(OK) Add a second NIC for a libvirt guest - virsh

https://kashyapc.fedorapeople.org/virt/add-network-card-in-guest.txt

Add a second NIC for a libvirt guest====================================Purpose: attach a new libvirt network to a live guest -- this takeseffect immediately, and the NIC will be persistent on further reboots.(0) Before adding a NIC, enumerate the network interfaces for vm1:    $ virsh domiflist vm1    Interface  Type       Source     Model       MAC    -------------------------------------------------------    vnet0      network    default    virtio      52:54:00:cd:58:29(1) Let's add a new NIC for the guest (the MAC address was chosen    randomly):    $ virsh attach-interface --domain vm1 --type network \        --source openstackvms --model virtio \        --mac 52:54:00:4b:73:5f --config --live    Interface attached successfully(2) Now again, enumerate the network interfaces for vm1, invoke the    below command on the host:    $ virsh domiflist vm1    Interface  Type       Source     Model       MAC    -------------------------------------------------------    vnet0      network    default    virtio      52:54:00:cd:58:29    vnet1      network    openstackvms virtio      52:54:00:4b:73:5f  (3) Inside the guest, you can see the second interface is now available:    $ ip a    1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default         link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00        inet 127.0.0.1/8 scope host lo           valid_lft forever preferred_lft forever        inet6 ::1/128 scope host            valid_lft forever preferred_lft forever    2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000        link/ether 52:54:00:cd:58:29 brd ff:ff:ff:ff:ff:ff        inet 192.168.122.50/24 brd 192.168.122.255 scope global dynamic eth0           valid_lft 2397sec preferred_lft 2397sec        inet6 fe80::5054:ff:fecd:5829/64 scope link            valid_lft forever preferred_lft forever    3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000        link/ether 52:54:00:4b:73:5f brd ff:ff:ff:ff:ff:ff        inet 192.169.142.233/24 brd 192.169.142.255 scope global dynamic eth1           valid_lft 3226sec preferred_lft 3226sec        inet6 fe80::5054:ff:fe4b:735f/64 scope link            valid_lft forever preferred_lft foreverTo detach the NIC-----------------(1) If you want to detach the network interface, this will take effect on    next boot of the guest:    $ virsh detach-interface --domain vm1 --type network \        --mac 52:53:00:4b:75:6f --config    Interface detached successfully(2) Reboot the guest, and enumerate the network interfaces for vm1:    $ virsh domiflist vm1    Interface  Type       Source     Model       MAC    -------------------------------------------------------    vnet0      network    default    virtio      52:54:00:cd:58:29(3) And, inside vm1, you can now see only see the interface for    associated with the default network:    $ ip a    1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default         link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00        inet 127.0.0.1/8 scope host lo           valid_lft forever preferred_lft forever        inet6 ::1/128 scope host            valid_lft forever preferred_lft forever    2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000        link/ether 52:54:00:cd:58:29 brd ff:ff:ff:ff:ff:ff        inet 192.168.122.50/24 brd 192.168.122.255 scope global dynamic eth0           valid_lft 3600sec preferred_lft 3600sec        inet6 fe80::5054:ff:fecd:5829/64 scope link            valid_lft forever preferred_lft foreverNOTES:  - While detaching, using the "--live" parameter is not recommended as    it might affect any existing network activities on the NIC to be    removed.  - If detaching the NIC doesn't go as expected or it still shows up, to    get the guest back to its previous networking state, edit the guest    XML:        $ virsh edit vm1        [. . .]            and remove the network interface attribute:       <interface type='network'>          <mac address='52:54:00:4b:74:6f'/>          <source network='testnw'/>          <model type='virtio'/>          <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>        </interface>