Package: client
The client does not support chacha20 as I get this error when I try to connect to the X2Go server. I did harden my SSH configuration as guided by Mozzila https://infosec.mozilla.org/guidelines/openssh
When I use defaults it works fine. It seems that the library used by X2Go is missing some newer methods.
Config: server ssh config: KexAlgorithms curve25519-sha256@libssh.org ,ecdh-sha2-nistp521,ecdh-sha2-nistp384,ecdh-sha2-nistp256,diffie-hellman-group-exchange-sha256 Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com, aes128-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-ctr MACs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com, umac-128-etm@openssh.com,hmac-sha2-512,hmac-sha2-256,umac-128@openssh.com
Client sshd config: Client using default sshd config
or
HashKnownHosts yes HostKeyAlgorithms ssh-ed25519-cert-v01@openssh.com, ssh-rsa-cert-v01@openssh.com,ssh-ed25519,ssh-rsa, ecdsa-sha2-nistp521-cert-v01@openssh.com, ecdsa-sha2-nistp384-cert-v01@openssh.com, ecdsa-sha2-nistp256-cert-v01@openssh.com ,ecdsa-sha2-nistp521,ecdsa-sha2-nistp384,ecdsa-sha2-nistp256 KexAlgorithms curve25519-sha256@libssh.org ,ecdh-sha2-nistp521,ecdh-sha2-nistp384,ecdh-sha2-nistp256,diffie-hellman-group-exchange-sha256 MACs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com, umac-128-etm@openssh.com,hmac-sha2-512,hmac-sha2-256,umac-128@openssh.com Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com, aes128-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-ctr
Error: "kex error : no match for method mac algo client->server: server [ hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com, umac-128-etm@openssh.com,hmac-sha2-512,hmac-sha2-256,umac-128@openssh.com], client [hmac-sha1]"
or sometimes
"crypt_set_algorithms2: no crypto algorithm function found for chacha20-poly1305@openssh.com"
Let me know if I can provide more information.
Regards, *Danie de Jager*