Archive for December, 2013

VMware ESXi / VMware Player & KVM Preinstalled machines

VMware ESXi / VMware Player & KVM Preinstalled machines.       Quick link to browse download directory: https://www.7layer.org/downloads 

I”ve started making preinstalled ready to use virtual machines for everybody, no charges for this.
Machines will be categorized and sorted shortly. Machines can run on Windows, Linux, Apple Server and Client.
Image formats: OVF http://en.wikipedia.org/wiki/Open_Virtualization_Format & KVM http://en.wikipedia.org/wiki/Kernel-based_Virtual_Machine based.

If you have not used VMware before then follow this link: https://my.vmware.com/web/vmware/free#desktop_end_user_computing/vmware_player/6_0  and download the Player(for client) or the ESXi(for server) whichever you want to use. The Player can be used on any running Windows/Linux/Apple client and the ESXi server can be used only as server. Both of them free, no need to pay any licence for them and no time limit restriction either.
Although on ESXi server you must upload the free ESXi license number which you got when you downloaded it in 60 day time.

You can import these machines and start using it straight away.

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Debian based Named DNS master-slave server.

Master server:
 Debian-master-dns readme
Slave server: Debian-slave-dns readme
References: http://www.bind9.net/arm97.pdfhttp://www.howtoforge.com/debian_bind9_master_slave_system

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pfSense OVF template image with Squid proxy server.
pfSense server: pfSense readme
References: https://doc.pfsense.org/index.php/PfSense_2_on_VMware_ESXi_5#Booting_your_VM_from_CD.2FDVD

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CentOS 6.5 based server with Squid proxy and Webmin server.

CentOS 6.5: 64bit 32bit readme
References: http://www.centos.org/docs/5/

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Linux/Windows Troubleshooting part 2

Network troubleshooting part 2:

The next article is about some basic DNS troubleshooting.
First we will do it on Linux with dig command, then we will check out nslookup on Windows too.

dig any 7layer.org @8.8.8.8

This command will check 7layer.org domain at google’s DNS server(@8.8.8.8) and will ask for all available records (any) on this domain.
I have highlighted every important parts of this command. All in all 7 records been found as you can see on this picture above:

dns-1

 

You can change the server easily with the @ part. You can put your own DNS server if you want to check your updated local DNS server.
The fully DNS zone propagation(update) theoretically takes 2 days, but usually enough few hours to get updated nearly everywhere.
If you completely lose the @server-IP-address then dig will use the current DNS server address from /etc/resolv.conf.
For example:

dig any 7layer.org

To check only the MX records for the domain change the any to mx like this:

dig mx 7layer.org

dns-5

The next one is how to check the reverse record for the domain.

dig -x 78.46.184.202

As you can see in the answer section the command found the reverse record for the domain which is mail.7layer.org.

dns-2

So let’s take a look at this with Windows nslookup:

nslookup

server 8.8.8.8

set type=any

7layer.org

dns-3

 

You can see that in the answer parts all the nameserver addresses and A records are there, also both MX records have been presented.
To check only MX records then you could easily change the type to mx, like this:

set type=mx

You will get only the MX records result from the server:

dns-4

 

Windows Update troubles:

I was just updating few servers at my workplace remotely at the datacenter and 1 of them didn’t reboot properly.

So the issue was this:

– Server updated with new service packs.
– Reboot has been processed and started via RDP(remote desktop).
– The RDP can’t be reachable anymore, because that service has been shut down already and connections has been shut down.
– Server still pingable.
– No any other way to reach the server anymore. (IPMI/KVM/DRAC)

Solutions: 

– Go to datacenter and restart the server manually. On Saturday is not a good fun, let’s be honest
– Phone up the datacenter to ask for remote hand… Takes ages to explain everything, server number, rack location etc…
– Download PsTools from here: http://technet.microsoft.com/en-gb/sysinternals/bb896649.aspx and kill the winlogon process which stuck on the server.

Extract PsTools and first try this command:

psexec \\REMOTE_SERVER_NAME shutdown /r /t 0

This will try to execute shutdown command on the remote box and restart the server. The /r means reboot the /t switch is the time which is zero.
If this wont help for some reason then you could try to use the pskill.exe command.

pskill [-t] [\\computer [-u username [-p password]]] <process ID | name>

pskill \\10.0.0.10 -u mydomain\Administrator -p mylovelypassword Winlogon

This should work and you wont need to go to datacenter neither to phone them up and asking for the reboot.
You can monitor the server with ping command and you will see when the server really reboots, because you will lose ping from it.

This one saved me so many times on my weekends, when I usually make Windows updates. ( Just like right now:) )
Weekdays you can’t really do Windows updates on corporate servers, because they are heavily used by users, so reboot is not a good idea that time.

Next issue will be posted shortly…

 
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