LinuxCBT qmail Edition, a component of LinuxCBT Mail Edition, focuses on the second most popular Mail Transfer Agent (MTA), qmail, and ancillary components.
qmail is used by some of the biggest names on the Net such as Yahoo!, for moving large volumes of mail, rapidly. Its design is entirely modular with an emphasis on security and rapid delivery. Additionally, many tasks in qmail can be accomplished via standard Linux/UNIX shell constructs: Pipes & redirection. Consequently, advanced Linux/UNIX Admins are comfortable with its DIY approach.
Let LinuxCBT Mail Edition help to solidify your understanding of the qmail MTA and ancillary components.
Recommended Prerequisites:
- Familiarity with electronic mail concepts (MUA/MTA/etc.)
- Access to a GNU/Linux-based PC to install the MTAs and ancillary components used
LinuxCBT qmail Edition - Disc 1
- qmail - Installation
- Identify current Mail Transfer Agent (MTA) environment on Red Hat Enterprise box
- Discuss system initialization environment
- Disable current MTA in applicable run-levels
- Identify qmail pre-requisites
- Setup qmail source-tree hierarchy for build process
- Discuss qmail's modular, component architecture - relevant binaries
- Navigate to a close qmail mirror
- Download qmail components
- Extract primary qmail packaged and dicuss contents
- Patch original qmail sources
- Install ucspi-tcp - INETD/XINETD substitute
- Install dameontools - daemon management for qmail daemons
- Create requisite users and groups
- Compile and install qmail
- Define default qmail environment
- Explore and discuss the important qmail directories, symlinks and binaries
- Illustrate internal qmail communications required for local and remote deliveries
- Identify initial qmail startup process
- Define genersal startup scripts for qmail
- Define supervise scripts for qmail delivery
- Define supervise scripts for qmail logging
- Backup default local queue-injection process (Sendmail)
- Create Sendmail symlink to qmail-compatible binary for local queue-injection
- Start qmail & confirm processes and network bindings
- qmail - Local Mail
- Define required system aliases using qmail files
- Configure qmail rules to permit local relaying
- Identify default mbox mail storage format
- Use MUA mutt to deliver mail via qmail
- Examine delivery via qmail logs
- Identify mbox destination
- Discuss local queue-injection logic - qmail-inject/Sendmail
- Explain permissions used by qmail when delivering local mail
- Update local user's environment variables and confirm message delivery
- Identify variables used for local queue-injection
- Explore and discuss the mbox mail storage format
- Update global environment configuration to reflect new mbox storage location
- Examine running qmail statistics
- Inject messages into the queue of a downed MTA
- Examine results
- Explore a message's path throught the local queue
- Resume message delivery
- qmail - Mail Storage Formats
- Switch qmail global configuration from mbox to Maildir storage format
- Use maildirmake to create Maildir-compliant directory structure for users
- Explore standard Maildir directory tree
- Restart qmail and attempt delivery to Maildir mailbox
- Confirm deliver of message to Maildir recipient
- Discuss Maildir file nomenclature
- Update environment variables to reflect Maildir mail storage format
- Explore headers of delivered messages and discuss key components
- qmail - Aliases
- Explain the benefits of aliases
- Explore traditional Sendmail-style aliases in /etc/aliases
- Compare and contrast Sendmail-style aliases to qmail-style (.qmail) aliases
- Discuss key qmail alias user
- Explore system-wide qmail aliases
- Test delivery to system-wide qmail aliases
- Define an abuse qmail-style alias and confirm delivery
- Deine one-to-many qmail-style abuse alias and confirm delivery
- Attempt delivery to non-existing local user or alias using Sendmail and confirm results
- Define a catch-all system-wide alias to handle non-existing local users or accounts
- Test catch-all system-wide alias by injecting messages bound to non-existing mailboxes
- Discuss sub-addresses/address extensions using qmail aliases
- Define sub-address for non-privileged user and confirm delivery using MUA mutt
- Forward defined non-privileged sub-address to other local user and examine results
- Redirect the abuse alias to a Mailbox-style repository for evidence-collection
- Confirm appended alias-redirection of messages destined to catch-all accounts
- qmail - Remote Mail
- Identify key qmail daemons and binaries responsible for remote delivery
- Explain remote delivery logic using DNS
- Connect (SSH) to remote Linux system to be used for initial remote delivery & explore
- Attempt remote delivery using qmail and FQDN of remote box and examine the qmail queue
- Alter remote Postfix environment to find Maildir mailbox and confirm delivery using mutt
- Update remote Postfix configuration to handle messages destined to second-level domain
