Configure four-letter-word commands in ZooKeeper

Four-letter-words commands are simple diagnostics commands that can be used over telnet for ZooKeeper. These commands can be configured with Cloudera Manager.

You can configure which four-letter-words commands you want to enable in ZooKeeper. By default the wchp and the wchc commands are disabled.

  1. In Cloudera Manager, select the ZooKeeper service.
  2. Click the Configuration tab.
  3. Search for 4lw.
  4. Find the ZooKeeper 'Four Letter Word' Command Whitelist property.
  5. Use the minus and plus icon to remove or add four-letter-word commands to the whitelist.

    By default the following commands are on the whitelist: conf, cons, crst, dirs, dump, envi, gtmk, ruok, stmk, srst, stat, wchs, mntr, and isro.

    The wchp and wchc commands are not enabled by default because of their known DOS vulnerability. For more information, see ZOOKEEPER-2693and Zookeeper 3.5.2 - Denial of Service.

    If * is set, all commands are enabled.

  6. Click Save Changes.