Ssh – Modifying /etc/hosts to easily access a domain name (or ip address) for amazon EC2 instance

amazon ec2hostnamehosts-filessh

I previously added into my local(Mac OS x 10.6) /etc/hosts file my server's public ip something like this:

123.123.123.123 myServer

to allow me to ssh to myServer without having to remember the ip address of the server and worked fine (using shh public key) , like this:

ssh myServer1

However on Amazon EC2 instance I tried to do the same using the long public dns address provided and in /etc/hosts I added this:

ec2-23-23-23-23.compute-1.amazonaws.com myServer2

but when I try to ssh myServer2 says that the 'hostname cannot be resolved'

any ideas why this is not working? How can I make this work ?

The complete command I want to use is:

ssh -i key.pem user@ec2-23-23-23-23.compute-1.amazonaws.com

and I am trying to create a shortcut which might be something like this:

ssh -l username myServer2 or ssh -i key.pem -l username myServer2

any ideas?

UPDATE: I used alias instead which is easier:

Added this inside .bash_profile (MAC OS x)

alias myServer='ssh -i /path/to/key.pem user@ec2-23-23-23-23.compute-1.amazonaws.com'

(need to close and open terminal again or use source ~/.bash_profile )
Then ssh with just using myServer on command line
$ myServer

Best Answer

Instead of editing your hosts file, read about the SSH client configuration.

You can create host aliases in ~/.ssh/config. For example:

Host myServer2
     HostName ec2-23-23-23-23.compute-1.amazonaws.com
     UserName username

If you're only using SSH this will work fine. If you need to access other services, either set up DNS, or use port forwarding in SSH (with -L).

Related Solutions

Linux – Is it possible to alias a hostname in Linux

For those who don't have an account on the forums (or don't wish to login):

if your main issue is not to ping but to ssh, you can create/edit your ~/.ssh/config adding lines like these:

Host fakehost1
  Hostname real-hostname

Host fakehost2
  Hostname real-hostname2

Host fakehost3
  Hostname real-hostname3

Python CGI on Amazon AWS EC2 micro-instance — a how-to!

(Strange post, so hopefully this won't be as strange a reply).

On the subject of security flaws: it is considered general bad practice to store cgi-bin scripts within the document root of the web server. Even the W3C eludes to it under "Are compiled languages such as C safer ..." in their World Wide Web Security FAQ:

Consider the following scenario. For convenience's sake, you've decided to identify CGI scripts to the server using the .cgi extension. Later on, you need to make a small change to an interpreted CGI script. You open it up with the Emacs text editor and modify the script. Unfortunately the edit leaves a backup copy of the script source code lying around in the document tree. Although the remote user can't obtain the source code by fetching the script itself, he can now obtain the backup copy by blindly requesting the URL:
    http://your-site/a/path/your_script.cgi~
(This is another good reason to limit CGI scripts to cgi-bin and to make sure that cgi-bin is separate from the document root.)

This is not as significant a threat as the ability to write a file within the document root. However, an attacker could obtain the source code of the cgi, devise a directed attack against it, and use it as a stepping stone into the server.

To mitigate this, you can add the following lines to the lighttpd.conf (or some variation therein) to direct cgi-bin to a directory separate from the /var/www/lighttpd document root.

$HTTP["url"] =~ "/cgi-bin/" { cgi.assign = ( "" => "" ) }
alias.url = ( "/cgi-bin/" => "/usr/lib/cgi-bin/" )

This requires both the cgi and alias modules for lighttpd.

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