How can I make it so that a block of text looks like a code block (with a grey background and mono-space font)?

Example:

# The primary network interface
auto eth1
iface eth1 inet dhcp

How can I make it so this,

The primary network interface

auto eth1 iface eth1 inet dhcp

looks the same as it appears on the monitor, like this:

# The primary network interface
auto eth1
iface eth1 inet dhcp

How can I make it so this,

# The primary network interface
auto eth1
iface eth1 inet dhcp

looks the same as it appears on the monitor.

How can I make it so that a block of text looks like a code block (with a grey background and mono-space font)?

Example:

# The primary network interface
auto eth1
iface eth1 inet dhcp