The solution to the error “Virtual machine could not be started because the hypervisor is not running”

I noticed once on one HP server, after installing Hyper-V, that virtual workstations are not being launched, giving the following error:

Hyper-V Manager
An error occurred while attempting to start the selected virtual machine(s).

Virtual machine could not be started because the hypervisor is not running.

As it turned out, the problem was in the Intel (R) Virualization Tech not activated in BIOS, after changing from “Disabled” to “Enabled” and start the system, the virtual workstations were successfully launched.

Backup configuration of TP-Link switches

I wrote a script for backup configuration of TP-Link switches.
The script runs on Linux where the TFTP server is running, it is connected via telnet to the switch and the configuration command is sent to the specified TFTP, when the telnet connection is closed, the file is moved to the desired directory, and the last command deletes files longer than 30 days, as more of them I do not need to store.
You can also make a copy of all the files in the cloud every month.
As you can see, before entering a password in the script, you can not pause.

#!/bin/bash
{
echo "PASSWORD";
echo "enable";
echo "PASSWORD";
echo "copy startup-config tftp ip-address 192.168.0.5 filename tplink";
sleep 2;
echo "exit";
sleep 1;
echo "exit";
} | telnet 192.168.0.110

mv /srv/tftp/tplink.cfg /backups/devices/tplink/`date +%Y-%m-%d`_tplink.cfg
find /backups/devices/tplink/ -type f -mtime +30 -exec rm {} \;

The reboot script of Wi-Fi routers TP-Link

Below is an example of the TP-Link router reboot script, I will test it on TL-WR720N 2.0 from Ubuntu Server.

#!/bin/sh
ROUTER_IP="192.168.24.174"
USERNAME="admin"
PASSWORD="admin"

# exit if router is down
ping -q -c 1 "$ROUTER_IP" > /dev/null || exit

curl --basic --user "$USERNAME:$PASSWORD" -A "Mozilla/4.73 [en] (X11; U; Linux 2.2.15 i686)" --refer "http://$ROUTER_IP" "$ROUTER_IP/userRpm/SysRebootRpm.htm?Reboot=reboot"

The contents of the script will be placed in a new file, for example, using the nano editor (“CTRL+X” to exit and “y” to save the changes):

nano file.sh

And make it executable:

chmod 777 file.sh

After this, we execute:

./file.sh

Similarly, you can perform other functions instead of rebooting.

How to close the link from indexing

To search engines Google, Yahoo!, Yandex and Bing, do not go through specific links and do not index them, and also to not pass on them PageRank, you need to add a special attribute to the link:

rel="nofollow"

For example:

<a href="example.com" rel="nofollow">Link text</a>

See also the information in this attribute in the Google Help Center – Attribute rel=”nofollow”
Information on Yandex – Using HTML tags

HP Pavilion dv7 Repair – White Screen

Noticed recently the appearance of a white screen at the time of work on the laptop HP Pavilion dv7.
When switching to an external monitor and back by a combination with the Fn key, the image was displayed normally, but after a while the problem appeared again.

The main reason for this phenomenon is likely to be a damaged or poor contact on the plume going to the display.
In my case, its disconnection/connection did not solve the problem, I had to order it on Aliexpress, it’s not expensive there.
Under the battery is written the full name of the laptop model for which you need to order a cable.

After replacing the loop, the problem was solved.

Configuring SSH checks in Zabbix

It took somehow some Linux servers to configure SSH checks to not install Zabbix-agent on them.
Zabbix-server itself is installed on Ubuntu Server.

Below in order I will describe how to configure SSH checks in Zabbix.

Authorization for SSH will be configured by key instead of password, for this we stop zabbix-agent and zabbix-server:

sudo service zabbix-agent stop
sudo service zabbix-server stop

Create a Zabbix user home directory (for storing ssh keys):

sudo usermod -m -d /home/zabbix zabbix
sudo chown zabbix:zabbix /home/zabbix
sudo chmod 700 /home/zabbix

Run back zabbix-agent and zabbix-server:

sudo service zabbix-agent start
sudo service zabbix-server start

Open the configuration file /etc/zabbix/zabbix_server.conf (in the nano editor, press Ctrl+O and Enter means save, Ctrl+X to exit):

sudo nano /etc/zabbix/zabbix_server.conf

Uncomment the string SSHKeyLocation and specify the path to the directory with the keys:

SSHKeyLocation=/home/zabbix/.ssh

Restart zabbix-server:

sudo service zabbix-server restart

Generate the ssh key:

sudo -u zabbix ssh-keygen -t rsa

Press Enter if the path is /home/zabbix/.ssh/id_rsa
On the offer to encrypt the key file, press Enter to not encrypt it or enter twice any password (it will encrypt the key file and you will have to specify it when connecting it)

Copy the generated key to the server we will be watching:

sudo -u zabbix ssh-copy-id -i /home/zabbix/.ssh/id_rsa.pub -p 22 root@192.168.0.55

If an error occurs while copying the key, you can manually copy the line from id_rsa.pub to the remote server in the authorized_keys file.

