How to accept 'yes' from shell script "Are you sure you want to continue connecting (yes/no)?" using ssh. Without using StrictHostKeyChecking=no

Question

I'm using ssh command to remotely executing a shell script with -o **StrictHostKeyChecking=no ** option to bypass the authentification:

ssh -o StrictHostKeyChecking=no root@$IP '/test-script'

However, I'm using a sh shell that does not support the StrictHostKeyChecking=no option:

root:~ Jeff$ ssh StrictHostKeyChecking=no root@$IP '/test-script'

Could not create directory '/home/root/.ssh'.
The authenticity of host '192.168.186.1 (192.168.186.1)' can't be established.
ECDSA key fingerprint is SHA256:KOx9T7VeRy9dJ2ug+tfnlbnG/7Fm0I5Tl/ziTkE4JaE.
Are you sure you want to continue connecting (yes/no)?

All the -o option for ssh I have are:

ssh -o help
ssh: Available options:
ExitOnForwardFailure
UseSyslog

So is there any way I can prompt the 'yes' for the 'Are you sure you want to continue connecting (yes/no)?' question on the remote host?

I tried the following options but none of them worked

ssh -o StrictHostKeyChecking=no root@$IP '/test-script' | yes
yes | ssh StrictHostKeyChecking=no root@$IP '/test-script'
yes yes | ssh StrictHostKeyChecking=no root@$IP '/test-script'

Is there any way I can run the ssh remote command, read the prompt and find this question 'Are you sure you want to continue connecting (yes/no)?' and just enter yes?

Thank you

As I mentioned. I'm using a customized sh shell, that does not have ```-o StrictHostKeyChecking=no```. So sorry I can't use it :( — DavidKanes, Oct 20 '20 at 16:39
`StrictHostKeyChecking` is part of ssh, not sh! And I thought, you were missing `-o`. — Olaf Dietsche, Oct 20 '20 at 16:41
I see what you are saying. I meant to type ```-o``` but I forgot in the question. I will fix it — DavidKanes, Oct 20 '20 at 16:44
`ssh -o help ssh: Available options: ExitOnForwardFailure UseSyslog` These are all my avaliable options — DavidKanes, Oct 20 '20 at 16:46
Does this answer your question? [How do I prompt for Yes/No/Cancel input in a Linux shell script?](https://stackoverflow.com/questions/226703/how-do-i-prompt-for-yes-no-cancel-input-in-a-linux-shell-script) — Eugene Sh., Oct 20 '20 at 16:49

score 7 · Accepted Answer · answered Oct 20 '20 at 16:55

7

Assuming this is dropbear's ssh client.

From man dbclient

-y
Always accept hostkeys if they are unknown. If a hostkey mismatch occurs the connection will abort as normal.

This should be the dropbear equivalent to -o StrictHostKeyChecking=no.

answered Oct 20 '20 at 16:55

Olaf Dietsche

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WOW! It works great! Thank you! Did not know this spell – DavidKanes Oct 20 '20 at 16:59
@DavidKanes @Olaf it means if we edit in shell script to `ssh -y StrictHostKeyChecking=no` then prompt will not come at the time of debug/execute, isn't it? – Shahin P Apr 10 '23 at 11:31
1

@ShahinP No, these are two options from different ssh iplementations. `-y` belongs to dropbear, and `StrictHostKeyChecking` is from openssh. So it depends on which ssh you use. If it is openssh, use `-o StrictHostKeyChecking=no`, but if you have dropbear ssh client, you must use `-y` – Olaf Dietsche Apr 10 '23 at 11:46
@OlafDietsche In my script `ssh -o StrictHostKeyChecking=no` has not been mentioned but still i am getting prompt as yes/no when debug/run the shell script. – Shahin P Apr 11 '23 at 08:11

score 4 · Answer 2 · answered Jan 31 '23 at 09:47

Try -o StrictHostKeyChecking=accept-new. From the OpenSSH documentation on StrictHostKeyChecking:

If this flag is set to accept-new then ssh will automatically add new host keys to the user's known_hosts file, but will not permit connections to hosts with changed host keys.

ssh -o StrictHostKeyChecking=accept-new root@$IP '/test-script'

How to accept 'yes' from shell script "Are you sure you want to continue connecting (yes/no)?" using ssh. Without using StrictHostKeyChecking=no

2 Answers2