ssh : Unable to negotiate, no matching key exchange method found (Solaris 10)

Hi!

I'm investigating and trying to understand the root cause of the following behaviour.

target environment: Solaris 10 x86, CPU patchset 2018.01.11, kernel version: 150401-59

(client is my fedora workstation):

$ ssh lo-sol-jb4b739

Unable to negotiate with 172.16.117.200 port 22: no matching key exchange method found. Their offer: gss-group1-sha1-toWM5Slw5Ew8Mqkay+al2g==

(client is Solaris 11):

$ ssh lo-sol-jb4b739

Client and server could not agree on a key exchange algorithm:

  client: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1

  server: gss-group1-sha1-toWM5Slw5Ew8Mqkay+al2g==

but when I switch on the target side to cswopenssh, the connection can be established.