Running ssh on Amazon EC2 instance on port other than 22

Question

I am not able to access Amazon EC2 instance via ssh as i am behind a firewall. So, i thought of running ssh on port other than 22, like 80 or 443.

I tried starting Amazon EC2 instance via Web Management Console with following 'user data':

#!/bin/bash -ex
perl -pi -e 's/^#?Port 22$/Port 80/' /etc/ssh/sshd_config
service sshd restart || service ssh restart

The idea being that the above script would execute on instance startup and switch ssh from port 22 to port 80. (Ref: http://alestic.com/2010/12/ec2-ssh-port-80)

But ssh is still not accessible on port 80. Apparently 'user data' script is not being executed on start up?

I can 'only' start stop instances via Web Management Console, not from command-line (being behind firewall)

Any ideas?

Answer 1

To connect to an AWS instance through ssh from a port different than default 22:

1. Open the security group of your instance so that it allows connections to that port from the source that you choose (0.0.0.0/0 for any source).

2. In your instance:

   • It is a new instance you could use an user-data script like this one:

   #!/bin/bash -ex perl -pi -e 's/^#?Port 22$/Port 443/' /etc/ssh/sshd_config service sshd restart || service ssh restart

Please note that this only works if you are launching a new instance:

User data scripts and cloud-init directives only run during the first boot cycle when an instance is launched.

• If it is not a new Instance, edit the /etc/ssh/sshd_config file adding/changing Port 22 to the port that you want (i.e: Port 443) to connect through ssh and then do service ssh restart and you should be done.

Note: I did this with an Ubuntu instance, with another Linux instances may be slightly different.

Answer 2

The amazon firewall blocks all ports other than 22. You first have to enable port 80/443/whatever.

HOWTO: Go to "security groups" -> click on the group you chose for your instance, then on the "Inbound" tab.

There you can add your ports.

EDIT: If by chance you also installed apache or some other webserver, port 80 will be used and cannot be used by sshd. I do not know which operating system is installed on your server, but maybe some webserver is already included?

Answer 3

Here is what I came up with to run sshd on 443 and 22 having rhel8 on ec2

1. make sure your security groups allow connection from your network/ip to the desired ports (in my case 22 and 443)

tcp 443 1.2.3.4/32 #allow access to 443 from IP 1.2.3.4
tcp 22 1.2.3.4/32 #allow access to 22 from IP 1.2.3.4

2. Login to the EC2 and

#install semanage with
sudo yum install -y policycoreutils-python-utils
#delete 443 from http ports
sudo semanage port -d -t http_port_t -p tcp 443
#add 443 to ssh ports
sudo semanage port -m -t ssh_port_t -p tcp 443

3. Edit /etc/ssh/sshd_config

Port 22
Port 443

4. Restart sshd

sudo service sshd restart