SSH connections with PBCL_SysLinuxShell_1 stopped working with FW2022

PLCnext Technology & PLCnext Controls
1

Hello,
i was using PBCL_SysLinuxShell_1 from PLCnextBase 1.4.1
The FB sends a command to reboot a device using SSH:
ssh -i /opt/plcnext/projects/RebootSsh/id_rsa_plcne.priv -o „UserKnownHostsFile=/dev/null“ -o „StrictHostKeyChecking=no“ -o „HostKeyAlgorithms=ssh-rsa“ root@192.168.1.1 reboot

This used to work correctly with FW2021.6 and FW2021.9 but it doesn 't work anymore with FW2022.0.3 and FW2022.0.4.

The output values are:

anyResult ''xDone FALSExError TRUEwDiagCode 16#C331wAddDiagCode 16#0002

that means "Timeout error to the PLCnextBaseServices server ", but I set diTimeout even to 40000 (40 s)

I used also another command:
ssh -i /opt/plcnext/projects/RebootSsh/id_rsa_plcne.priv -o „UserKnownHostsFile=/dev/null“ -o „StrictHostKeyChecking=no“ -o „HostKeyAlgorithms=ssh-rsa“ root@192.168.1.1 -q pwd
that normally would give back as anyResult the value „/root“, but now gives back „OK“, that doesn’t make any sense…

Does anyone know why this happens with new FW?
I found that with FW2022 the OpenSSH release was upgraded from 8.4p1 to 8.8p1

Thanks,
Marcello

P.S.: The private key „id_rsa_plcne.priv“ is the copy of the original key (created by admin), owned by plcnext_firmware :

admin@axcf2152:/opt/plcnext/projects/RebootSsh$ ls -l``-rw-rw---- 1 admin plcnext 2602 Apr 01 11:12 id_rsa.priv``-rw-r--r-- 1 admin plcnext 568 Apr 01 11:12 id_rsa.pub``-rw------- 1 plcnext_firmware plcnext 2602 Apr 01 12:18 id_rsa_plcne.priv

2

Thanks to ,
while doing some tests he suggested I’ve found the problem:

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

This release disables RSA signatures using the SHA-1 hash algorithm
by default.

So, after the command, the FB was stacked because SSH server asked for a password… It seems that the possible solutions are: Adding the option _-o „PubkeyAcceptedKeyTypes=+ssh-rsa“ _
1. to the ssh command (already tested, it works)
2. Create a new set of pub/priv keys, using something different than SHA-1

Bye,
Marcello

P.S.:
Even a simple SSH command from PLCnext terminal, with FW2022.0.3, doesn’t work as usual anymore:
admin@axcf2152:~$ ssh root@192.168.1.1
Unable to negotiate with 192.168.1.1 port 22: no matching host key type found. Their offer: ssh-rsa

it seems to be required to specify this option:
admin@axcf2152:~$ ssh -o "HostKeyAlgorithms=ssh-rsa" root@192.168.1.1

3

Now that the problem has been identified, I see that this change was mentioned in the release notes for firmware version 2022.0.3, although the „future firmware release“ it mentions seems to be the current firmware release.
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