Re: curl SFTP transfer from Cygwin on Win10 to Ubuntu 18.04 fails with Unknown host key type: 1835008

[Brian Inglis <Brian.Inglis@SystematicSw.ab.ca>]

On 2021-05-13 22:40, Voris, Ben via Cygwin wrote:
> curl issue https://github.com/curl/curl/issues/7057 was closed with:
> "This seems to be purely a libssh2 issue and not a curl one."
> Curl reports "libssh2/1.7.0"
> On the same system, ssh reports " OpenSSH_8.5p1, OpenSSL 1.1.1f  31 Mar 2020"
> The curl code in https://github.com/curl/curl/blob/master/lib/vssh/libssh2.c has a number of defines to control what type of host keys it will accept, including LIBSSH2_KNOWNHOST_KEY_ED25519
> Was the curl built with this set?
> Details are in the curl issue, but here they are again.
> Here is the curl failure:
> : curl -vvv -s -T t.cpp sftp://bvoris@nucnuc/tmp/t2.cpp
> * STATE: INIT => CONNECT handle 0x800085338; line 1634 (connection #-5000)
> * Added connection 0. The cache now contains 1 members
> * STATE: CONNECT => RESOLVING handle 0x800085338; line 1680 (connection #0)
> * family0 == v4, family1 == v6
> *   Trying 192.168.1.5:22...
> * STATE: RESOLVING => CONNECTING handle 0x800085338; line 1762 (connection #0)
> * Connected to nucnuc (192.168.1.5) port 22 (#0)
> * STATE: CONNECTING => PROTOCONNECT handle 0x800085338; line 1825 (connection #0)
> * SFTP 0x8000847c8 state change from SSH_STOP to SSH_INIT
> * Found host nucnuc in /home/BVoris/.ssh/known_hosts
> * Unknown host key type: 1835008
> * SFTP 0x8000847c8 state change from SSH_INIT to SSH_SESSION_FREE
> * SFTP 0x8000847c8 state change from SSH_SESSION_FREE to SSH_STOP
> * multi_done
> * The cache now contains 0 members
> * SSH DISCONNECT starts now
> * SSH DISCONNECT is done
> * Closing connection 0
> The curl/libcurl version:
> curl 7.76.1 (x86_64-pc-cygwin) libcurl/7.76.1 OpenSSL/1.1.1f zlib/1.2.11 brotli/1.0.9 zstd/1.4.9 libidn2/2.2.0 libpsl/0.21.0 (+libidn2/2.0.4) libssh2/1.7.0 nghttp2/1.37.0
> Release-Date: 2021-04-14
> Protocols: dict file ftp ftps gopher gophers http https imap imaps ldap ldaps mqtt pop3 pop3s rtsp scp sftp smb smbs smtp smtps telnet tftp
> Features: alt-svc AsynchDNS brotli Debug GSS-API HTTP2 HTTPS-proxy IDN IPv6 Kerberos Largefile libz Metalink NTLM NTLM_WB PSL SPNEGO SSL TLS-SRP TrackMemory UnixSockets zstd
> The known_hosts entry from the client:
> nucnuc ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAICmjvQ5jehz5Jwt1PDGJBSgcXVhoMRnbn/E2p3srSK+c
> curl is run on CYGWIN_NT-10.0 3.2.0(0.340/5/3) 2021-03-29 08:42 x86_64 Cygwin
> The target system has:
> OpenSSH_7.6p1 Ubuntu-4ubuntu0.3, OpenSSL 1.0.2n 7 Dec 2017

Looks like it will need libssh2 1.9.0+.
The next version 1.9.1 is nearing release incorporating all the updated support
as well as all CVE and other patches.

I am working on a couple of build issues, with upstream, and also 32 bit x86 builds.

If I can get those resolved, I could adopt libssh2 (also hosted/supported @haxx.se
involving some of the same folks), releasing an update when the new libssh2 release
is available, and releasing an updated curl release 2 with the updated libssh2.

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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