Unless specified otherwise in `Vagrantfile`, the IP address of the host (the computer running Vagrant) from the perspective of the guest
(the VM being run by Vagrant) is: **_`10.0.2.2`_**

If that IP address doesn't work, then examination of `Vagrantfile` should reveal directives that changed it from its default value.

If an IP address can't be found in `Vagrantfile`, then the following command will probably reveal it:

```sh
route -A inet
```

For example, the output may be:

```text
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         10.0.2.2        0.0.0.0         UG    0      0        0 eth0
10.0.2.0        *               255.255.255.0   U     0      0        0 eth0
192.168.33.0    *               255.255.255.0   U     0      0        0 eth1
```

The desired IP address is the `Gateway` address of the `default` destination, which in this case is **_`10.0.2.2`_**.