Enable X11 forwarding after Sudo SSH session for AWS EC2 Linux instance
Working with a secure environment presents some challenges and this post will demonstrate how to overcome one of the challenges. Prerequisites: Configuration for X-Windows must have been completed. Scenario: From laptop, connect to dinh@host, then connect to ssh ec2-user, then sudo su - oracle.
### Connect to AWS EC2 instance [dinh@securehost ~]$ ssh -X ec2-user@ipaddress Last login: Fri Dec 7 14:41:41 2018 from gw.ca.adm.pythian.com __| __|_ ) _| ( / Amazon Linux AMI ___|\___|___| https://aws.amazon.com/amazon-linux-ami/2018.03-release-notes/ 13 package(s) needed for security, out of 16 available Run "sudo yum update" to apply all updates. ### Test xclock works from ec2-user [ec2-user@ipaddress ~]$ xclock Warning: Missing charsets in String to FontSet conversion ^C ### Show all magic cookie [ec2-user@ipaddress ~]$ xauth list ipaddress/unix:12 MIT-MAGIC-COOKIE-1 7e53e7600ff4177d7bbc66bde0a1b1ca ipaddress/unix:11 MIT-MAGIC-COOKIE-1 e3d1a8915484c929ef3e809b047e6352 ipaddress/unix:10 MIT-MAGIC-COOKIE-1 07b3de3093cef835c19239ea952231b7 ### Show DISPLAY variable [ec2-user@ipaddress ~]$ env|grep DISPLAY DISPLAY=localhost:10.0 ### Create /tmp/xauth based on current DISPLAY variable [ec2-user@ipaddress ~]$ xauth list | grep unix`echo $DISPLAY | cut -c10-12` > /tmp/xauth [ec2-user@ipaddress ~]$ ll /tmp/xauth ; cat /tmp/xauth -rw-rw-r-- 1 ec2-user ec2-user 78 Dec 7 14:47 /tmp/xauth ipaddress/unix:10 MIT-MAGIC-COOKIE-1 07b3de3093cef835c19239ea952231b7 ### Sudo to oracle [ec2-user@ipaddress ~]$ sudo su - oracle Last login: Fri Dec 7 14:43:12 UTC 2018 on pts/0 ### Add and Verify xauth [oracle@ipaddress ~]$ xauth add `cat /tmp/xauth` [oracle@ipaddress ~]$ xauth list ipaddress/unix:10 MIT-MAGIC-COOKIE-1 07b3de3093cef835c19239ea952231b7 ### Verify and Add DISPLAY variable [oracle@ipaddress ~]$ env|grep DISPLAY [oracle@ipaddress ~]$ export DISPLAY=localhost:10.0 ### Test xclock works from oracle [oracle@ipaddress ~]$ xclock Warning: Missing charsets in String to FontSet conversion ^C [oracle@ipaddress ~]$ ### Example of failed xclock [oracle@ipaddress ~]$ xclock Error: Can't open display: [oracle@ipaddress ~]$ xclock
