Hmm, looks like these samples don't work correctly with Linux :-(
I recommend using the enhanced samples mentioned earlier. In this case you may try to fix it (but perhaps other issue could occur later). Look for ExtractCertificateThumbprintFromFaultMessage in ConverterCommection.cs. The regex for the thumprint has a repetition of 19. This is OK for Windows SSL thumbprints but Linux SSH fingerprints are shorter - it should be 15 for them. OTOH this code validates also VC/ESX certificates, so you cannot just replace it with 15.
Either enter the fingerprint in the properties file as a workaround or start using the enhanced samples (or have a look at them and check this f-n)
HTH
Plamen