Book Image

Linux Networking Cookbook

By : Agnello Dsouza, Gregory Boyce
5 (1)
Book Image

Linux Networking Cookbook

5 (1)
By: Agnello Dsouza, Gregory Boyce

Overview of this book

Linux can be configured as a networked workstation, a DNS server, a mail server, a firewall, a gateway router, and many other things. These are all part of administration tasks, hence network administration is one of the main tasks of Linux system administration. By knowing how to configure system network interfaces in a reliable and optimal manner, Linux administrators can deploy and configure several network services including file, web, mail, and servers while working in large enterprise environments. Starting with a simple Linux router that passes traffic between two private networks, you will see how to enable NAT on the router in order to allow Internet access from the network, and will also enable DHCP on the network to ease configuration of client systems. You will then move on to configuring your own DNS server on your local network using bind9 and tying it into your DHCP server to allow automatic configuration of local hostnames. You will then future enable your network by setting up IPv6 via tunnel providers. Moving on, we’ll configure Samba to centralize authentication for your network services; we will also configure Linux client to leverage it for authentication, and set up a RADIUS server that uses the directory server for authentication. Toward the end, you will have a network with a number of services running on it, and will implement monitoring in order to detect problems as they occur.
Table of Contents (19 chapters)
Linux Networking Cookbook
About the Author
About the Reviewer

Configuring authentication for outbound e-mail

With our current mail server setup, we can retrieve e-mail remotely and we can send mail from the local box, but we cannot send mail from remote systems. In order to enable this functionality, we need to configure Postfix to require auth for sending outbound mail from remote users. Typically, this requires setting up a SASL server of some variety like Cyrus saslauthd. In our case, we're going to use Dovecot's built in SASL server.

How to do it…

  1. Configure Dovecot to expose its SASL interface to Postfix by editing /etc/dovecot/conf.d/10-master.conf:

    service auth {
      unix_listener /var/spool/postfix/private/auth {
        group = postfix
        mode = 0660
        user = postfix
  2. Configure Postfix to authenticate via SASL by editing and adding:

    submission inet n - n - - smtpd
      -o smtpd_tls_security_level=encrypt
      -o smtpd_sasl_auth_enable=yes
      -o smtpd_sasl_type=dovecot
      -o smtpd_sasl_path=private/auth
      -o smtpd_sasl_security_options=noanonymous...