SFTP - Couldn't agree a host key algorithm

Help & Support
1

Hello Support,

I try to connect via sftp to a standard Fedora 32 server with sftp-server enabled.
Bitvise SSH Client works with RSA/sha2-512, size: 3072 bits.
I'm using Dopus 12.24 x64 Build 7795 @ W10.

Dopus FTP gives me the following output:

Geöffnet wird Verbindung 192.168.1.6:22
Server version: SSH-2.0-OpenSSH_8.6
Using SSH protocol version 2
We claim version: SSH-2.0-PuTTY_Directory_Opus
Couldn't agree a host key algorithm (available: rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519)
SSH: Fatal: Couldn't agree a host key algorithm (available: rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519)
Verbindung geschlossen

Why Dopus does not support RSA/sha2-512?

Regards
Michael

1 Like
2

They use code from putty that is too old probably.

3

Why they dont update the code? In the current state (s)ftp is unusable...

4

Updating (or possibly completely replacing) that code is on our list, but not a simple task, and we have to finish some other work before we will get to it, unfortunately.

5

Run into this also recently, after upgrading one of my RPI Manjaro systems. I can no longer SSH into it from DOpus, though I can from other tools... :frowning:

Do we have a roadmap of when this is planned to be looked into?

6

Also just ran into this issue. Disappointing to read to it's a low priority item given SSH support is a paid extra and this has been known about for many years. Anyway if you control the server you can re-enable support for legacy clients like Opus by adding the following line to sshd_config.

HostKeyAlgorithms +ssh-rsa

1 Like
7

RSA was only removed from the default OpenSSH config for new installs in late September of this year.

https://www.openssh.com/txt/release-8.8

8

True Leo but they announced they were going to do that in February of 2020 (with 8.2), and the advice to switch to more modern algorithms was around a long time before that.

9

I am experiencing the same issue. Is there any workaround available?

10

I decided to use the suggested workaround (for my own server of course) from john_r (Oct 10) in this thread.

11

New DOpus user here (if you don't count the Amiga days)... Just bought DOpus including the paid FTP option, and the fact that SFTP doesn't work with current OpenSSH versions is disappointing. The store page should at least be updated to mention this, so that there's no surprise for new buyers like me.

It is also somewhat worrisome that security sensitive code that is sourced from upstream can't be easily updated.

2 Likes
12

I also just purchased DOpus with the advanced FTP option, and I'm pretty upset that I just spent 100$ and can't even use one of the key features that I specifically paid extra for. With no trial option for the advanced FTP plugin, I had no way of knowing that this feature wouldn't work until after dropping the money, and no updates on the state of the issue in 4 months. Gave it a test on the latest beta and the issue is still present. Very disappointing and frustrating.

13

This is on our list but we don't have an estimate for completion yet.

Note that Advanced FTP can definitely be trialled before purchase as part of the 60 day evaluation period.

14

We have added support for the elliptic curve algorithms in 12.26.3 beta.

2 Likes
15

Thank you! I hugely appreciate this being fixed. :slight_smile:

1 Like
16

Hi : )
I also pray to Allah to send some fix for "Couldn't agree a host key algorithm" ...

17

This should fix that. Have you tried it?

18

I'm sorry, I can't check. The problem happened when I tried connect to TrueNAS SCALE, but I switched my NAS to openmediavault and the problem went away : )

19

For this issue, there is still no fix?

Server version: SSH-2.0-OpenSSH_8.9p1 Ubuntu-3ubuntu0.1
Using SSH protocol version 2
We claim version: SSH-2.0-PuTTY_Directory_Opus
Couldn't agree a host key algorithm (available: rsa-sha2-512,rsa-sha2-256)
SSH: Fatal: Couldn't agree a host key algorithm (available: rsa-sha2-512,rsa-sha2-256)
Connection closed

It's running on a remote server...so I can't change anything!