WAN Emulation using WANEm


Let's say that we have to test some application, that can be a web application, a TCP/IP application or any other kind of connection, in an environment that simulates the WAN.

First of all we have to design the network environment.

Most times, I use a Hyper-V environment to do setup the machines and networks needed for the test.

Lets say that we've already setup a server and a client as virtual machines with names SERVERVM and CLIENTVM respectively. Each has one virtual network adapter.

Now we need to create two new virtual networks, let's name them SERVERNET and CLIENTNET. We connect the client's adapter to the CLIENTNET and server's adapter to SERVERNET.

The next thing we have to do is create the WAN emulation virtual machine. I prefer to user the WANEm emulator. So grab a copy of the ISO and create a new VM. If you are using Hyper-V, remove the Virtual Network Adapter from the VM and add two new Legacy Network Adapters. Connect the adapters to the networks we created earlier. In order not to get confused with the networks and the adapters, write down the MAC addresses from the hypervisor.

When the VM finishes booting, you will have to configure the IP addresses for the interfaces. I always use static addresses here. Usually the eth0 adapter is the first adapter in the list of Hyper-V. You can check it though with ifconfig and the MAC addresses you got earlier. An other way to check is to connect only one network adapter and ping the emulator from another machine.

After you have setup the VM with the IP addresses, you have to configure the routing on the SERVERVM and CLIENTVM. Depending on your network set you may not have to do this. I on the other hand, prefer to use different subnets for the two networks. In that case, you may use the emulator IPs as gateways on the other vms or just add routes on them.

If you can ping the emulator from both vms and one vm from the other, you're all set. The next thing to do is configure the emulation rules.

You can configure these by opening the website of the emulator which is http://<emulatorip>/WANEm. Notice that the "WANEm" part is case sensitive. You may then apply emulation rules on each adapter (You have these written down, right?).

I use the above frequently to do POCs and troubleshoot may things and one problem that comes up is the connection to the internet. In order to connect the networks to the internet we have to connect the emulator to a network with internet access and setup NAT for the other networks.

To do this I add a new Legacy Virtual Network Adapter and connect it to the local ethernet. I assign IP addresses just like we did before and then setup routing on the emulator just like in any other linux.

In order to setup NAT you may use the following commands:
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
iptables -A FORWARD -i eth1 -j ACCEPT

where eth0 is the adapter that is connected to the network with internet access and eth1 and eth2 are the adapters connected to the other networks.

A very useful article on this is this.

One last thing, you have to use the emulator as default gateway on the machines that are connected to the private networks for NAT to work. If you want to access these networks from other machines that do not have the emulator as default gateway, just add routes on them.

Popular posts from this blog

Domain Controller Machine Password Reset

Image
On my lab environment, I've configured two Active Directory sites since most enterprises have offices in more that one places. My lab however is not running 24/7 and the domain controllers in the second site are rarely turned on in order to save resources. This leads to issues with the Active Directory replication such as the "The target principal name is incorrect" error when I execute:  repadmin /syncall /AdeP. To remedy the issue, we have to reset the machine password of the domain controller that has been offline. First off, we are going to stop and disable the Kerberos Key Distribution Center (kdc) service on the problematic domain controller, in our case DC4. There may be some tickets in the cache so we should also clear them using klist purge Now it's time to change the machine password of the domain controller using the command netdom resetpwd /s:dc3 /ud:lab\administrator /pd:* Replace the "lab\administrator" with an account on your...
Keep reading

Managing Active Directory User Certificates using PowerShell

I first came across user certificates when I was working with email certificates a few years ago and I have to admit that I had trouble updating the certificates on the objects! Most organizations have a Microsoft Active Directory Certification Authority that issues the certificates used internally. When a certificate is issued to a user, the Microsoft Certificate Service saves the public key in Active Directory. The userCertificate attribute is a multi-valued attribute that contains the DER-encoded X509v3 certificates issued to the user. Although we rarely need to pay attention to this attribute, there are cases where we have to update it. To make things easier, I've written PowerShell functions to Get, Remove, Import and Export the certificates on that field. To get the list of certificates for an object, use the Get-ActiveDirectoryObjectCertificate function: PS C:\> Get-ActiveDirectoryObjectCertificate -UserPrincipalName cpolydorou@lab.local DistinguishedName  ...
Keep reading

Configuring a Certificate on Exchange Receive Connector

Today's article is about configuring Exchange receive connectors with specific certificates. Out of the box, Exchange uses self signed certificates to provide TLS secured mail flow. This will definitely be an issue if you expose the SMTP protocol to client computers since they won't trust the certificate. In this article we are going to configure a certificate that was issued by a third part authority to the Client Frontend receive connector. We'll start with getting the thumbprint of the certificate using the Get-ExchangeCertificate cmdlet: [PS] C:\> Get-ExchangeCertificate Thumbprint                               Subject ----------                               ------- 241B864DC82C664FECBA18B8D54987AAFB65B4C2 CN=*.lab.com, ... D4D210886B34E690191A1F008C78FDD0E7325DD4 CN=Exchange2013A 960171662EB26116...
Keep reading