IPv4 Static Router

# IPv4 Static Router This activity creates statically configured routing in __`r1`__ and __`r2`__. These routers are placed in an inter-network hierarchy and traffic is observed as it is routed between the networks. ## Deliverable ![image](https://hackmd.io/_uploads/r14FoOJjT.png) ## Setup Three distinct IP networks need to exist by the end of the activity. - __Host-Only Network #2__. Network Address: 10.20.30.0/24 - __net1__ (`net1a` & `net1b` joined by the bridge in __r1__). Network Address: 172.18.0.0/24 - __net2__. Network Address: 172.28.0.0/24 The following VMs will need to exist: - __instr_rtr__: imported as an appliance in the previous milestone - __r1__: created in the previous milestone - __r2__: created in the previous milestone - __web__: created in the previous milestone - __ws1__: created in the previous milestone - __ws2__: newly created VM that is a linked clone of __centos_8_base__ - __ws3__: (optional) newly created VM that is a linked clone of **centos_8_base** Attached to __Host-Only Network #2__ are the following VM's: - __instr_rtr__ - __r1__ - __r2__ Attached to the __net1a__ network are the following VM's: - __r1__ - __web__ Attached to the **net1b** network are the following VM's: - __r1__ - __ws1__ :::info :bulb: Note that __net1a__ and __net1b__, though initially distinct networks, are now part of the same broadcast domain (i.e. same LAN) thanks to the bridge configured in __r1__. ::: Attached to the __net2__ network are the following VM's: - __r2__: An additional Paravirtualized Network Adapter (virtio-net) will need to be added to this device. Ensure it is connected to an internal network named __net2__ - :new: __ws2__: (linked clone based on the __centos_8_base__ image; should have a single network adapter attached to __net2__ network) - :new: __ws3__ (Optional) (linked clone based on the __centos_8_base__ image; should have a single network adapter attached to __net2__ network ## Router Configuration :::info :bulb: Configuration steps: 1. IP configuration of router interfaces: `enp0s3` and `br0` for __r1__, `enp0s3` and `enp0s8` for __r2__ 1. Enable IP forwarding 1. Configure routes ::: You will need to use the __NetworkManager__ through the `nmcli/nmtui` tools to create permanent configuration in the two routers and associated hosts. It is perhaps easier to complete the following steps using the `nmtui` tool, but if you prefer working on the command line, a command reference for `nmcli` can be found under command hints heading at the bottom of this section: ### Configuring __r1__ 1. Start by detaching the `enp0s3` interface from the bridge. The quickest way to do this would be to first delete the `enp0s3` configuration. The following command will do it: ``` sudo nmcli con delete enp0s3 ``` At this point, the bridge will be left in control of the remaining two interfaces, i.e. `enp0s8` and `enp0s9`. Then run the following command to create a new configuration for the `enp0s3` interface: ``` sudo nmcli con add type ethernet con-name enp0s3 ifname enp0s3 ``` Now you are ready to proceed with the next steps. 2. Using the nmtui or nmcli tools, edit the `enp0s3` IP configuration as follows: - Switch from __Automatic__ to __Manual__ configuration - In the IP address field, enter: __10.20.30.100/24__ - In the Gateway field, enter: __10.20.30.254__ - Select the __Edit__ button next to the __Routing tab__, and enter a destination and next-hop values for the __net2__ subnet (you should understand what that means at this point) - Save your changes and proceed to the next step 3. Edit the bridge IP configuration as follows: - Switch from __Automatic__ to __Manual__ configuration - In the IP address field, enter: __172.18.0.1/24__ - Save your changes and proceed to the next step 4. Re-activate both the `enp0s3` and the bridge interfaces 5. Enable IP forwarding (__see the note at the end of this section__) ### Configuring __r2__ 1. Before going any further, ensure you __have enabled a second adapter__ and attached it to an internal network named __net2__ as described in the setup notes above 2. Using the `nmtui` or `nmcli` tools, edit the `enp0s3` IP configuration as follows: - Switch from __Automatic__ to __Manual__ configuration - In the IP address field, enter: __10.20.30.200/24__ - In the Gateway field, enter: __10.20.30.254__ - Select the __Edit__ button next to the __Routing tab__, and enter a destination and next-hop values for the __net1__ subnet (you should understand what that means at this point) - Save your changes and proceed to the next step 3. Edit the `enp0s8` IP configuration as follows: - Switch from __Automatic__ to __Manual__ configuration - In the IP address field, enter: __172.28.0.1/24__ - Save your changes and proceed to the next step 4. Re-activate both the `enp0s3` and the `enp0s8` interfaces 5. Enable IP forwarding (**see the note at the end of this section**) :::info ### Enabling IP Forwarding IP forwarding is the mechanism by which a host takes packets coming through one interface and forward them out through another interface. This is not enabled by default. To enable it, proceed as follows: - Using a text editor such as __Vim__ or __nano__, open the following file: /etc/sysctl.conf and add the following line at the bottom of it (this requires root privileges, i.e. __sudo__): ``` net.ipv4.ip_forward = 1 ``` Run the following command to activate the changes: ``` sudo sysctl --system ``` ::: :::info :bulb: <h3 name="nmcli-command-reference">nmcli command reference</h3> Delete a connection: ``` sudo nmcli con delete [connection_name] ``` Create connection and configure IP: ``` sudo nmcli con add type ethernet con-name [connection_name] ifname [interface_name] ipv4.addresses [IP]/[cidr] ipv4.method manual ipv4.gateway [GATEWAY_IP] +ipv4.routes "[network_id] [gateway]" ``` The previous command can be broken down into multiple steps using the nmcli con modify command: Configure default route: ``` sudo nmcli con modify [connection_name] ipv4.gateway [GATEWAY_IP] ``` Configure routes: ``` sudo nmcli con modify [connection_name] +ipv4.routes "[network_id] [gateway]" ``` Save changes: ``` sudo nmcli con reload ``` ::: ## Host Configuration IP configuration for __web__, __ws1__, __ws2__, and optionally __ws3__ is done in a similar fashion. So the steps provided below apply to all of them, but pay attention to the different values for each: 1. Before going any further, ensure __ws2__ (and optionally __ws3__) exist and are attached to the __net2__ network as described in the setup note above. 2. Using the `nmtui/nmcli` tools, edit the `enp0s3` IP configuration as follows: - Switch from __Automatic__ to __Manual__ configuration - In the IP Address field, enter: - __web__: 172.18.0.10/24 - __ws1__: 172.18.0.20/24 - __ws2__: 172.28.0.10/24 - __ws3__: 172.28.0.20/24 (this is optional) - In the Gateway field, enter: - __web__ and __ws1__: 172.18.0.1 - __ws2__ and __ws3__: 172.28.0.1 - Save the changes and re-activate the interface. ## Troubleshooting - Verify that links are active: `ip link show` - Verify IP address on interfaces: `ip addr` - Verify routing configuration: `ip route show` (this is also how you find the default gateway for a host) - Test connectivity and routing (you may also use `ping`): - In **web**: `sudo traceroute -I 172.18.0.1` - In **web**: `sudo traceroute -I 10.20.30.100` - In **web**: `sudo traceroute -I 10.20.30.200` - In **web**: `sudo traceroute -I 172.28.0.1` - In **web**: `sudo traceroute -I 172.28.0.10` - In **ws2**: do the reverse of the previous traces After verifying that everything works correctly, submit your report to the milestone's dropbox folder.