Update to Promiscous Mode on vSphere 4

A few months back I wrote about Enabling Promiscuous Mode on vSphere 4. Well, I have learned some more since then. There isn't much information out there about recording a VoIP stream in a virtual machine environment. I hope to change that today.

First thing is first. If you are using VLANS on your physical network set your Virtual Machine Port Group to be a trunk. Also set the port on the physical switch to be a trunk instead of an access port.

Second thing, if you are using the E1000 NIC driver in your guest OS, turn off VLAN support. The screen shot is from Windows 2008 R2 64-bit, but it is similar in every other Windows OS.







Performance Best Practices for vSphere 4

Enabling Promiscuous Mode on vSphere 4

We are in desperate need of a testing server. The testing server needs to be able to listen to the network, through port mirroring, to record VoIP calls. In the physical world this is no problem, but we don't have the budget for another physical box, especially for something as non-critical as testing a program upgrade (even though the program it self is very critical to our business).

A year ago the software vendor said that they don't support virtual environments and their product doesn't work in a virtual environment. During discussions this year however they told the truth that they simply don't know if it will work, and thus "don't support" it. I am calling it lazy. It doesn't take much these days to get a VM host going and configured for testing things out.

Well we have done the leg work for them. I have confirmed that vSphere does allow for promiscuous mode, even from the physical network. To be honest I was a little shocked to see this worked.

Here are the steps to enable promiscuous mode on your vSphere host and the guest VM.

1. Enable promiscuous mode on the virtual adapter.
   
2. Enable promiscuous mode on the vSwitch.
3. Enable promiscuous mode for the guest.
4. Enable port mirroring on the physical switch (not covered here).
5. Test capturing network data.

Now that we have the general synopsis of the procedure we can begin.

We enable promiscuous mode on the virtual adapter by logging into the vSphere Client, going to the VM Host, clicking on the "Configuration" tab, then on "Networking" in the "Hardware" section on the left. Now click on "Properties..." for the Virtual Switch.


Now enabling promiscuous mode on the vSwitch is pretty simple. Click on the "vSwitch" on the "Ports" tab, as shown below and then click on the "Edit..." button.



Now that we are editing the vSwitch properties click on the "Security" tab. Change the option for Promiscuous mode to "Accept" if it isn't already and hit "OK".


To enable promiscuous mode for the guest we need to break down to the command line. I used putty to SSH into my vSphere host, which I had previously setup. Now you need to edit the .vmx file of the guest that will be listening to the network.

# vi /vmfs/volumes/datastore1/testServer/testServer.vmx

I did a search for ethernet, so the promiscuous mode configuration would be with the rest of the ethernet config. Add the following line to the configuration file:

ethernet0.noPromisc = "FALSE"



And save when you are done. I rebooted my testServer just as a precaution, but I'm not certain it is required.

At this point everything is configured on the VM side of things. Make sure you have port mirroring enabled on your physical switch and give it a test. In my environment I commonly use Wireshark. I did my testing by pinging a server on a mirrored port.

How to Reset the Password(s) on a Linksys SRW248G4 Switch

1. Connect to the Serial port on the back of the switch with a serial cable. (Putty on Windows works well)
2. The defaults for connecting to the serial port are 38400 baud, 8 data bits, no parity, 1 stop bit, no flow control.
3. Confirm that you have an active serial connection by pressing enter a couple of times. You should receive a login screen
4. Once you have successfully connected to the serial port restart the switch by unplugging the power. (Either from back or from the power strip, my preferred method is the back)
5. The switch will start its POST process.
6. Look for the line “Autoboot in 2 seconds - press RETURN or Esc. to abort and enter prom.” (Please note: Do not hold down Esc. or Enter. Only press it once.)
7. You will know that you interrupted the boot sequence when you are prompted with a startup menu. Select option 3 “Password Recovery Procedure”.
8. The screen will display “The current password will be ignored!”. Press Enter to reboot the switch.
9. Once the switch has restarted login with the default admin user and no password. This will work on either the terminal or the web interface. Proceed to create / modify users and passwords. This does not reset the rest of the configuration, just user accounts.
10. Once you have your new credentials reboot the switch again. Document the credentials.
11. Verify that your new credentials work by logging into either the web interface for the command line interface.
12. Disconnect the cable and store it safely.

This is the second time I have required these instructions, so I am posting them here for safe keeping. The last time I did this I removed the default account and setup individual accounts, and then promptly forgot everything about it. This is why documentation is so critical.

3Com Switch find Uptime

We had another incident with our VoIP phones restarting on Friday. As part of my troubleshooting efforts I needed to be 100% certain that the POE switch providing power to our phone didn't reboot.

To start there is no display uptime command in the CLI. But if you run the display version command part of the output is "Switch 4500 PWR 50-Port uptime is 6 weeks, 5 days, 2 hours, 25 minutes". This is exactly what I was looking for!

It should also be noted that the web interface for the switch shows the uptime on the device summary page.

Upgrading the Firmware on a 3com 4500 switch

Again, this is mostly for my own notes, but someone else may find it useful. Last year we purchased a 3c0m POE switch for our new VoIP phone system. This year I needed to update the firmware on it, but with only 8MB of flash drive I ran into a few problems.

First off, BACK UP EVERYTHING!

I used the TFTP method to transfer files to and from the switch. I used Solarwinds TFTP Server on my PC.

File name Prefix / Suffix

s3n / .app = 4500 application software.

s30 / .btm = 4500 boot ROM software

s3p / .web = 4500 web file (HTTP management interface)

3comOScfg.def / .def = 4500 config file

So first things first backing up via TFTP:

<4500>tftp [IP OF TFTP SERVER] put flash:/s3004_01.btm

<4500>tftp [IP OF TFTP SERVER] put flash:/s3p04_03.web

<4500>tftp [IP OF TFTP SERVER] put flash:/s3n03_03_02s56p05.app

<4500>tftp [IP OF TFTP SERVER] put flash:/3comOScfg.def

Please change these files as you see fit. Do a dir on the root directory to get the listing for your particular switch.

Now that we have that backed up we need to clean up the flash:/ drive to make room for the updates.

<4500>delete s3004_01.btm

<4500>delete s3p04_03.web

<4500>detete s3n03_03_02s56p05.app

Now we also have to empty the recycle-bin. This is where I got stuck as I didn't know a CLI could have a recycle-bin, or have never seen it done before.

<4500>reset recycle-bin

See as we now have the free space we need to get the new files we can pull them down from the TFTP server.

<4500>tftp [IP OF TFTP SERVER] get s3p02_01.web

<4500>tftp [IP OF TFTP SERVER] get s3o01_01.btm

<4500>tftp [IP OF TFTP SERVER] get s3n03_02_00s56.app

Again, you will need to use the files that are the current firmware update.

One of the last steps is to tell the switch what files to use on next boot.

<4500>boot boot-loader flash:/s3n03_02_00s56.app

<4500>boot bootrom flash:/s3o02_01.btm

Finally we will save the configuration and reboot the switch.

<4500>save

<4500>reboot

Thats it! After the switch reboots you will be running the newest software, except for the .web file. For some reason this is left out of all of the documentation that comes with the update. I didn't write down the commands I used to get it to update, and I honestly don't think they worked.