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July 27, 2022
Updated August 16, 2022

Centos 7 and memcached - how to use

CentOS Linux

Why should you use memcached in Centos 7

Each operation system uses much temporary data upon services work. By default, it stores into the special folder on the disk. This method has one negative side - disk read/write operations is so slow even on modern SSD. The best way to avoid this is store temp-files to the RAM, e.g. via memcached.

Requirements

To install caching service and secure it you need to have:

  • Server with Linux operation system, e.g. Centos 7
  • root access or account with sudo membership
  • Optional - iptables or another firewall

Install main package and support tools

Setup is one-line command procedure:

  • Authorize on the server and install necessary packages
sudo -s
yum install memcached -y

pic.1

Service configuration

Installed service read its settings from the /etc/sysconfig/memcached file. The most useful flags is:

CACHESIZE # RAM amount, reserved for for caching
PORT # TCP-port which is service-listened
-l # listened IP-address, usually 127.0.0.1 for local connections or "dedicated" address for "external" incoming connections
MAXCONN # allowed simultaneous connections quantity
-S # this option is enables authentication (see further)

pic.2

To accept incoming connections please allow them in the firewall settings:

firewall-cmd --permanent --zone=public --add-port=<PORT>/tcp

pic. 3

The safety improoving

If your server is accessible from the worldwide, a few security-steps would be nice. Make follow steps to implement simple authentication into memcached:

  • Installation command
yum install cyrus-sasl-devel cyrus-sasl-plain -y

pic. 4

  • Create the configuration files:
mkdir -p /etc/sasl; nano /etc/sasl/memcached.conf

pic. 5

  • Then you should fix file permissions and add the "separated" user account for authorization:
saslpasswd2 -a memcached -c -f /etc/sasl/sasldb <MEMCACHED_USERNAME>
chown memcached:memcached /etc/sasl/sasldb

pic. 6

  • Next step is enabling authentication in memcache configuration. Just add -S flag

pic. 7

  • To apply the settings service should be restarted:
service memcached restart

Checking the result

You can simply check is caching service run or not. Just run:

netstat -tulpn | grep cach

You should see something like this

pic. 8

Summary

This instruction said you why you should use caching, how to install and use this.

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