Unable to connect to the MKS: Failed to connect to server

kj0 · March 2014

So this one seems particularly strange, I have come across this before and can't remember how I fixed it.

In both Web Client and C# I am unable to connect to the VM on my second host through the gui console. I continue getting the error message: Umable to connect to the MKS: Failed to Connect to server 192.168.x.x:902

After researching for a while, the VMware KB was useless, I turned off all Windows firewalls, double checked the ports that were open on my Software firewall, made sure the VMware Workstation NICS were in the gateway exception list, I even turned off the firewall and attempted to connect to the console.

I am able to connect to the VMs on the first host, I have gone through the security profile double checking that everything is the same. This lab is completely new, I rebuilt it on the weekend and have just got to installing my second VM which just happens to end up being on the second host.

If any one has an idea, I would much appreciate it. This is doing my head in and I gotta keep labbing!

Thanks.

Asif Dasl · March 2014

I think this might be the error I get when running nested, I just reboot the host and it goes away. I need to install the "VMware Tools for Nested ESXi" though - that's if we are talking about the same error (it looks familiar though). Are you running with VMware tools installed?

kj0 · March 2014

Interesting. Out of the 3 or 4 times I've built this lab up with 5.5 I have only had this issue one other time. This does sound familiar though, and I'm pretty sure it was mentioned in William Lam's vForum presentation that I blogged about (Embarrassing not to remember that!)

I'll keep posted.

kj0 · March 2014

went all the way through, can see that VMwareTools are installed, however continuing to get the same issue. Shutting everything down again tonight and will attempt again tomorrow. It's almost tomorrow now!

SimonD. · March 2014

The times I have come across this it was down to DNS server configuration so I would have a look and see what the host is configured to use.

Essendon · March 2014

Yep, check DNS. Like Simon said, more often than not the cause of this error is DNS lookup failure. Is there a stale hosts file entry possibly?

jibbajabba · March 2014

Never had anything but DNS and firewall problems when receiving the error ..

tomtom1 · March 2014

Which version of ESXi are you running? There was a bug somewhere in time, I believe in the early 5 versions where the partition would get full. Deleting the /var/log/wtmp file would solve the issue. If this is not applicable, I'd check DNS and firewall connectivity. Since it's TCP, you could do a telnet to check connection issues.

Asif Dasl · March 2014

kj0 were you able to shutdown the host successfully? I think when I got the error I wasn't able to shutdown the host gracefully... I couldn't press Enter to wake up the DCUI.

edit - I've checked my DNS just to be on the safe side , but it's all good..

kj0 · March 2014

It isn't a stale record, The lab has only been built (Including DC) for 4 days. I will double check DNS, but DNS has been working. I had dropped the host from vCenter and added it back after restarting everything - hostname connected connected fine.

I also ran several dns Commands:

ipconfig /flushdns
ipconfig /registerdns
dnscmd /clearcache

All of which didn't fix the issue.

I'll have a bit more of a play with DNS tonight when I get home, I also got 5.5u1 so I will update that and go from there.

Thanks guys!

jibbajabba · March 2014

Thinking about it, DNS was mostly the problem in 4.x but in 5.x it was firewall related. It does work when you vmotion the VM to your other host?

As for firewall, don't forget, from the station you are connecting from you also need 902/3 access to the hosts the VM is hosted on. Have you tried connecting directly to the host using the C# client and opened the console?

Tried telnetting to host and vcenter using the hostnames and port 902?

Plus for arguments sake, added hosts and vcenter to your local hostfile ?

kj0 · March 2014

OH great, Host 1 thought it was a game and joined in! Now I can't get either.

Can't telnet either.. Hmm... I might finish building my SAN/Shared storage and work from there.

