Fixing manufacturing points is likely one of the key duties of system and community directors. Actually, I’ve all the time discovered it to be one of the fascinating components of infrastructure engineering. Diving as deep as wanted into the issue at hand, not solely do you (ultimately) have the satisfaction of fixing the problem, you additionally study numerous issues alongside the best way, which you most likely wouldn’t have been uncovered to underneath regular circumstances.

Working programs definitely current such alternatives. Over time, they’ve grown ever extra complicated, forcing directors to grasp a zillion configuration information and settings. Though infrastructure as code and automation have enormously improved provisioning and managing servers, there’s all the time room for errors and breakdowns that forestall a system from beginning accurately. The listing is limitless: lacking {hardware} drivers, misconfigured file programs, invalid community configuration, incorrect permissions, and so forth. To make issues worse, many points can successfully lock directors out of a system, stopping them from logging in, diagnosing the issue and making use of the suitable repair. The one choice is to have an out-of-band connection to your servers, and though prospects might view the console output of an EC2 occasion, they couldn’t work together with it – till now.

At present, I’m extraordinarily completely happy to announce the EC2 Serial Console, a easy and safe approach to troubleshoot boot and community connectivity points by establishing a serial connection to your Amazon Elastic Compute Cloud (EC2) situations.

Introducing the EC2 Serial Console
EC2 Serial Console entry is out there for EC2 situations based mostly on the AWS Nitro System. It helps all main Linux distributions, FreeBSD, NetBSD, Microsoft Home windows, and VMWare.

With none want for a working community configuration, you may connect with an occasion utilizing both a browser-based shell within the AWS Administration Console, or an SSH connection to a managed console server. No want for an sshd server to be working in your occasion: the one requirement is that the root account has been assigned a password, as that is the one you’ll use to log in. Then, you may enter instructions as when you’ve got a keyboard and monitor immediately connected to one of many occasion’s serial ports.

As well as, you may set off working system particular procedures:

  • On Linux, you may set off a Magic SysRq command to generate a crash dump, kill processes, and so forth.
  • On Home windows, you may interrupt the boot course of, and boot in protected mode utilizing Emergency Administration Service (EMS) and Particular Admin Console (SAC).

Having access to an occasion’s console is a privileged operation that ought to be tightly managed, which is why EC2 Serial Console entry shouldn’t be permitted by default on the account stage. When you allow entry in your account, it applies to all situations on this account. Directors can even apply controls on the group stage because of Service Control Policies, and at occasion stage because of AWS Identity and Access Management (IAM) permissions. As you’ll count on, all communication with the EC2 Serial Console is encrypted, and we generate a singular key for every session.

Let’s do a fast demo with Linux. The method is comparable with different working programs.

Connecting to the EC2 Serial Console with the AWS Administration Console
First, I launch an Amazon Linux 2 occasion. Logging in to it, I resolve to mangle the community configuration for its Ethernet community interface (/and so forth/sysconfig/network-scripts/ifcfg-eth0), setting a very bogus static IP tackle. PLEASE don’t do that on a manufacturing occasion!

Then, I reboot the occasion. A number of seconds later, though the occasion is up and working within the EC2 console and port 22 is open in its Safety Group, I’m unable to hook up with it with SSH.

$ ssh -i ~/.ssh/mykey.pem [email protected]
ssh: connect with host port 22: Operation timed out

EC2 Serial Console to the rescue!

First, I want to permit console entry in my account. All it takes is ticking a field within the EC2 settings.

Enabling the console

Then, proper clicking on the occasion’s identify within the EC2 console, I choose Monitor and troubleshoot; then EC2 Serial Console.

This opens a brand new window confirming the occasion id and the serial port quantity to hook up with. I merely click on on Join.

This opens a brand new tab in my browser. Hitting Enter, I see the acquainted login immediate.

Amazon Linux 2
Kernel 4.14.225-168.357.amzn2.x86_64 on an x86_64
ip-172-31-67-148 login:

Logging in as root, I’m relieved to get a pleasant shell immediate.

Enabling Magic SysRq for this session (sysctl -w kernel.sysrq=1), I first listing out there instructions (CTRL-0 + h), after which ask for a reminiscence report (CTRL-0 + m). You possibly can click on on the picture beneath to get a bigger view.

Connecting to the console

Fairly cool! This may undoubtedly turn out to be useful to troubleshoot complicated points. No want for this right here: I shortly restore a sound configuration for the community interface, and I restart the community stack.

Making an attempt to hook up with the occasion once more, I can see that the issue is solved.

$ ssh -i ~/.ssh/mykey.pem [email protected]

__|   __|_  )
_|   (    / Amazon Linux 2 AMI
[[email protected] ~]$

Now, let me shortly present you the equal instructions utilizing the AWS command line interface.

Connecting to the EC2 Serial Console with the AWS CLI
That is equally easy. First, I ship the SSH public key for the occasion key pair to the serial console. Please ensure so as to add the file:// prefix.

$ aws ec2-instance-connect send-serial-console-ssh-public-key --instance-id i-003aecec198b537b0 --ssh-public-key file://~/.ssh/ --serial-port 0 --region us-east-1

Then, I ssh to the serial console, utilizing <occasion id>.port<port quantity> as person identify, and I’m greeted with a login immediate.

$ ssh -i ~/.ssh/mykey.pem [email protected]

Amazon Linux 2
Kernel 4.14.225-168.357.amzn2.x86_64 on an x86_64
ip-172-31-67-148 login:

As soon as I’ve logged in, Magic SysRq is out there, and I can set off it with ~B+command. I can even terminate the console session with ~..

Get Began with EC2 Serial Console
As you may see, the EC2 Serial Console makes it a lot simpler to debug and repair complicated boot and community points taking place in your EC2 situations. You can begin utilizing it right now within the following AWS areas, at no further value:

  • US East (N. Virginia), US West (Oregon), US East (Ohio)
  • Europe (Eire), Europe (Frankfurt)
  • Asia Pacific (Tokyo), Asia Pacific (Sydney), Asia Pacific (Singapore)

Please give it a strive, and tell us what you assume. We’re all the time trying ahead to your suggestions! You possibly can ship it by your typical AWS Help contacts, or on the AWS Forum for Amazon EC2.

– Julien



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