SSH Host Key fingerprint does not match pattern – C# :: Support Forum

tsnik
Joined:: 2014-05-08
Posts:: 2
Location:: UK

SSH Host Key fingerprint does not match pattern – C#

2014-05-08 16:51

Hi,

I am trying to connect to an FTP site running explicit FTP over TLS, but the script trips over the Host Key fingerprint:

SessionOptions sessionOptions = new SessionOptions
{
    Protocol = WinSCP.Protocol.Ftp,
    FtpSecure = FtpSecure.ExplicitTls,
    HostName = "xxxxxxxxxxxxxxxxx",
    UserName = "xxxxxxxx",
    Password = "xxxxxxxx",
    SshHostKeyFingerprint = "ssh-rsa 2048 bb:9c:4c:05:f8:25:2b:8f:80:a3:75:b7:94:5c:ea:9f:fc:b2:12:18"
};

This is the information from the FTP site:

Remote system = UNIX Type: L8
File transfer protocol = FTP
Cryptographic protocol = TLS Explicit encryption, TLSv1
Encryption algorithm = TLSv1/SSLv3: IDEA-CBC-SHA, 2048 bit RSA
Compression = No
------------------------------------------------------------
Certificate fingerprint
bb:9c:4c:05:f8:25:2b:8f:80:a3:75:b7:94:5c:ea:9f:fc:b2:12:18
------------------------------------------------------------
Can change permissions = Yes
Can change owner/group = No
Can execute arbitrary command = Protocol commands only
Can create symlink/hardlink = No/No
Can lookup user groups = No
Can duplicate remote files = No
Can check available space = No
Can calculate file checksum = No
Native text (ASCII) mode transfers = No
------------------------------------------------------------

The additional information shows Fingerprint (SHA1):

bb:9c:4c:05:f8:25:2b:8f:80:a3:75:b7:94:5c:ea:9f:fc:b2:12:18

On attempting to connect I get the following error:

SSH host key fingerprint \"ssh-rsa 2048 bb:9c:4c:05:f8:25:2b:8f:80:a3:75:b7:94:5c:ea:9f:fc:b2:12:18\" does not match pattern /(ssh-rsa |ssh-dss )?\\d+ ([0-9a-f]{2}:){15}[0-9a-f]{2}(;(ssh-rsa |ssh-dss )?\\d+ ([0-9a-f]{2}:){15}[0-9a-f]{2})*/

Can anyone point me in the right direction?

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tsnik
Joined:: 2014-05-08
Posts:: 2
Location:: UK

SSH Host Key fingerprint does not patch pattern - c#

2014-05-08 17:48

I have located the problem. It was to do with the length of the Host Key, which I compared with another site that is working. I shortened the key and after a few more tests (I had a Peer certificate rejected), I got it to work.

Here is the amended section:

SessionOptions sessionOptions = new SessionOptions
{
    Protocol = Protocol.Ftp,
    FtpSecure = FtpSecure.ExplicitSsl,
    HostName = "xxxxxxxxxxxxxxxxxxx",
    UserName = "xxxxxxxx",
    Password = "xxxxxxxx",
    GiveUpSecurityAndAcceptAnyTlsHostCertificate = true
};

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martin◆ Site Admin
Joined:: 2002-12-10
Posts:: 41,441
Location:: Prague, Czechia

Re: SSH Host Key fingerprint does not patch pattern - c#

2014-05-09

The SessionOptions.SshHostKeyFingerprint is for SSH sessions, not for FTP over TLS/SSL. That also explains why the fingerprint have a different length.

See https://winscp.net/eng/docs/message_key_fingerprint_does_not_match

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SSH Host Key fingerprint does not match pattern – C#