CHAPTER 15

Managing Host Networking

7 sections · 13 min read · SimpleVM 10.1

This chapter explains how to view and manage networking on the SimpleVM host itself — the physical interfaces the host uses to reach the network, the IP address that keeps the management interface reachable, the DNS and hostname settings the host relies on, and the bridges that let virtual machines appear directly on the same network as the host. Host networking is managed from the Networking page under System, and it is a different task from managing the virtual networks that VMs attach to. The distinction matters at every step: host networking governs the host’s own connectivity, while a virtual network governs how VMs connect. Because the page you change is often the same page you are reading it through, the single habit that keeps host networking safe is to confirm which interface is carrying management traffic — and to have a way back to the host — before you change anything.

Cross-reference: For signing in to the management interface, see Section 6.5, Sign In with Administrative Access. For the networks VMs attach to, see Chapter 14, Managing Virtual Networks; for attaching a VM’s interface to a network, see Section 10.2, Attaching VMs to Virtual Networks. For the host firewall, its zones, and allowed services, see Chapter 16, Firewall and Security Settings. For running recovery commands from the browser, see Section 19.4, Web Terminal Overview. For step-by-step network diagnosis, see Section 25.6, Network Issues.

This chapter at a glance. The sections below move from understanding and observing host networking to changing it safely:

• Understand host networking — what host networking is and how it differs from virtual networks (Section 15.1).
• Observe before you change — view the host interfaces (Section 15.2) and read the usage graphs (Section 15.3).
• Change addressing — set an interface to automatic or manual addressing, with a way back (Section 15.4).
• Bridge networking — put VMs on the same physical network as the host (Section 15.5).
• DNS and hostname — keep name resolution and host identity correct (Section 15.6).
• Troubleshoot — work host network problems layer by layer (Section 15.7).

15.1 Host Network Overview

Overview

Host networking is the network configuration of the SimpleVM host itself: the physical interface or bridge the host uses to reach the network, the host’s IP address, its DNS and hostname settings, and any bridge interfaces that connect virtual machines directly to the host’s network. It is managed from the Networking page (System > Networking, URL /network), which is a different place from the Networks page where virtual networks are managed. A SimpleVM host typically uses host networking in three ways:

• Management networking — the path used to reach the management interface, the web terminal, software updates, and administrative tools.
• Virtual machine networking — the path VMs use, which may be the default NAT network, a custom virtual network, or a host bridge, depending on the design. See Chapter 14, Managing Virtual Networks.
• Bridge networking — a host configuration that lets VMs share the host’s layer-2 network, so a VM can receive an address from the same upstream network as other physical servers (Section 15.5).

Host networking and virtual networks

Host networking and virtual networks are related but separate tasks. Use Chapter 14, Managing Virtual Networks when you need to create or change a virtual network for VM traffic — for example, the default NAT network on virbr0. Use this chapter when you need to change the host’s own interfaces, IP addressing, DNS settings, host bridges, or physical NIC configuration. A virtual network can be reconfigured without touching the host’s connectivity; a host network change can affect the host, the management interface, and any VM that depends on a host bridge at the same time.

Confirmed reference interfaces

The reference build shows the following host interfaces on the Networking page. Interface names and addresses are environment-specific; use this table to recognize the kinds of entries you will see, not as values to reproduce.

Because both bridge0 (10.0.0.142) and eno1 (10.0.0.52) are addressed on the management subnet, the management address is best documented as the URL shown on the host console rather than a single fixed IP. See Section 6.3, Management URLs.

15.2 Viewing Network Interfaces

Overview

The Networking page shows the active host interfaces, their assigned IP addresses, transmit and receive activity, the host firewall status, and the actions available for adding interfaces. This is the safest place to begin, because it lets you confirm what the host is using before you change anything.

Before you begin

• You are signed in to the SimpleVM management interface with administrative access. See Section 6.5, Sign In with Administrative Access.

Procedure

1. In the left-navigation menu, under System, open Networking.
2. Review the Transmitting and Receiving graphs to confirm recent network activity.
3. In the Interfaces table, review each interface’s Name, IP address, Sending, and Receiving values.
4. Identify which interface is carrying management traffic before making any change. In most deployments this is the interface that holds the host’s management IP address — in the reference build, the bridge0 interface.

What to look for

• Interface name — the system name of the device or bridge, such as a physical Ethernet adapter (eno1), a bridge (bridge0), or a libvirt-managed device (virbr0).
• IP address — the address assigned to the interface, set statically or by DHCP. An interface may show “Not available” when it is present but not currently active.
• Sending and receiving — traffic moving through the interface. Active traffic helps confirm which interface is in use, but a quiet interface is not necessarily unused.
• Firewall status — the host firewall state and a link to the firewall zones. Firewall changes are covered in Chapter 16, Firewall and Security Settings.

15.3 Network Usage Graphs

Overview

The network usage graphs give a quick view of transmit and receive activity in Mbps over the selected time range. They confirm that the host is communicating and help you spot spikes, drops, and periods of unexpected activity before you start changing settings.

Procedure

1. Open System > Networking.
2. Use the time-range control near the top of the page to set the graph window.
3. Review the Transmitting graph for outbound traffic from the host.
4. Review the Receiving graph for inbound traffic to the host.
5. Use the refresh or navigation control to inspect the time window shown.

Interpreting the graphs

• Steady traffic is normal on a host running active VMs.
• A sudden drop can indicate a disconnected interface, an upstream switch problem, or a VM or network-service outage.
• A sudden increase can indicate a backup, a VM migration, a file transfer, an update download, or unexpected workload behavior.
• If a graph shows activity but a VM cannot communicate, check both host networking and the VM’s network attachment. See Section 10.4, Verifying VM Connectivity.

