If your corporate firewall does not allow ssh to EC2 instances due to blocked port 22 you can follow below workaround temporarily to ssh to EC2 instances.
Essentially you need to change the sshd
configuration to use port 80
which is typically open in most firewalls to allow http access.
Step 1: Launch a new EC2 instance
Step 2: On "3. Configure Instance" step, expand the "Advanced Details" section and put the below code
#!/bin/bash -ex
perl -pi -e 's/^#?Port 22$/Port 80/' /etc/ssh/sshd_config
service sshd restart || service ssh restart
Step 3: Launch the instance
Step 4: After successful startup, use the below ssh command to connect to this instance
ssh -p 80 -i "YOURKEYPAIR.pem" ec2-user@IPADDRESS
Inspired by: https://alestic.com/2010/12/ec2-ssh-port-80/