blog.kaniski.eu I just wanna learn!

12Dec/180

Counters missing when machines accessed remotely

Not so long ago, we observed an issue with remotely accessing the PhysicalDisk counters on several machines, more specifically - there were none. 🙂

To be clear - if you opened up the Performance Monitor (perfmon.exe) on the affected machine, you can see all the counters, including the PhysicalDisk counters. But, if you opened up the Performance Monitor on a different machine and tried to access PhysicalDisk counters of the first machine over network, they aren't shown anymore... but others (like CPU and Memory) are still there and can be used!

Counters shown normally on local computer and in local Performance Monitor

The same counters not visible from remote machine's Performance Monitor

So... why? 🙂

At first, we thought that our monitoring software went berserk, but no - the PhysicalDisk counters on a remote machine were missing even we were using the built-in Performance Monitor tool (PhysicalDisk counters weren't shown).

Next - maybe it's something on the network? Of course, network is never the issue, but still... (wasn't an issue here as well, because other counters worked without any issues)

Next, we thought, it's related to the version of Windows accessing from, or the version at the destination - as we found out, too many different versions were impacted to hold that theory, so... no.

One thing we are not sure is if it's caused by some of the "not so recent security patches".

As we found the solution for our issue, what exactly caused it in the first place is not so important right now... Solution is simple - you actually need to run one command to re-register the system performance libraries with WMI (winmgmt /resyncperf) and then reboot the affected machine.

So, the commands you need are:

After that, we can access all the needed counters (PhysicalDisk) remotely again:

Counters shown normally from remote computer and in local Performance Monitor

Cheers!

P.S. Don't forget to reboot the affected machine! 🙂

21Oct/160

Show disk performance in Task Manager

One of the things that bothered me in the past was the fact that Task Manager showed all the required performance graphs, except the disk-related ones. Why is that, I don’t know. OK, you can see the disks through Resource Monitor console or PerfMon, but… I really like using Task Manager, with such nice colors and simple graphs, for a quick overall check.

So, when you’ve opened your Task Manager, you were shown something like this:

image

No disks. Too bad. Sad smile

But… fear not, my friend! There is a solution for this “glitch”. Even a simple one. Smile

All you need to do is run the following command in your administrative Command Prompt:

Like this:

image

And now, when you reopen your Task Manager, you will see following:

image

Cheers!

1Nov/140

Windows Firewall blocking pings

A short one this time… Smile

Have you ever had an issue with Windows Firewall blocking your pings on a network using Public profile, although the “File and Printer Sharing” exception is enabled for this profile?
(oh, yes, and don’t you dare to say that Windows Firewall should be disabled by default! Smile)

So, this is what I’m talking about:

image

As you see in the previous picture, the exception is enabled for both profiles (this PC is not domain-joined, but it would be the same with domain-joined PC on a network which is using the Public profile). When I try to ping it, I’m getting the standard “Request timed out.” message. Why is that? Is this a feature or bug?

Well, I’ve deliberately left-out two things:

  • if I try to ping my machine from the same subnet, the ping is passing through
  • if I try to ping my machine from the different subnet (routing is all set and working OK, in case you’re wondering), the ping is not passing through

The security feature that enables this kind of behavior is set in Windows Firewall by default – by default, Windows Firewall allows ping (and other traffic) only from the Local subnet, for all networks that use the Public profile. Of course, you may want to change this in certain scenarios (and you can… easily).

firewall_2

This is yet another thing that should be kept in mind during troubleshooting, right? (hope it helps) Smile

Have a great weekend!

25Oct/140

Resetting the switch – the harder way

Do you remember the (good) old Catalyst 500 series switches from Cisco?
I don’t think that they are something special nowadays (being the end-of-sale and end-of-life products), but if they are in working condition – fine, I can use them.

(if you are wondering what I’m talking about, here’s the picture)

WSCE500G12TCb

Anyhow, I’ve found one the other day (near mint condition), and wanted to make use of it in my lab. The only problem with it was that its password and IP and everything else was changed from factory defaults, without any note or document saying into what. Smile

So, the adventure begins…

Well, yes, you can say “But the switch works (at least the switching works). Why would any of this be a problem?”. The truth – I’ve had some spare time, and not having the complete access to my newfound piece of hardware was bugging me… Smile

The first thing I’ve tried was browsing the Cisco website for instructions on how to reset this type of switch. Note that this switch doesn’t have the ‘console’ interface, only web management. Soon I’ve found this article, explaining the whole process in great detail. Following the official instructions, I’ve come to the the part where my PC had to get the dynamic IP from the switch, but it was unable to get it (my PC actually got an APIPA address, but the other side wasn’t responding to queries on 169.254.0.1).

As per instructions, my switch could get either 169.254.0.1 or a 10.0.0.1 IP address, and I can easily set fixed IP on my PC and the problem will be solved. The thing that was bothering me is that I haven’t received the IP address from switch, as I should have and the question is why? I’ve discovered that I’m not the only one facing this issue – there’s even an article about this issue on Microsoft Answers. So, the problem seems to be in my DHCP BROADCAST flag on my PC (which is running Windows 10 Technical Preview, by the way). Long story short, the workaround provided didn’t help in my case.

And then I’ve taken another approach:

  • find out which address my switch has at the “setup time” (switch should be “talking” something during the setup, and probably a tool like WireShark or Microsoft Message Analyzer (great and free tool, by the way), can catch this “talk”)
  • set up my PC to the corresponding IP
  • try to access the configuration page
  • set up the router as I want to

So I’ve set up WireShark on my PC and started capturing the traffic... a lot of traffic… traffic that needs to be filtered by something. But what should the filter be?

Not so long ago, when my girlfriend was learning for her CCNA exam, she mentioned something called Cisco Discovery Protocol (CDP) and I’ve remembered that maybe this thing can help me now... so, I’ve entered the ‘cdp’ as a filter in WireShark and voilà – now I have something that actually seems useful!

image

From there, I’ve explored the CDP information in these filtered packets. In there, there is something called ‘Management Addresses’, which should be just the thing I’m looking for. And it is! I’ve seen that my switch actually has an IP of 169.254.180.146! It’s also safe to say that I never would have guessed it… would you? Smile

image

So, now I have the IP address of the management interface on my switch, and when I try to open it using my browser, I’ve got this:

image

Now comes the easy part – I’ve erased the system configuration, set the new one and this switch is finally ready to be used for whatever necessary.

image

And this is the end of this adventure. Switch is set to factory to defaults (and then configured as needed), I’ve been using CDP and WireShark to accomplish the task, and it was such fun! Can’t wait for the next adventure! Smile

Happy reading!

9Mar/104

Microsoft – povijest

welcometowindows Da li ste se ikada zapitali kako je Microsoft počeo raditi, kako su nastali Windowsi, što se točno događalo "tih davnih dana"?

Sigurno jeste, mnogi jesu... 🙂

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p>Slučajno sam naišao na ovaj članak pa bih ga želio podijeliti s vama. Ukoliko imate nekoliko minuta slobodnog vremena, mislim da se isplati "potrošiti" ih upravo na čitanje članka...