15.4 Interface Configuration

Overview

Interface configuration controls how the host connects to the physical network. Common changes are assigning a static IP address, switching between automatic (DHCP) and manual addressing, setting DNS servers, enabling or disabling an interface, and preparing an interface to become part of a bridge. Because the management interface usually rides on one of these interfaces, plan the change so you can recover the host if it becomes unreachable.

Before you begin

• Confirm the correct IP address, subnet prefix, gateway, DNS servers, and DNS search domain for the host.
• Confirm which physical interface is connected to the correct switch port or VLAN.
• Make sure you have console or out-of-band access in case the management interface becomes unreachable.
• If the host is part of a cluster, confirm whether the change affects migration, storage, cluster communication, or high availability before you continue. See Section 22.6, Networking Requirements.

Procedure

1. Open System > Networking.
2. In the Interfaces table, select the interface you want to configure.
3. Review the current addresses, routes, and DNS settings, and record them so you can restore them if needed.
4. Select the edit control for the protocol or address settings.
5. Choose Automatic for DHCP addressing or Manual for a static address.
6. For manual addressing, enter the IP address, subnet prefix, gateway, DNS servers, and DNS search domain for your environment.
7. Apply the change with Apply or the equivalent save action.
8. Wait for the network service to apply the configuration. If the browser disconnects, reconnect to the new management address.

Verification

• The interface appears in the Interfaces table with the expected IP address.
• The host remains reachable from an administrator workstation.
• The management interface loads after the change.
• DNS name resolution works if DNS settings were changed.
• VMs on networks that depend on the changed interface still communicate as expected.

Revert this change

If the new settings do not work and you still have web access, return to Networking, open the interface, and restore the previous IP address, subnet prefix, gateway, DNS servers, and DNS search domain. If the host is unreachable through the web console, use the local host console or the web terminal to inspect and restore the active connection. The following read-only commands confirm the current state before you change anything back:

15.5 Bridge Networking

Overview

A network bridge joins one or more host interfaces into a single layer-2 bridge. For virtualization, a bridge is used when virtual machines need to appear on the same external network as the SimpleVM host or other physical servers, rather than behind the NAT virtual network. A VM attached to a bridge can receive an address from the same upstream network as the host when the environment is configured for it. Treat bridge networking as a host task, because the bridge changes how the host’s physical interface is used; attaching a VM to the bridge is a VM-side task covered in Section 8.6, Configuring Virtual Networks and Section 10.2, Attaching VMs to Virtual Networks.

Before you begin

• Confirm the upstream switch port and VLAN are correct for the bridge.
• Confirm the bridge device name to use, such as bridge0 or another environment-specific name.
• Confirm whether the bridge should use DHCP or a static host IP address.
• Record the current IP settings of the physical interface before adding it to a bridge.
• Make sure you have console or out-of-band access, because bridge changes can temporarily disconnect the host.
• Do not create a bridge over Wi-Fi for production host networking.

Procedure

1. Open System > Networking.
2. In the Interfaces section, select Add bridge.
3. Enter the bridge device name.
4. Select the physical interface or interfaces that should become bridge ports.
5. Enable Spanning Tree Protocol only if your network design requires it.
6. Select Apply.
7. Open the new bridge interface and configure its IP settings on the bridge, using DHCP or manual addressing per your plan.
8. Confirm the physical port is listed as a bridge port and that the bridge interface carries the host IP address.

Verification

• The bridge appears in the Interfaces table.
• The expected physical interface appears as a port of the bridge.
• The bridge holds the host IP address if the host should be reachable through it.
• The management interface remains reachable from the network.
• A VM attached to the bridge communicates on the expected external network, if VM bridge testing is part of the change.

Revert this change

To revert a bridge, remove the physical interface from the bridge and restore its original IP settings, or delete the bridge. If the host loses access after the bridge is created, use the host console or out-of-band management to restore the previous connection.

• Open System > Networking.
• Select the bridge interface.
• Remove the physical interface from the bridge ports, or delete the bridge.
• Restore the original IP address, gateway, DNS, and search domain on the physical interface if needed.
• Verify the host is reachable at the expected management address.

15.6 DNS and Hostname Settings

Overview

DNS and hostname settings determine how the host resolves other systems and how administrators and services identify the host on the network. Correct DNS matters for software updates, support access, time synchronization, migration, clustering, and any workflow that uses fully qualified domain names instead of raw IP addresses.

DNS settings

DNS servers are configured on the connection that provides the host’s network access. With a static address, DNS servers and the search domain are usually entered manually; with DHCP, they may be supplied automatically by the DHCP server.

Procedure

1. Open System > Networking.
2. Select the interface or bridge that carries the host management address.
3. Open the IPv4 or IPv6 settings for that interface.
4. Add or update the DNS server addresses.
5. Add or update the DNS search domain if your environment uses one.
6. Select Apply.

Verification

• The interface shows the expected DNS server addresses and search domain.
• The host resolves internal names used by the environment.
• The host resolves update repositories or support endpoints if internet or repository access is required.

Confirm name resolution and the active hostname from the command line:

Hostname guidance

Use a stable hostname for each SimpleVM host. In production, avoid temporary or generic names: hostnames may be used in inventory, support records, monitoring, migration planning, and cluster documentation. Use a fully qualified domain name where your DNS design supports it.

15.7 Host Network Troubleshooting Basics

Overview

Work host network problems in layers: host reachability, interface status, IP addressing, DNS resolution, firewall behavior, bridge membership, and VM attachment. Separating the problem this way keeps you from changing the wrong setting while a production host or VM is affected.

Command-line checks

The web console is the primary workflow for routine host networking. The commands below help when the interface is unavailable or when support asks for diagnostic output. Run them from the web terminal or an SSH session; the terminal opens as svmadmin, so prefix privileged commands with sudo.