add docs/posts/add-kvm-network-with-virsh.md

docs/posts/add-kvm-network-with-virsh.md

@@ -0,0 +1,114 @@
+---
+title: "Add KVM Network With Virsh"
+date: 2021-10-16
+draft: false
+tags: ["linux", "kvm", "libvirt", "virsh"]
+authors: ["trent"]
+post: 25
+---
+date: 2021-10-16
+
+## Introduction
+This is a short and sweet walk-through for how to create
+a new network for `libvirt` for `kvm`, from the command line,
+using `virsh`.
+
+## Name Resolution
+Let's start with name resolution.
+
+* Install `libnss-libvirt`:
+```shell
+apt install libnss-libvirt
+```
+
+* In `/etc/nsswitch.conf`, add `libvirt` to hosts key.
+```cfg
+# /etc/nsswitch.conf
+# change this
+...
+hosts:          files dns mymachines
+...
+# to this
+...
+hosts:          files libvirt dns mymachines
+...
+```
+
+## Starter XML
+You could dumpxml on the existing _default_ network:
+```shell
+virsh net-dumpxml default > foonet.xml
+```
+Then, edit foonet.xml:
+
+* remove the network uuid
+* change the network name to taste
+* remove the bridge mac
+* change the bridge name to taste
+* change the bridge ip address and dhcp range to taste
+
+```xml
+<!-- foonet.xml -->
+<network>
+  <name>foonet</name>
+  <forward mode='nat'>
+    <nat>
+      <port start='1024' end='65535'/>
+    </nat>
+  </forward>
+  <bridge name='virbr101' stp='on' delay='0'/>
+  <ip address='10.55.44.1' netmask='255.255.255.0'>
+    <dhcp>
+      <range start='10.55.44.2' end='10.55.44.254'/>
+    </dhcp>
+  </ip>
+</network>
+```
+
+## Define The Network
+With the above xml file: `virsh net-define foonet.xml`
+
+The network definition can now be found in `/etc/libvirt/qemu/networks/foonet.xml`
+```xml
+<!-- /etc/libvirt/qemu/networks/foonet.xml -->
+<!--
+WARNING: THIS IS AN AUTO-GENERATED FILE. CHANGES TO IT ARE LIKELY TO BE
+OVERWRITTEN AND LOST. Changes to this xml configuration should be made using:
+  virsh net-edit foonet
+or other application using the libvirt API.
+-->
+
+<network>
+  <name>foonet</name>
+  <uuid>e6e40bfc-d449-4043-924c-ca0f0edf4210</uuid>
+  <forward mode='nat'>
+    <nat>
+      <port start='1024' end='65535'/>
+    </nat>
+  </forward>
+  <bridge name='virbr111' stp='on' delay='0'/>
+  <mac address='52:54:00:49:a7:f8'/>
+  <ip address='10.55.44.1' netmask='255.255.255.0'>
+    <dhcp>
+      <range start='10.55.44.2' end='10.55.44.254'/>
+    </dhcp>
+  </ip>
+</network>
+```
+
+You could also start the network without defining it
+using `virsh net-create foonet.xml`.
+
+## Start/Stop
+* Start the network
+    * `virsh net-start foonet`
+* Stop the network
+    * `virsh net-destroy foonet`
+* Undefine the network
+    * `virsh net-undefine foonet`
+* Autostart the network
+    * `virsh net-autostart foonet`
+* Disable autostart for the network
+    * `virsh net-autostart foonet --disable`
+
+Tab completion is you friend!

mkdocs.yml

@@ -24,6 +24,7 @@ markdown_extensions:
 nav:
   - Home:
     - Home: index.md
+    - "Add KVM Network With Virsh": posts/add-kvm-network-with-virsh.md
     - "KVM On Arch": posts/kvm-on-arch.md
     - "RaspberryPi LTE-Failover Router With DNS Caching": posts/raspberrypi-lte-failover-router-with-dns-caching.md
     - "Flutter Integration Test Server in Debian 11 Nspawn Container": posts/debian-11-nspawn-flutter-integration-test-server.md
@@ -62,6 +63,7 @@ nav:
     - FreeCodeCampChallenges: https://trentspalmer.github.io/fcc-challenges/
     - DeviceLayout: https://trentpalmer.work/6a57bbe24d8244289610bf57533d6c6f/
   - Posts:
+    - "Add KVM Network With Virsh": posts/add-kvm-network-with-virsh.md
     - "KVM On Arch": posts/kvm-on-arch.md
     - "RaspberryPi LTE-Failover Router With DNS Caching": posts/raspberrypi-lte-failover-router-with-dns-caching.md
     - "Flutter Integration Test Server in Debian 11 Nspawn Container": posts/debian-11-nspawn-flutter-integration-test-server.md