CircleCI builds are currently run mainly from AWS East and West. Google Cloud Platform and additional services may be used in the future. For this reason we can't give a list of IP addresses that our cloud system will use.
Some options you might like to try instead of whitelisting:
- set a password for connecting to the machine you need
- use a jumphost that you connect to from CircleCI and is whitelisted for the external server
- consider our on premise server solution: https://circleci.com/enterprise/ where you can specify your own IP ranges.