How to use multiple ssh keys for one connection?

Georgiy List'ev

6/2/23, 11:00 PM

My organization has a server that requires two identity files simultaneously for one ssh connection. Just like this: ssh -i /first/key -i /second/key user@host And i am wondering how does it implemented? How to configure my own SSH server to make it require two identity files at the same time for one client?

0 + 0

ssh

Score:1

Ubuntu

matigo

6/3/23, 1:35 AM

This is controlled by the AuthenticationMethods section of the OpenSSH configuration. From the documentation, the most relevant section is this:

If the publickey method is listed more than once, sshd(8) verifies that keys that
have been used successfully are not reused for subsequent authentications.  For
example, "publickey,publickey" requires successful authentication using two
different public keys.

This is exactly what you are asking to do. So, with this in mind, let's get it done.

On the server ...

Create a new file for the AuthenticationMethods option:
```
sudo {editor of choice} /etc/ssh/sshd_config.d/two_key.conf
```
^{Note: Be sure to replace {editor of choice} with your editor of choice.}

Add this line to the file:

AuthenticationMethods publickey,publickey

Save the file and restart OpenSSH Server:
```
sudo service sshd restart 
```
Ensure both (or all) of your public keys are properly added to ~/.ssh/authorized_keys

Connect from another machine:

ssh -i /first/key -i /second/key user@host

That's all there is to it

0 + 0

Georgiy List'ev

6/3/23, 3:12 AM

Thanks! That is exactly I was looking for.

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: How to use multiple ssh keys for one connection?

TH: จะใช้คีย์ ssh หลายตัวสำหรับการเชื่อมต่อเดียวได้อย่างไร

RO: Cum să utilizați mai multe chei ssh pentru o singură conexiune?

RU: Как использовать несколько ключей ssh для одного соединения?

VI: Làm cách nào để sử dụng nhiều khóa ssh cho một kết nối?

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