On the command line

On centos1, run the following:

[vagrant@centos1 ~]$ ssh -R 5353:127.0.0.1:22 192.168.33.11

Once connected to centos2, run the following:

[vagrant@centos2 ~]$ ssh 127.0.0.1 -p5353

You will probably be prompted to add a host key, and then be prompted for a password. We're connecting back to centos1, so provide the default Vagrant password.

You should be left at the centos1 command-line prompt:

vagrant@127.0.0.1's password: 
Last login: Thu Aug  9 12:29:56 2018 from 127.0.0.1
[vagrant@centos1 ~]$