ssmax You can use NCM to download a great many things from a Linux server, however, you must configure a new device template, as well as config type, first.
Here are a couple of links which may help you.
Other than that, you will obviously need credentials for connecting to your Linux servers. Otherwise, that's about it. Once you get the first couple of things setup, it should just work like any other NCM node.
Let us know how it goes, and if you need any further assistance.
NCM is designed to be used with network devices (and not for backing up Windows/Linux files) and thus supports the following file extensions:
NCM Archive: .Config
SolarWinds Cisco Config Downloader: .CiscoConfig
Text File: .txt
Configuration File: .cfg
Any file in ASCII text
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