- Alter remote Postfix transport (smtproutes) file to disable static delivery
- Confirm DNS second-level Mail Exchanger (MX) configuration for linuxcbt.internal domain
- Attempt MX-based delivery and confirm delivery on remote host
- Discuss employed qmail logic
- Switch primary Mail Exchanger (MX) from Postfix box to qmail box - adjusting distances
- Confirm MX distances using Domain Information Groper (dig)
- Attempt delivery to second-level domain from the qmail box & confirm delivery
- Explore qmail log files for message-delivery information
- Debug qmail-smtpd delivery issues and adjust to ensure delivery
- Discuss a Backup MX configuration for a given domain
- Update DNS configuration to reflect the ideal MX distances
- Confirm DNS configuration from a tertiary Linux server
- Purposely fail the primary Postfix server for the linuxcbt.external domain
- Configure qmail to be a Backup MX server for a business partner's domain
- Attempt delivery to the linuxcbt.external domain from the tertiary Linux server
- Examine queued messages for the linuxcbt.external backup domain on the qmail box
- Re-enable the primary domain's Postfix box
- Flush the qmail queue and examine delivery to the primary MX host
- qmail - Relay Control
- Discuss Smart Host applications
- Explore pre-Smart Host SMTP delivery of messages to Internet-based host
- Configure qmail to use a remote Postfix SMTP Smart Host system
- Disable Smart Host configuration
- Discuss qmail's default relay policy
- Identify key qmail configuration files related to relaying
- Attempt to relay from a remote Windows 2003 Host through the open qmail MTA
- Confirm delivery of message via qmail in open-relay mode to local and remote recipients
- Secure open relay and confirm inability to relay messages to untrusted domains
- Configure selective relaying based on individual host and subnet
- Discuss the benefits of SMTP Auth
- Explain qmail's SMTP Auth implementation
- Identify SMTP Auth pre-requisites
- Download, compile and install CheckPassword authentication application
- Debug compilation-related errors
- Download SMTP Auth patch
- Patch qmail sources and recompile to produce modified qmail-smtpd binary
- Install new qmail-smtpd binary and prepare run scripts for usage
- Attempt to relay with tightened relay permissions and confirm failure
- Confirm SMTP Auth from Windows 2003 Host using Outlook Express
- Relay outbound messages using SMTP Auth from Outlook Express client
- qmail - Network-based Mail Retrieval
- Discuss Mail retrieval authentication framework using Courier
- Identify pre-requisites
- Download, compile and install Courier Authentication Daemon
- Identify Courier Authentication key directories, binaries and configuration file
- Download and install Courier IMAP Daemon
- Explore Courier IMAP binary directory tree
- Discuss Courier framework
- Configure Courier for POP3 mail retrieval
- Confirm retrieval using Windows 2003 - Outlook Express client
- Identify POP3 Secure configuration files
- Generate self-signed certificate for use with POP3 Secure communications
- Confirm retrieval of messages using Outlook Expres and POP3 Secure
- Establish run-level symbolic links for POP3 & POP3S services
- Configure Courier for IMAP mail retrieval
- Confirm retrieval using Windows 2003 - Outlook Express client
- Generate self-signed certificate for use with IMAP Secure communications
- Establish run-level symbolic links for IMAP & IMAPS services
- qmail - Web-based Mail Retrieval
- Discuss Web-based SquirrelMail pre-requisites
- Enable Apache web server
- Download and Install SquirrelMail into web-accessible location
- Secure data and attachments directories
- Configure SquirrelMail for initial use with Courier IMAP
- Address PHP session-related issues
- Explore SquirrelMail from the browser as various Linux users
- Confirm deliver using multiple clients - (mutt/Outlook Express/SquirrelMail/Local Injection)
- qmail - Virtual Domains
- Discuss qmail virtual domains support via system-wide aliases
- Configure basic/global virtual domains using .qmail files
- Confirm delivery to users @ virtual domains
- Configure individual virtual domains
- Confirm delivery to individuals @ virtual domains
- Ensure non-global delivery to virtual domains
- Define non-privileged user-managed virtual domains
- Confirm deliver to user-managed virtual domains
- qmail - Malware Framework - OpenProtect, Bad Senders, TLS
- Discus the OpenProtect Malware Framework
- Identify pre-requisites
- Download OpenProtect
- Install Open Protect
- Explore OpenProtect Configuration (MailScanner/ClamAV/SpamAssAssin)
- Configure outbound signatures
- Configure qmail to reject users based header information
- Confirm rejection from Windows 2003 Host - Outlook Express
- Discuss Transport Layer Security framework and requirements
- Implement Transport Layer Security (TLS)
- Configure Outlook Express client to use TLS & test outbound relaying
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