SFTP Connection Issue using UiPath.FTP.Activities

[Gerard_McNamara_Ged]

Hi,

I have an automation that is using UiPath.FTP.Activities version 2.3.0 in a Windows Legacy automation. This automation establishes a connection to an SFTP server using a certificate and password.

When this was setup I had to convert the ppk certificate to a PEM file using the process decribed in many over forum posts and this has worked without an issue since 2021.

Recently, the SFTP server owners have appled some changes to remove some ‘legacy security options’ which they are unwilling to share with me.

Subsequently, the automation is no longer able to establish a connection with the message that the established connection has been terminated by the server.

I have WinSCP installed and I haven’t updated it for several years either (I installed it when I was creating the automation) and when I was trying to connect via this mechanism I was receiving this error:

Initially I reported this to the SFTP server owners as I thought that they had changed my password/revoked my certificate etc but they informed me that I was trying to connect with an out of date client and I needed to update it. When I updated WinSCP to the latest version I was able to connect without any issues.

My question is, I suspect that the reason I cannot connect with the activity is because something it is using is out of date. I did notice that the SSH.NET version it is using if 2020.0.1 and there are several newer versions since then.

Does anyone know what options I have available to me (other than ask the server owner to reactivate the settings they deactivated - server owner is SAP so I highly doubt they will switch back on anything that makes them more insecure)

[ABHIMANYU_THITE1 (ABHIMANYU THITE)]

Hi @Gerard_McNamara_Ged
it’s related to the negotiation of the encryption algorithms between the client and the server. Check client and server are using up-to-date software versions.

Check if the SSH client or server is configured to use algorithms that are not supported by the other party. For example, if the server is configured to use a specific key exchange algorithm that the client does not support, the negotiation will fail.

[McDonalds (Mcd)]

You could also skip using the FTP activity and invoke VB code after installing the winscp nuget package and importing in the studio

Martin has put out a vb sample in his forums if you want to read up in more detail about it,
https://winscp.net/eng/docs/library_session_listdirectory#example

[Gerard_McNamara_Ged]

Thankyou for this - it is exactly what I am thinking and will solve the problem.

I am a little annoyed that the UiPath Activity is not being kept up to date with respect to ensuring it can handle the current key algorithms as it is likely the security aware companies will undertake these tasks of disabling the old ones as they are no longer secure