centos

Minimizing downtime associated with Web/DNS/Mail IP address migrations

Migrating servers to new datacenters or IP addresses is never entirely problem free, usually due to many DNS servers on the internet not obeying TTL’s or caching old records for way too long. These old cached DNS records (usually at different ISP’s, major mailservers like google, hotmail, yahoo, etc.) cause problems where they’ll route mail Continue reading Minimizing downtime associated with Web/DNS/Mail IP address migrations

VMWare 2.0.x and CentOS 5.4 glibc crashes and instabilities – a workaround solution

If you’re running VMWare Server 2.0.x on CentOS 5.4, you’ll have noticed that you (most likely) suffer random reboots and other instabilities on the guest operating systems – this is due to a glibc error in vmware’s libraries, and has yet to be fixed by vmware (thanks a lot).  The real issue is CentOS/Redhat has Continue reading VMWare 2.0.x and CentOS 5.4 glibc crashes and instabilities – a workaround solution

Yum update check script – runs via crontab and emails when new updates are available

Here’s a quick script that will check yum updates and email you when there are new updates available. Split into two sections, one script is for all package updates, and the other script is for letting us know if we need to reboot when a new kernel package has been installed. Script to check for Continue reading Yum update check script – runs via crontab and emails when new updates are available

Plesk 9.x overuse policy (and how to avoid domains being suspended)

Parallels, in their infinite wisdom, introduced new “overuse” policies into their Plesk control panel as of version 9.0.  A great idea when just starting out, but a nightmare when upgrading from a previous version, since it changes the default behavior when clients and domain owners reach their pre-assigned limits.  Now, instead of just warning that Continue reading Plesk 9.x overuse policy (and how to avoid domains being suspended)

Upgrading MailScanner

Easy Upgrading of MailScanner – RPM version (For Redhat/Centos – updated from the MailScanner documentation) 1) Make a backup copy of your current MailScanner (Linux): cp -a /etc/MailScanner /etc/MailScanner.$(date +%Y%m%d) cp -a /usr/lib/MailScanner /usr/lib/MailScanner.$(date +%Y%m%d) cp -a /usr/sbin/MailScanner /usr/sbin/MailScanner.$(date +%Y%m%d) 2) Download the latest version and extract http://mailscanner.info/downloads.html Check the changelog for upgrade notes and Continue reading Upgrading MailScanner

Sendmail premissions error stopping mail from sending on CentOS 5.1

Really stupid issue with permissions on CentOS 5.1 and real easy fix, since there were improper permissions on the mqueue and clientmqueue directories. The Error message: Tried to send mail via command line using ‘mail’ command, and it returned this error: can not chdir(/var/spool/clientmqueue/): Permission denied Program mode requires special privileges, e.g., root or TrustedUser. Continue reading Sendmail premissions error stopping mail from sending on CentOS 5.1