Troubleshooting Tip: 'No matching key exchange found'

xiaoj · ‎09-17-2023

Description

This article describes how to configure the SSH key exchange method to resolve an error stating no matching key exchange was found.

Scope

FortiGate.

Solution

Specify the key exchange algorithm in FortiGate to match the key exchange algorithm on the other side:

config system global
set strong-crypto {enable | disable}
set ssh-kex-algo <algo_1> [<algo_2> ... <algo_n>]
end

Note that the algorithm options are different based on the strong encryption setting.

strong-crypto enabled, ssh-kex-algo could be:

strong-crypto disabled, ssh-kex-algo could be:

Choose the proper SSH key exchange method. SSH from FortiGate to other devices should work.

Related article:
Troubleshooting Tip: SSH error 'No matching host key type found' without any offer.