Technical insights and best practices for Server Administration
How to build reports from raw Apache or Nginx access logs with AWStats on CentOS 6: log format, config, cron, protected access, and limits.
A reference setup for Postfix on CentOS 6 (2012): fix mail rejected or sent to spam with matching DNS, restricted SMTP, TLS submission with SASL, SPF and DKIM.
How to tell when an OpenVZ container is being refused resources: read user_beancounters, interpret failcnt, and shrink MySQL and Apache to fit the limits.
A 2010-era baseline for CentOS 5 and Ubuntu 10.04: key-only SSH, a default-drop iptables policy, sysctl network settings and fewer listening services.
Why plain FTP exposes credentials, and how to lock users into a directory with OpenSSH ChrootDirectory and internal-sftp on CentOS 5.
Why Apache prefork wastes RAM on static files and slow clients, and how a lighttpd front end plus tuned MaxClients and keep-alive fixes it on CentOS 5.
A 2009 reference for VPS users on container-based hosting: why "Cannot allocate memory" appears while free shows RAM, and how to read and fix it.
Why services in an OpenVZ container fail with allocation errors while free memory looks fine, and how to find and raise the exhausted User Beancounter limit.