Add support for RFC 8308 Extension Negotiation
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- Dominant language
- C#
- Stars
- 4.4k
- Forks
- 993
- Avg merge
- 9d 21h
- Merged PRs (30d)
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Description
We should add support for RFC8308 extension negotation, and primarily, the server-sig-algs extension.
Currently, we always try to authenticate RSA keys first with ssh-rsa (SHA-1) because otherwise certain servers are prone to misbehaving - see #1283 and related discussions. With the server-sig-algs extension implemented, we can know upfront which algorithms the server will accept and we can e.g. save a signature round-trip in the case that the server will not accept ssh-rsa.
There may be some more extensions worth supporting in https://github.com/openssh/openssh-portable/blob/master/PROTOCOL
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reading RFC 8308, especially extension negotiation and server-sig-algs, then compare the OpenSSH PROTOCOL reference linked in the issue. Trace SSH key exchange and public-key authentication entry points in SSH.NET and identify existing protocol-extension tests. Done means the client negotiates the extension and uses the advertised server signature algorithms, with coverage for the relevant behavior.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- csharp
- Domain
- networking, security
- Issue type
- Feature
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100