And we will try to connect to the remote server without entering the password with the command:

sudo -u zabbix ssh -p 22 root@192.168.0.55

Now in Zabbix we add the data element to the template or host:
Name: any
Type: SSH agent
Key: ssh.run[description,ip,port,encoding] (eg ssh.run[cpu,192.168.0.55,22,utf8]
Authentication method: Public key
User name (on remote host): root
Public key file: id_rsa.pub
Private key file: id_rsa
Phrase key password: leave blank if you did not encrypt the key with a password
Executed script: command running on a remote server, examples below

Below is an example of commands for Linux that you can execute and get various information.
CPU load for 1min / 5min / 15min:

cat /proc/loadavg |cut -d " " -f1
cat /proc/loadavg |cut -d " " -f2
cat /proc/loadavg |cut -d " " -f3

Number of currently running processes of the specified program:

pgrep apache2|wc -l
pgrep -c sshd

Free space at the mount point “/” (in megabytes):

df -m|grep "/$"|awk '{print $4}'

Occupied space at the mount point “/” (in percent):

df|grep "/$"|awk '{print $5}'|tr -d "%"

Received byte on the network interface eth0:

cat /proc/net/dev|grep eth0|awk '{print $2}'

Bytes sent to the network interface eth0:

cat /proc/net/dev|grep eth0|awk '{print $10}'

Amount of free RAM:

free |grep "Memory:"|awk '{print $4}'
free |grep "Mem:"|awk '{print $4}'

See also:
Connect to SSH using the keys

Configuring a VPN Server in Windows Server

On the test I give an example of setting up a VPN server in Windows Server 2008 R2.

First of all, install the role:

1) Open the server manager and click on the link “Add role“.

2) Select the Network Policy and Access Services role and click “Next“.

3) Select “Remote Access” and click “Next“.

4) Click “Install” and after the installation is complete, click the “Close” button.

Now go to the setup:

1) Open the server manager, open the “Roles” branch, select the Network Policy and Access Services role, right-click on “Routing and Remote Access“, select “Configure and enable routing and remote access“.

2) In the first window click “Next“, in the next we’ll select “Custom configuration“, click the “Next” button, tick three items: Network Address Translation (NAT) and Local Area Networking (LAN routing), click Next and “Done“.
In the window that appears, click “Launch service“.

3) We’ll add an address pool for clients by opening the “Server Manager” – “Roles” – “Network Policy and Access Services“, right-click on “Routing and Remote Access” and select “Properties“.
In the “IPv4 tab, select” Static address pool “and add any range after clicking the “Add” button.
In order to be able to connect to a VPN server, for example, from the iPhone (via L2TP), in the “Security” tab, tick “Allow custom IPSec policies for L2TP connection” and specify the key .

4) Now configure permissions for users. Go to “Server Manager – Configuration – Local Users and Groups – Users“:
Open “Properties” of the desired user and on the Dial-in tab, where “Network Access permission” select “Allow access“.

5) Add NAT rules, the necessary routes and restart the service by right-clicking on “Routing and Remote Access” – “All Tasks” – “Restart “.

For the VPN to work, ports are used and should be opened:
TCP 1723 (for PPTP)
TCP 1701 and UDP 500 (for L2TP)
TCP 443 (for SSTP)

Done.

Connection logs can be seen in the C:\Windows\System32\LogFiles directory

Solution of the error “Invalid command ‘AuthGroupFile'”

I noticed once the following error:

AH00526: Syntax error on line 26 of /etc/apache2/sites-enabled/000-default.conf:
Invalid command ‘AuthGroupFile’, perhaps misspelled or defined by a module not included in the server configuration
Action ‘configtest’ failed.
The Apache error log may have more information.

It is solved simply by activating the module:

sudo a2enmod authz_groupfile

Restart apache2 to apply the changes:

sudo service apache2 restart

Done.