Tag Archives: EC2

Unable to connect over SSH to EC2 instance from Linux

Common issue which occurs when trying to connect to AWS EC2 instances from Linux machines is the following error:

WARNING: UNPROTECTED PRIVATE KEY PAIR

As you can see on the screenshot octal representation of pem file permissions is 0644 and it means that everyone has read-only access to the file while security best practice requires to limit access to private key files more strictly. This 0644 permission translates into RW for Owner, R for Group, and R for other/word (Everyone counterpart of Windows ACLs).

If you want to view file permissions in Linux shell you have 2 couple of commands for that ls -l %filename% and stat %filename% and the latter will show you octal permissions value as shown below:

Checking file permissions using ls -l and stat commands

Actually AWS EC2 console indicates recommended pem file permissions configuration and gives us a command to set them:

Command to ensue that your key is not publicly viewable

So just run this command and you will be able to connect (be sure running all the commands after switching directory to the one which contains your pem file and make sure that you use correct pem file name – AWS will give you command specific for EC2 instance and uses access key name based on selection you’ve made for specific EC2 instance).

Adjusting pem file permissions and connecting to EC2 instance over SSH

Although this is not a big problem and all the explanations/solutions are given to you by respective commands output and AWS console I just decided to jot this down in case someone will get stuck with this and switches to googling bypassing reading error messages and instructions šŸ™‚

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