Subject Re: Firebird Security Authentication Configuration Questions
Brief answer is "no" for both questions. But this does not mean that such task is impossible, just that nobody used to pay attention to it cause in theory I see no reasons why this can not be done.

Trusted authentication has 2 steps. First, client should pass to the server context of logged in user. Next server determines login name for that context. If we find in linux (not sure where should they be - in sambe? in pam?) calls performing same tasks compiling plugin for linux will not be a problem.

List of required API functions FYI is :
AcquireCredentialsHandle, DeleteSecurityContext, FreeCredentialsHandle, QueryContextAttributes,
FreeContextBuffer, InitializeSecurityContext, AcceptSecurityContext,
GetTokenInformation, AllocateAndInitializeSid, EqualSid, FreeSid

May be I missed one or two but suppose that's not critical for now.