SSH to AWS EC2: ‘permissions 0644 are too open’ error

To connect to an EC2 instance over SSH, if the permissions on your .pem file are too broad then you’ll see this error:

Permissions 0644 for ‘keypair.pem’ are too open.

It is required that your private key files are NOT accessible by others.

This private key will be ignored.

chmod the .pem file to 0400 and then you should be good. This is described here.

Checklist for accessing an AWS EC2 instance with ssh

Quick checklist of items to check for enabling ssh instance into a running EC2 instance:

  • EC2 instance is started (check from AWS console)
  • From AWS console, check Security Group for the instance has an inbound rule for SSH – if only accessing remotely from your current IP, you can press ‘My IP’ to set your current public IP
  • From Network & Security, create a keypair and download the .pem file
  • Check the public DNS name for your EC2 instance from theĀ console
  • chmod 400 your .pem file, otherwise you’ll get an error that it’s publicly readable

Connect with:

ssh -i path-to-.pem-fileĀ

tmux useful commands

tmux is a great alternative to screen if you’re looking for multiple virtual sessions in one terminal window.

Useful commands:

Ctrl-b c : open new session

Ctrl-b n | p : cycle next / previous through sessions

Ctrl-b % | ” : split horizontally / vertically

Ctrl-b left | right | up |down : cycle back /forward through visible split windows (left/right if split horizontally, up/down if split vertically)

Using Putty SSH, if you’re not getting line characters for the splits, change session charset to UTF8.