Security Considerations for the InnoDB memcached Plugin To get values greater than  B  but less than  M , enter  get @>B@<M : A maximum of two comparison operators can be parsed, one being either a ’less than’ ( @< ) or ’less than or equal to’ ( @<= ) operator, and the other being either a ’greater than’ ( @> ) or ’greater than or equal to’ ( @>= ) operator. Any additional operators are assumed to be part of the key. For example, if you issue a  get command with three operators, the third operator ( @>C ) is treated as part of the key, and the  get  command searches for values smaller than  M  and greater than  B@>C . Consult this section before deploying the  daemon_memcached  plugin on a production server, or even on a test server if the MySQL instance contains sensitive data. Because  memcached  does not use an authentication mechanism by default, and the optional SASL authentication is not as strong as traditional DBMS security measures, only keep non-sensitive data in the MySQL instance that uses the  daemon_memcached  plugin, and wall off any servers that use this configuration from potential intruders. Do not allow  memcached  access to these servers from the Internet; only allow access from within a firewalled intranet, ideally from a subnet whose membership you can restrict. SASL support provides the capability to protect your MySQL database from unauthenticated access through  memcached  clients. This section explains how to enable SASL with the  daemon_memcached plugin. The steps are almost identical to those performed to enabled SASL for a traditional  memcached server. SASL stands for “Simple Authentication and Security Layer” , a standard for adding authentication support to connection-based protocols.  memcached  added SASL support in version 1.4.3. SASL authentication is only supported with the binary protocol. memcached  clients are only able to access  InnoDB  tables that are registered in the innodb_memcache.containers  table. Even though a DBA can place access restrictions on such tables, access through  memcached  applications cannot be controlled. For this reason, SASL support is provided to control access to  InnoDB  tables associated with the  daemon_memcached  plugin. The following section shows how to build, enable, and test an SASL-enabled  daemon_memcached  plugin. 3365 Password-Protecting memcached Using SASL Caution 15.20.5 Security Considerations for the InnoDB memcached Plugin get @<M@>B@>C VALUE C 0 21 CHENNAI|TAMIL NADU|IN VALUE D 0 14 DELHI|DELHI|IN VALUE H 0 22 HYDERABAD|TELANGANA|IN get @>B@<M VALUE C 0 21 CHENNAI|TAMIL NADU|IN VALUE D 0 14 DELHI|DELHI|IN VALUE H 0 22 HYDERABAD|TELANGANA|IN END MUMBAI|MAHARASHTRA|IN