How to setup SSH access between Host and VirtualBox Guest VMs

1. Make sure you have SSH server running in your VM

For example in my Ubuntu
sgeevar@ubuntu-ws:~/share$ service ssh status
ssh start/running, process 1157

If you do not have it, install using:
sudo apt-get install openssh-server

2. Power off your VMs and go to VirtualBox
File > Preferences > Network > Host-only Networks

See if you already have an entry, if not create one.

3. Open your VMs settings
Settings > Network > Adapter 2

Check Enable Network Adapter
Attacked to: Host-only Adapter
(The entry you saw in step 2 will be automatically assigned to Name)

Save the changes and exit

4. Now open a terminal in your Host machine
Give ifconfig (ipconfig if Windows)

You should see a new entry corresponding to the host-only adapter we created
Note down the inet addr (in my case 192.168.56.1)

5. Now boot your virtual machine
sudo vim /etc/network/interfaces

Add these entries
auto eth1
iface eth1 inet static
address 192.168.56.56 #based on the address you noted in step 4
netmask 255.255.255.0

Save and exit

sudo ifup eth1

Thats all, now you should be able to connect to your VM via SSH (like putty)

username@ipaddress

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Try, g++ <filename> -std=c++11 -pthread