Mail filtering with spam-assassin
by Uday R. Sawant, William Leemans, Jonathan Hobson, Oliver Pelz
Linux: Powerful Server Administration
- Linux: Powerful Server Administration
- Table of Contents
- Linux: Powerful Server Administration
- Linux: Powerful Server Administration
- Credits
- Preface
- 1. Module 1
- 1. Managing Users and Groups
- 2. Networking
- Introduction
- Connecting to a network with a static IP
- Installing the DHCP server
- Installing the DNS server
- Hiding behind the proxy with squid
- Being on time with NTP
- Discussing load balancing with HAProxy
- Tuning the TCP stack
- Troubleshooting network connectivity
- Securing remote access with OpenVPN
- Securing a network with uncomplicated firewall
- Securing against brute force attacks
- Discussing Ubuntu security best practices
- 3. Working with Web Servers
- Introduction
- Installing and configuring the Apache web server
- Serving dynamic contents with PHP
- Hosting multiple websites with a virtual domain
- Securing web traffic with HTTPS
- Installing Nginx with PHP_FPM
- Setting Nginx as a reverse proxy
- Load balancing with Nginx
- Setting HTTPs on Nginx
- Benchmarking and performance tuning of Apache
- Securing the web server
- Troubleshooting the web server
- 4. Working with Mail Servers
- 5. Handling Databases
- Introduction
- Installing relational databases with MySQL
- Storing and retrieving data with MySQL
- Importing and exporting bulk data
- Adding users and assigning access rights
- Installing web access for MySQL
- Setting backups
- Optimizing MySQL performance – queries
- Optimizing MySQL performance – configuration
- Creating MySQL replicas for scaling and high availability
- Troubleshooting MySQL
- Installing MongoDB
- Storing and retrieving data with MongoDB
- 6. Network Storage
- 7. Cloud Computing
- 8. Working with Containers
- Introduction
- Installing LXD, the Linux container daemon
- Deploying your first container with LXD
- Managing LXD containers
- Managing LXD containers – advanced options
- Setting resource limits on LXD containers
- Networking with LXD
- Installing Docker
- Starting and managing Docker containers
- Creating images with a Dockerfile
- Understanding Docker volumes
- Deploying WordPress using a Docker network
- Monitoring Docker containers
- Securing Docker containers
- 9. Streaming with Ampache
- 10. Communication Server with XMPP
- 11. Git Hosting
- Introduction
- Installing Git
- Creating a local repository with Git CLI
- Storing file revisions with Git commit
- Synchronizing the repository with a remote server
- Receiving updates with Git pull
- Creating repository clones
- Installing GitLab, your own Git hosting
- Adding users to the GitLab server
- Creating a repository with GitLab
- Automating common tasks with Git hooks
- 12. Collaboration Tools
- 13. Performance Monitoring
- 14. Centralized Authentication Service
- 2. Module 2
- 1. Installing CentOS
- Introduction
- Downloading CentOS and confirming the checksum on Windows or OS X
- Creating USB installation media on Windows or OS X
- Performing an installation of CentOS using the graphical installer
- Running a netinstall over HTTP
- Installing CentOS 7 using a kickstart file
- Getting started and customising the boot loader
- Troubleshooting the system in rescue mode
- Updating the installation and enhancing the minimal install with additional administration and development tools
- 2. Configuring the System
- Introduction
- Navigating text files with less
- Introduction to Vim
- Speaking the right language
- Synchronizing the system clock with NTP and the chrony suite
- Setting your hostname and resolving the network
- Building a static network connection
- Becoming a superuser
- Customizing your system banners and messages
- Priming the kernel
- 3. Managing the System
- Introduction
- Knowing and managing your background services
- Troubleshooting background services
- Tracking system resources with journald
- Configuring journald to make it persistent
- Managing users and their groups
- Scheduling tasks with cron
- Synchronizing files and doing more with rsync
- Maintaining backups and taking snapshots
- Monitoring important server infrastructure
- Taking control with GIT and Subversion
- 4. Managing Packages with YUM
- 5. Administering the Filesystem
- 6. Providing Security
- 7. Building a Network
- 8. Working with FTP
- 9. Working with Domains
- 10. Working with Databases
- 11. Providing Mail Services
- 12. Providing Web Services
- 13. Operating System-Level Virtualization
- 14. Working with SELinux
- 15. Monitoring IT Infrastructure
- 1. Installing CentOS
- 3. Module 3
- 1. Working with KVM Guests
- 2. Deploying RHEL "En Masse"
- 3. Configuring Your Network
- 4. Configuring Your New System
- 5. Using SELinux
- 6. Orchestrating with Ansible
- 7. Puppet Configuration Management
- 8. Yum and Repositories
- 9. Securing RHEL 7
- 10. Monitoring and Performance Tuning
- Bibliography
- Index
In this recipe, we will learn how to install and set up a well-known e-mail filtering program, spam-assassin.
