Change Swappiness

I installed CentOS on VirtualBox on my work laptop which has very poor specs. I gave it 512 MB RAM and a single core. Within about 20 minutes the VM started swapping and the whole laptop became extremely slow. I had been researching the problem and came across "swappiness".

I have changed this setting to zero (0) on this VM. I will test and report back.

What is swappiness and how to change it?

Fedora + Postfix + Dovecot + TLS/SSL + SASL

I was trying to set up Postfix with Dovecot, TLS/SSL on a new server and came across some issues so I documented them here and the install process again.

Tutorials Used

• Fedora Mail Server
• Postfix on CentOS

Install the Following

• Postfix
• Dovecot
• OpenSSL
• MailX
• SASLAuthD

Configure Postfix according to my previous article on the blog

In /etc/dovecot/conf.d/10-auth.conf add the following:

passdb {

driver = pam

}

Forward these Ports to the Mailserver if Behind Gateway

smtp: 25, 2525, 3535

smtp submission: 587

smtp over ssl: 465

pop3: 110, 995

imap: 143, 220, 993, 585

Activate and start all the above daemons using chkconfig and service saslauthd on etc.

Issue #1

Ran into a problem where Postfix would not relay mail for its own domain.

Had to add $mydomain to "mydestination" directive.

Issue #2

/var/log/maillog said mail coming from outside is going to root@platinumfactor.com even though the user exists on the system.

saslauthd service was not running. Also removed these from main.cf

smtpd_sasl_type = dovecot

smtpd_sasl_path = private/auth

Issue #3

Outgoing mail was not being delivered.

I had enabled TLS and provided a certificate to Postfix.

The client needed to be told to use SSL/TLS.

Issue #4

Set disable_plaintext_auth = yes

Incoming mail not being delivered.

Set client to use Secure POP (port 995)

Open Source Alternatives

At the time of this writing some OS solutions exist for several enterprise functions. Here are some of them that could help manage Linux and end user systems.


OS Applications for Central Authentication:

• Apache Directory Project
• 389 Directory Server
• OpenLDAP with Kerberos

OS Applications for Systems Management:

• Puppet - Complete configuration and update management.
• Spackwalk - Complete configuration and update management from Red Hat.
• Cobbler - Image provisioning with PXE boot.
• ClusterSSH - Generally, not for a very large environment
• Func - This is a Fedora Project. Very cool tool.

Here is a great PDF document that explains how to use Cobbler, Puppet, and Func combined for maximum automation


FOSS Products for Remote [Central] Monitoring

• Nagios
• Zenoss
• OpenNMS

Use Zimbra for mail and calendering; Alfresco for collaboration.