# Use aaa.bbb.ccc.ddd as client address for downloading databases. Useful for
# multi-homed systems.
# Default: Use OS'es default outgoing IP address.
#LocalIPAddress aaa.bbb.ccc.ddd

# Send the RELOAD command to clamd.
# Default: no
#NotifyClamd /path/to/clamd.conf

# Run command after successful database update.
# Default: disabled
#OnUpdateExecute command

# Run command when database update process fails.
# Default: disabled
#OnErrorExecute command

# Run command when freshclam reports outdated version.
# In the command string %v will be replaced by the new version number.
# Default: disabled
#OnOutdatedExecute command

# Don't fork into background.
# Default: no
#Foreground yes

# Enable debug messages in libclamav.
# Default: no
#Debug yes

# Timeout in seconds when connecting to database server.
# Default: 30
#ConnectTimeout 60

# Timeout in seconds when reading from database server.
# Default: 30
#ReceiveTimeout 60

# When enabled freshclam will submit statistics to the ClamAV Project about
# the latest virus detections in your environment. The ClamAV maintainers
# will then use this data to determine what types of malware are the most
# detected in the field and in what geographic area they are.
# This feature requires LogTime and LogFile to be enabled in clamd.conf.
# Default: no
#SubmitDetectionStats /path/to/clamd.conf

# Country of origin of malware/detection statistics (for statistical
# purposes only). The statistics collector at ClamAV.net will look up
# your IP address to determine the geographical origin of the malware
# reported by your installation. If this installation is mainly used to
# scan data which comes from a different location, please enable this
# option and enter a two-letter code (see http://www.iana.org/domains/root/db/)
# of the country of origin.
# Default: disabled
#DetectionStatsCountry country-code

3. clamav DATABASE 패턴 UP-TO-DATE
    [root@localhost root]# /usr/local/clamav/bin/freshclam
    해당 DATABASE 패턴은 /usr/local/clamav 디렉토리에 mirrors.dat, daily.cld, main.cvd 3개가 생성된다.

4. clamav 구동
    [root@localhost root]# /usr/local/clamav/sbin/clamd &
    와 같이 UP-TO-DATE 된 DATABASE 를 clamav 가 구동하였다.

5. clamav DATABASE 자동 업데이트를 위해서 CRONTAB 에 아래와 같이 등록한다.ㅣ
    [root@localhost root]# echo "30 * * * * root /usr/local/clamav/bin/freshclam" >> /etc/crontab && /etc/init.d/crond restart
6. clamav-milter 설정 및 구동
    sendmail MTA 에 활성화를 위해서는 /etc/mail/sendmail.mc 파일을 갱신해야한다.
    아래와 같이 /etc/mail/sendmail.mc 파일의 최하단에 2 라인을 추가한다.
    [root@localhost root]# vi /etc/mail/sendmail.mc
        INPUT_MAIL_FILTER(`clamav', `S=local:/var/run/clamav/clmilter.sock, F=, T=S:4m;R:4m;C:30s;E:10m')dnl
        define(`confINPUT_MAIL_FILTERS', `clamav')

    [root@localhost root]# m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf

    이제 clamav-milter 를 구동하고, sendmail 을 restart 한다.
    [root@localhost root]# /usr/local/clamav/sbin/clamav-milter --max-children=100 -lo /var/run/clamav/clmilter.sock &
    [root@localhost root]# /etc/init.d/sendmail restart

7. 모든 구성이 완료되었으며, clamav-milter 가 감지한 메일은 메일 제목에 Virus Intercepted 라는 제목으로 해당 메일이 전송된다.

8. 만일 File Server 나 배포되는 /home 디렉토리에서 바이러스를 검사하고 싶다면 아래와 같이 하면 된다.
    [root@localhost root]# /usr/local/clamav/bin/clamscan -r /home
    클린 파일들은 OK 라고 출력되며, 바이러스에 감염된 파일은 해당 바이러스명이 출력된다.

9. 부팅시에 자동으로 구동되도록 아래와 같은 라인을 /etc/rc.d/rc.local 파일에 추가한다.
    /usr/local/clamav/sbin/clamav-milter --max-children=100 -lo /var/run/clamav/clmilter.sock &
    /usr/local/clamav/sbin/clamd &

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