Mastering Linux Security and Hardening, Second Edition by Donald A. Tevault

Author:Donald A. Tevault [Donald A. Tevault]
Language: eng
Format: epub
Tags: COM046070 - COMPUTERS / Operating Systems / Linux, COM043050 - COMPUTERS / Security / Networking, COM043040 - COMPUTERS / Networking / Network Protocols
Publisher: Packt Publishing
Published: 2020-02-20T12:41:39+00:00

To set up key-exchange authentication, use PuTTYgen to create the key pair. The only slight catch is that you'll have to transfer the public key to the server by manually copying and pasting the key into the server's authorized_keys file:

I've given you the basics about PuTTY. You can read the PuTTY manual to get the nitty-gritty details.

Okay — I think that that about wraps things up for our discussion of the Secure Shell suite.

Summary

In this chapter, we've seen that a default configuration of Secure Shell isn't as secure as we'd like it to be, and we've seen what to do about it. We've looked at how to set up key-based authentication, and we've looked at lots of different options that can lock down the SSH server. We also looked at how to disable weak encryption algorithms, and at how the new system-wide crypto policies on RHEL 8/CentOS 8 make doing that really easy. Along the way, we looked at setting up access controls, and at creating different configurations for different users, groups, and hosts. After demoing how to confine SFTP users to their own home directories, we used SSHFS to share a remote directory. We wrapped up this chapter by presenting a handy way to log into our Linux servers from a Windows desktop machine.

Conspicuous by their absence are a couple of technologies that you may have seen recommended elsewhere. Port knocking and Fail2Ban are two popular technologies that can help control access to an SSH server. However, they're only needed if you allow password-based authentication to your SSH server. If you set up key-based authentication, as I've shown you here, you won't need the added complexity of those other solutions.

In the next chapter, we'll take an in-depth look at the subject of discretionary access control. I'll see you there.

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