Set up SSH connections without password in just 3 steps

Hello,

Here you will see how to connect to a PC remotely by SSH just entering the password the first time, then even if we restart both computers, we will not be asked for the password again.

But, let's first see a brief explanation about what it is SSH:

SSH it is a protocol, a means of communication between two computers. It allows us to manage a team remotely. When we access another computer by SSH, the command that we enter in that terminal will be executed on the other computer, in this way we manage / control it.

Everything that is transmitted by SSH, it is encrypted and with a considerably good security.

Now, we will see how in just three steps we will configure PC # 1 to access PC # 2 without entering password:

We have the following situation:

PC # 1 - » You want to connect to PC # 2, without having to enter a password every time you try to connect to this other PC.

PC # 2 - » You have the SSH server installed. This is the one PC # 1 will connect, and will do so without entering a password. On this PC there is a user named root.

Let us begin…

1. En PC # 1 we write the following:

• ssh-keygen -b 4096 -t rsa

This will generate a public key. In order not to get too confused with "public and private keys", I will explain it very simply.

Suppose you have two keys to your house in your pocket, one you give to your girlfriend since you live together, and with the other you are left alone, you do not give it to anyone. Well, that key that you gave your girlfriend will allow her to enter your house without telling you, without asking your permission, right? that is a public key, a "key" that allows one PC to access another without having to ask for your permission (that is, without entering username + password)

When they put that command, that will appear:

2. Just press [enter], a second later we press again [enter], and a second later we press once more [enter]. I mean, we would press [enter] a total of three (3) times, we only press it ... we do not write anything : )

When we do this, something very similar to the following will appear:

Ready, we already have the public key ... now we need to give it to whoever we want (like the example, give it to our girlfriend haha)

What we want is that PC # 1 connect to PC # 2already in PC # 1 we did all of the above, in PC # 2 We have not done anything. Good, PC # 2 has an IP address for example 10.10.0.5.

3. We put in PC # 1 following:

• ssh-copy-id root@10.10.0.5

What this does is simply give you the public key of PC # 1 a PC # 2, that is, it gives to PC # 2 the public key of PC # 1While PC # 1 he keeps his private key, you know; that key that is not given to anyone. It is important not to make mistakes with the user, that is, if the user “root"It does not exist in PC # 2 will give us an error, it is important to be clear in which user we will use for this, in addition to the fact that that user with which we configure access without password, will be the same with which we will have to access in the future. Once this is done it should look like this:

In the previous step, they must put the user's password in PC # 2.

And voila ... everything is configured 😀

As well it appears to us in the terminal, let's test if everything really worked 100% OK. To test, we put:

• ssh root@10.10.0.5

If they want to access another computer also without always entering a password (PC # 3 for example), we simply give it our public key and that's it, that is, once we have done the step #1 y #2 we won't have to do it anymore. If we want to access PC # 3 for example, which has by IP 10.10.99.156 we just put:

• ssh root@10.10.99.156

So far the tutorial.

Explain that the security level when we talk about SSH is really high, the metaphor with which I explained some steps (giving the key to our girlfriend) may not be the most appropriate haha, since our girlfriend could give the key to someone else. When we talk about SSH, the security principles are easy to explain, when we try to access our computer (PC # 1) checks if in PC # 2 there is a public key of our computer (in this case there is, because we configure it that way), then, if there is one, it is simple, check if that public key is identically the same as our private key we didn't give it to anyone). If the keys are identical it allows us to access, otherwise and as a security measure, it does not allow us to remotely access the other computer.

So now you know ... giving our girlfriend the house key is not the safest thing, but sharing keys and accessing another computer remotely via SSH is safe ^ _ ^

Doubts or questions, complaints or suggestions let me know.

Greetings all.