General Information

Memcached is a “distributed memory object caching system”. Useful for speeding up web applications by caching database lookups.

Official Site: http://www.memcached.org/

Checklist

• Distro(s): Enterprise Linux
• Repo: EPEL (if using EL 5/6)

1. Memcached is in EL 7's base repo. If you are using EL 5/6, you will need to add the EPEL repo.
   1. Add the EPEL repo
2. Install memcached

   yum install memcached

3. Start and enable the service
   1. EL 6

      service memcached start
      chkconfig memcached on

   2. EL 7

      systemctl start memcached
      systemctl enable memcached

• Edit the config file

  vim /etc/sysconfig/memcached
   
  # Daemon
  USER="memcached"
   
  # Reserved Cache in MBs
  CACHESIZE="2048"
   
  # Memcached Options - Listen on localhost only
  OPTIONS="-l 127.0.0.1"
   
  # Memcached Options - Clear out to listen on any interface
  #OPTIONS=""
   
  # Networking
  PORT="11211"
  MAXCONN="1024"

  • OPTIONS ⇒ Set other daemon options (see man memcaced)
• If you made any config file changes, restart the service.

Memcached does not have any application authentication, so you should configure the memcached server with firewall rules to only allow certain sources to utilize it on tcp and udp port 11211 (the default port).

• Either listen locally, or setup firewall rules to protect the cache.
  • See pages on Firewall-cmd or IPTables for syntax details.