Problem Definition

Currently, there's no option to disable the CAPTCHA for customers to log in, only signup.
On closed network systems CAPTCHA will not resolve.

Suggested Solution

Implement an option that would allow the project admins to choose whether they want their service desk to have CAPTCHA enabled to prevent possible spam or disabled to facilitate the customer's logins.

Workaround

The number of requests for Jira to show a CAPTCHA is set in System > General configuration and blank means the CAPTCHA is disabled.

This does not work in Oracle databases, in that case, you may set this value to a very high number of attempts.