You will need access to a root account or an account with sudo privileges.
You need to have Postfix installed and working.
Follow these steps to filter mail with spam-assassin:
- Install spam-assassin with the following command:
$ sudo apt-get update $ sudo apt-get install spamassassin spamc
- Create a user account and group for spam-assassin:
$ sudo groupadd spamd $ sudo useradd -g spamd -s /usr/bin/nologin -d /var/log/spamassassin -m spamd
- Change the default settings for the spam daemon. Open
/etc/default/spamassassinand update the following lines:ENABLED=1 SAHOME="/var/log/spamassassin/" OPTIONS="--create-prefs --max-children 5 --username spamd --helper-home-dir ${SAHOME} -s ${SAHOME}spamd.log" PIDFILE="${SAHOME}spamd.pid" CRON=1 - Optionally, configure spam rules by changing values in
/etc/spamassassin/local.cf:trusted_networks 10.0.2. # set your trusted network required_score 3.0 # 3 + will be marked as spam
- Next, we need to change the Postfix settings to pass e-mails through spam-assassin. Open
/etc/postfix/master.cfand find the following line:smtp inet n - - - - smtpd
- Add the content filtering option:
-o content_filter=spamassassin
- Define the content filter block by adding the following lines to the end of the file:
spamassassin unix - n n - - pipe user=spamd argv=/usr/bin/spamc -f -e /usr/sbin/sendmail -oi -f ${sender} ${recipient}
- Finally, restart spam-assassin and Postfix:
$ sudo service spamassassin start $ sudo service postfix reload
- You can check spam-assassin and mail logs to verify that spam-assassin is working properly:
$ less /var/log/spamassassin/spamd.log $ less /var/log/mail.log
Spam filtering works with the help of a piping mechanism provided by Postfix. We have created a new Unix pipe which will be used to filter e-mails. Postfix will pass all e-mails through this pipe, which will be then scanned through spam-assassin to determine the spam score. If given e-mail scores below the configured threshold, then it passes the filter without any modification; otherwise, spam-assassin adds a spam header to the e-mail.
Spam-assassin works with a Bayesian classifier to classify e-mails as spam or not spam. Basically, it checks the content of the e-mail and determines the score based on content.
You can train spam-assassin's Bayesian classifier to get more accurate spam detections.
The following command will train spam-assassin with spam contents (--spam):
$ sudo sa-learn --spam -u spamd --dir ~/Maildir/.Junk/* -D
To train with non-spam content, use the following command (--ham):
$ sudo sa-learn --ham -u spamd --dir ~/Maildir/.INBOX/* -D
If you are using the mbox format, replace --dir ~/Maildir/.Junk/* with the option --mbox.
- Sa-learn - train SpamAssassin's Bayesian classifier at https://spamassassin.apache.org/full/3.2.x/doc/sa-learn.html and https://wiki.apache.org/spamassassin/BayesInSpamAssassin
- Learn about Bayesian classification at https://en.wikipedia.org/wiki/Naive_Bayes_classifier
-
No Comment
..................Content has been hidden....................
You can't read the all page of ebook, please click here login for view all page.