You are not logged in.

#1 2018-03-07 19:21:34

kazimir
Member
Registered: 2012-01-20
Posts: 72

x2go cannot connect to server kex error

It's been a while since I've used x2go and when I try to use it it fails to connect with the following key exchange error:

x2go-DEBUG-../src/sshmasterconnection.cpp:649> "Cannot connect to HOST:PORT" - "kex error : no match for method kex algos: server [curve25519-sha256@libssh.org,diffie-hellman-group-exchange-sha256], client [diffie-hellman-group14-sha1,diffie-hellman-group1-sha1]"
x2go-ERROR-2> "Connection error: Cannot connect to HOST:PORT: kex error : no match for method kex algos: server [curve25519-sha256@libssh.org,diffie-hellman-group-exchange-sha256], client [diffie-hellman-group14-sha1,diffie-hellman-group1-sha1]"

Connecting to the server via ssh cli work flawlessly.

I can't find relevant documentation about configuring x2go client to use the correct kex algo.

Offline

#2 2018-07-31 16:26:15

ezacaria
Member
Registered: 2007-12-10
Posts: 59

Re: x2go cannot connect to server kex error

First off, apologies if this qualifies as "necro-bumping" but the "Code of conduct" in the wiki does not set a guideline as to what is considered an "old thread". The thread being some months old does not feel old to me.

I found a similar issue in Krusader when using the kio-extras' SFTP plugin. The problem seems to occur when talking to an openssh server version 7.4.

Although the server advertises many key algorithms, the client is only listed as accepting two (same as in kazimir's post).

The same client works against SSH-2.0-OpenSSH_6.6.1 and SSH-2.0-OpenSSH_7.7, but fails against SSH-2.0-OpenSSH_7.4

I get the following:

log_kio_sftp: [ ssh_kex_select_methods ] ( 1 )  ssh_kex_select_methods: kex error : no match for method kex algos: 
server [curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256], 
client [diffie-hellman-group14-sha1,diffie-hellman-group1-sha1]

Furthermore, it makes no difference if the client's key is stored in the server's .ssh/authorized_keys2 or not.

The console ssh is working without any problem - as in Kazimir's case.

Any idea if this is some specific behaviour of Krusader (maybe libssh underneath?) against the server 7.4?

Offline

#3 2018-08-01 05:45:36

ezacaria
Member
Registered: 2007-12-10
Posts: 59

Re: x2go cannot connect to server kex error

The problem seems to relate to libssh. Since the usage of libssh appears to be behind the problem of Krusader rejecting cached known_hosts entries (if ssh has been done before using the kio slave), it seems that a better option is to use FISH instead.

This has been suggested in this other forum's post and is a valid workaround for file transfer.

Offline

Board footer

Powered by FluxBB