Source: The Illustrated Network—How TCP/IP Works in a Modern Network by Walter Goralski (2009)


SSH never trusts the network. Even if hackers took over the entire network, all that can happen is that SSH is forced to disconnect. Hackers cannot decrypt, play back, or compromise data on the connection.

This is not to say that the SSH is perfect. Like any other tool, SSH is only as good as those setting it up and using it. For example, SSH does have an option for encryption type (none), but this is only to be used for testing purposes. (There is no real enforcement of this, of course.) And SSH does nothing to prevent someone who had gained access to the host another way (perhaps by sitting down in front of the unprotected host itself) from doing a lot of damage with root access. In that case, SSH is often the first target of a local hacker.

Why is it that in the first instance there is a definite article in front of SSH, but in the second instance as well as in other places above and below there isn't? What exactly is the reason behind placing it there in your opinion?

SSH is a network protocol (it's also the name of the popular Unix client application that implements that protocol) used for remote computer access that has replaced Telnet. The main reason SSH has replaced Telnet is that SSH makes communication over a public channel such as the Internet completely secure.

  • 1
    Since Secure Shell is a proper noun, you can use the definite article with it. However, this looks like sloppy editing since it is normally not used with the abbreviation.
    – Mick
    Nov 20, 2016 at 17:41
  • Erm... Are you expecting us to go to the trouble of figuring out what [the] SSH refers to? Presumably you already know, since you must have read this in some more complete context. Nov 20, 2016 at 17:42

2 Answers 2


In your passage

the SSH

is somewhat incorrect though understandable, it should simply be

This is not to say that SSH is perfect.

or possibly

This is not to say the SSH protocol is perfect.

Secure SHell is a communication protocol for connecting with a host through the command line.

It would be the same as referring to

TCP/IP is a data transport protocol.
ISP is your internet provider.

the article "the" is not used when referring to these acronyms.


It could be an editorial slip, but the writer seems to be making a distinction between SSH as a tool and SSH as configured by the user, and so he uses the article to refer to an instance of SSH.

If that is indeed what is going on here, there were clearer ways to have made the distinction than using the definite article. He might have written "That is not to say that every installation of SSH..."

  • To me it sounds like he really is talking about the SSH protocol and not tools (like programs or applications) that use that protocol. He's saying that SSH is not perfect as a protocol (there are problems with it). But network protocols can be thought of as tools that we use to help us do things. Nov 20, 2016 at 17:56
  • Read more closely. "Like any other tool, SSH is only as good as those setting it up and using it. For example, SSH does have an option for encryption type (none), but this is only to be used for testing purposes."
    – TimR
    Nov 20, 2016 at 17:59
  • So, in that part, is it the SSH client program or the SSH protocol that he's talking about? To me, it doesn't sound like he's talking about the program. SSH programs are just implementations of the SSH protocol. There's no point of talking about them because at the moment we're studying how the SSH protocol works. Nov 20, 2016 at 18:00
  • Well, the author is talking about both the protocol and individual installations, where it is possible, for example, to leave the encryption type set to "none". So, you may have SSH installed but have it configured to be useless.
    – TimR
    Nov 20, 2016 at 18:04
  • Okay. He first talks about how hackers will not be able to tap into your SSH-secured connection because SSH is so good at encrypting your network data. And then he goes on to say that "the" SSH (the same thing he talks about a few lines above, that is, the SSH protocol), despite the fact that no hacker will be able to ever hack it, is still not perfect. Why? Because the SSH protocol at the end of the day is just a tool. And if we don't use it wisely, there's little to be gained from the security it provides. Do you see what I'm saying? Nov 20, 2016 at 18:12

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