The strange thing that I am finding is that The two labs I had built on here, nothing has changed from those 2 to this one (Firewall and all - just DNS.)

jibbajabba · March 2014

You always think it is the same, yet sometimes its the subtle things

I just upgraded two hosts in my lab to 5.5u1 and neither comes up ... So clearly I missed some requirements somewhere myself ...

kj0 · March 2014

Well. I just upgraded to U1 on the hosts, about to log in. Still downloading the vCenter install. Maybe I should have just set up VUM :S

jibbajabba · March 2014

Wrong sequence mate ... If you don't have any other components (VCOPS / VCD etc.) start with vCenter before you do the hosts. Followed by VMware Tools on the VMs..

VMware KB: Update sequence for vSphere 5.5 and its compatible VMware products

kj0 · March 2014

This is why I'm doing the upgrade here at home first before work. Backup plan is to disconnect the hosts and then reconnect after upgrade.

kj0 · March 2014

Just an update. I've gone ahead and upgraded to 5.5u1 on my vCenter and on my hosts.

I am able to connect to all VMs under console by logging directly onto the hosts, however, if I log in through the vCenter server I continue to get the MKS 902 error.

I have gone through and refreshed the DNS, and performed checks all through it and everything is correct. i'm a little unsure now. But the main thing is that it's running and I can now at least build new VMs, so I can work around it, but ideally, one vSphere window would be nice.

jibbajabba · March 2014

You get the same when you RDP to the vCenter itself, open the client and check consoles from there, rather than remotely?

kj0 · March 2014

So, the host machine running VMware Workstation which has the ESXi Servers nested is what I'm using the Client on.

The next move is to install the client on the vCenter server itself and see if it does that same thing, that should eliminate where it is sitting.

kj0 · March 2014

That doesn't help. Connecting to vCenter using the client on the vCenter server works and i can see the full tree and connect to all consoles.

I can connect using the client to the the individual hosts. but not to vCenter itself.

SimonD. · March 2014

Check DNS on the host, vCenter server and workstation, honestly this was the same issue that I was having in my lab and I discovered that it was down to DNS (I want to think it was down to reverse DNS settings not having been set up correctly).

jibbajabba · March 2014

Hang on, so it works when you connect directly to the host and / or to the vcenter via RDP and then from there to the vcenter itself ?

Really sounds like DNS or a firewall issue. I hear you are using VMware Workstation as "host" - do you use NAT ?

kj0 · March 2014

Haven't check reverse DNS yet.

Not using RDP, just did that as a test. I'll send some more stuff through tonight.

kj0 · March 2014

So I went through and set up reverse DNS and it didn't make a difference, the Pointer records are set up. I restart all the server together in their correct order...

I've done a quick drawing of the levels of my set up. (Yes, quick, it's late here - Couldn't be bothered with a nice visio for tonight. Sorry)

If I connect directly to Host 1 or Host 2 (Using vSphere C#) I can connect to the console view of the VM running on that machine, If I connect to the vcenter the same way using vSphere C# and then open up either of the VMs console views I get the error.

I am connecting to vCenter and hosts using their Ips instead of Hostname (hasn't really made a difference)

If I remove the Hosts from vCenter, I can connect back to them using their Hostname (This would not work if DNS wasn't working) .

If I remote into the vCenter server and fire up vSphere C# inside, I can connect to vCenter but can not open Console View without getting the error.

Hope this makes more sense.

Thanks.

Asif Dasl · March 2014

If it were me, I would just have VMware workstation open with 4 tabs - 2 vSphere Hosts and DC/iSCSI Target and vCenter Server. There is no need to nest vCenter inside the host like you would on a production server. In my mind it's just unnecessary and more complex than it needs to be. The only one you have to place under the hosts is the VM.

My 0.02 cents

jibbajabba · March 2014

Oh you nested vcenter. I believe VMware Workstation allows promiscuous mode by default and cannot even be disabled, otherwise I would check there.

What virtual network are you using? Have you tried using direct confections rather than nat'ed ?

kj0 · March 2014

I"m using the same set up I have for the past year. I don't use NAT, I always use Bridged @ home and work. It makes it SO much easier!

I have Nested vCenter every other time, just this time seems different and getting the error, and I'm not sure why. I'll pull it out and make it "Physical" (a Virtual Physical in the design sense).

Unable to connect to the MKS: Failed to connect to server

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