I guess this here?

https://www.ccc.de/en/updates/2005/unvereinbarkeitserklaerun...

> By this we mean not only numerous “free comradeships” but also groups such as the “Deutsche Liga für Volk und Heimat”, DVU, FPÖ, the “Hilfsgemeinschaft Nationaler Gefangener”, Lijst Pim Fortuyn (Partij LPF), NPD, ProKöln and “Die Republikaner”.

These are all small splinter parties, aside from the right-populist FPÖ who was recently in the government coalition in Austria and has 60000 members.

This is an _open_ list from 2005. They consider other, similar parties to be part of the list too. I.e. the AfD was founded only years later so it's not part of the list but still considered unwelcome by most.

for reference: https://www.ccc.de/en/updates/2005/unvereinbarkeitserklaerun...

For those who need to search, that seems to roughly translate to "declaration of non-compatibility". CCC had declared that members of far-right groups are not welcome.

I don't think the KKK are a very good analogy for this; a better example might be McCarthyists/the House Committee on Un-American Activities, since they attack people based on political affiliation, which is at least nominally chosen, rather than inborn characteristics like skin color. Also the KKK made much more use of direct physical violence, rather than social and legal violence.