005- SSH tunnels for 'kvm-host1' and 'kvm-host2'

References:

1) https://www.ssh.com/ssh/tunneling/example#sec-Local-Forwarding
2) https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/deployment_guide/s2-ssh-beyondshell-tcpip

Example #1 - Using Jumpstart Server:

Assuming the following network, diagram, you can access 'kvm-host1' shell directly using SSH tunnel using the following commands:

 


Fromat:

ssh -L <127 .0.0.1:local_port="">:<destination_server>:<destination_port>  USERNAME@<jumpstart_server>

Real Example:
from your local machine, as 'root' user:

[root@oc5748286004 ~]# hostname
oc5748286004.ibm.com

[root@oc5748286004 ~]# ssh -L 127.0.0.1:2222:192.168.75.170:22  ab@158.69.253.39

[root@oc5748286004 ~]# netstat -tunpenl | grep -e Proto -e 2222
Proto Recv-Q Send-Q Local Address           Foreign Address         State       User       Inode      PID/Program name    
tcp        0      0 127.0.0.1:2222          0.0.0.0:*               LISTEN      0          3879841    8468/ssh          

Now, SSH to '127.0.0.1' using port '2222', then you will access 'kvm-host1' using the opened SSH tunnel:

[root@oc5748286004 ~]# hostname
oc5748286004.ibm.com

[ab@oc5748286004 ~]$ ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no ab@127.0.0.1 -p 2222

Example #2 - Using Remote 'localhost':

Assuming the following network, diagram, 'base.ab.lab' accept HTTP connections ONLY via 'base.ab.lab' localhost:

[root@base ~]# hostname
base.lab

[root@base ~]# iptables -nvL INPUT | head -n3
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 DROP       tcp  --  *      *       158.69.253.39        0.0.0.0/0            tcp dpt:80

Now, from your local machine, create SSH tunnel that using '158.69.253.39' public IP address as a jumpstart serer to access 'base.ab.lab' localhost on port 80.
FORMAT

ssh -L <MY_LOCALHOST>:<LOCAL_PORT>:<REMOTE_LOCALHOST>:<REMOTE_PORT>  <USERNAME>@<REMOTE_PUBLIC_IP>

REAL EXAMPLE

[root@oc5748286004 ~]# hostname
oc5748286004.ibm.com

[root@oc5748286004 ~]# ssh -L 127.0.0.1:8080:localhost:80  ab@158.69.253.39

[ab@oc5748286004 ~]# hostname
oc5748286004.ibm.com

[ab@oc5748286004 ~]$ lynx --dump http://127.0.0.1:8080
   HTTP SERVER!

I created the following script to automate the above two examples:

https://github.com/abdurrahman84/BASH-real-examples/blob/master/ssh_tunnel.sh