16.8. Configuring the passt user-space connection

Procedure

1. Open the XML configuration of the VM on which you want to use a passt connection. For example:

   # virsh edit <testguest1>

2. In the <devices> section, add an <interface type='user'> element that uses passt as its backend type.

   For example, the following configuration sets up a passt connection that uses addresses and routes copied from the host interface associated with the first default route:

   <devices>
     [...]
     <interface type='user'>
       <backend type='passt'/>
     </interface>
   </devices>

   Optionally, when using passt, you can specify multiple <portForward> elements to forward incoming network traffic for the host to this VM interface. You can also customize interface IP addresses. For example:

   <devices>
     [...]
     <interface type='user'>
       <backend type='passt'/>
       <mac address="52:54:00:98:d8:b7"/>
       <source dev='eth0'/>
       <ip family='ipv4' address='192.0.2.1' prefix='24'/>
       <ip family='ipv6' address='::ffff:c000:201'/>
       <portForward proto='tcp'>
         <range start='2022' to='22'/>
       </portForward>
       <portForward proto='udp' address='1.2.3.4'>
          <range start='5000' end='5020' to='6000'/>
          <range start='5010' end='5015' exclude='yes'/>
       </portForward>
       <portForward proto='tcp' address='2001:db8:ac10:fd01::1:10' dev='eth0'>
         <range start='8080'/>
         <range start='4433' to='3444'/>
       </portForward>
     </interface>
   </devices>

   This example configuration sets up a passt connection with the following parameters:

   • The VM copies the network routes for forwarding traffic from the eth0 host interface.
   • The interface MAC is set to 52:54:00:98:d8:b7. If unset, a random one will be generated.
   • The IPv4 address is set to 192.0.2.1/24, and the IPv6 address is set to ::ffff:c000:201.
   • The TCP port 2022 on the host forwards its network traffic to port 22 on the VM.
   • The TCP address 2001:db8:ac10:fd01::1:10 on host interface eth0 and port 8080 forwards its network traffic to port 8080 on the VM. Port 4433 forwards to port 3444 on the VM.
   • The UDP address 1.2.3.4 and ports 5000 - 5009 and 5016 - 5020 on the host forward their network traffic to ports 6000 - 6009 and 6016 - 6020 on the VM.
3. Save the XML configuration.