enable firewall port 22 on ec2 server after disable it

Question

Step error: 1. sudo ufw enable 2. Command may disrupt existing ssh connections. Proceed with operation (y|n)? y 3. exit Before ssh again and can not access. On Security Group, port 22 is opening But firewall disable port 22. How to access server again?

Answer 1

You could use the following simplest way (user-data) to turn off the ufw then access the instance and edit your firewall.

1. stop the instance
2. Edit the user data to disable the ufw once and let you access the instance
3. start the instance

Following is the user data:

Content-Type: multipart/mixed; boundary="//"
MIME-Version: 1.0

--//
Content-Type: text/cloud-config; charset="us-ascii"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment; filename="cloud-config.txt"

#cloud-config
cloud_final_modules:
- [scripts-user, once]

--//
Content-Type: text/x-shellscript; charset="us-ascii"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment; filename="userdata.txt"

#!/bin/bash
sudo ufw disable
--//

Answer 2

At this point, there is nothing you can do to get back into the machine. It seems (from your comments) that ufw automatically starts and you have not added a rule to it to allow SSH traffic.

What you can do to recover data is

• shut down the EC2 instance,
• detach the EBS volume,
• launch a different EC2 instance,
• log into it,
• mount the EBS volume and
• copy the data to the new instance