[winswitch] Issue 270: Winswitch unable to connect over ssh from MS Windows to server running openssh 6.7

[Fabian Ritzmann]

Antoine Martin <antoine at nagafix.co.uk> schrieb am 11:38 Dienstag, 18.August 2015:

>On 18/08/15 14:49, Fabian Ritzmann wrote:
>> Hi,
>>
>> Since I am Trac-impaired (see my previous email to this mailing list), I am sending my comments via email. I was trying to connect from a MacBook with Winswitch 0.12.21-r5329 to an Arch Linux >server running OpenSSH 7.0p1. The SSH server is refusing the connection with this error message:
>>
>> sshd[20761]: fatal: Unable to negotiate with 10.128.133.54: no matching key exchange method found. Their offer: diffie-hellman-group-exchange-sha1,diffie-hellman-group1-sha1 [preauth]
>>
>> This looks like the same issue that this Windows user reported in <https://winswitch.org/trac/ticket/270> with OpenSSH 6.7. The suggested work-around in the issue is to reenable the DH SHA1 >key exchange, which I don't consider an option because it compromises security and exposes the host to the Logjam attack.
>>
>> I would hope that this issue gets more traction because it is an issue with any secure installation of OpenSSH and not specific to the Windows Winswitch client.
>Until this issue is fixed in Twisted conch (the SSH layer), there is
>absolutely nothing we can do about it.
>Here's the more recent upstream ticket:
>http://twistedmatrix.com/trac/ticket/7717


Thanks. Considering the age of that issue I better don't hold my breath. I guess I'll try creating a SSH tunnel manually and then connect the client to localhost.

Fabian