Cron — task scheduler in UNIX-like operating systems, used for periodic execution of tasks at a certain time.
Continue reading “Using and configuring CRON”Author Archives: Vyacheslav
Installing and Using dhcpdump
dhcpdump – sniffer utility for analyzing DHCP packets.
Continue reading “Installing and Using dhcpdump”Change port in SSH, HTTP, etc. checks. in Zabbix
Suppose that SSH is working on a non-standard port, in Zabbix, the “Template App SSH Service” template checks it on a standard port and will therefore send out the message “SSH service is down on …”.
To specify which port to check for SSH, we will make a complete cloning of the “Template App SSH Service” template so that it does not change it and in the new cloned template we already change the key in the data element:
net.tcp.service[ssh]
to (where 500 is the SSH port number):
net.tcp.service[ssh,,500]
And we’ll specify this new template instead of the standard one, then SSH will be scanned at the specified port.
Templates are configured in the “Settings” -> “Templates” -> “Templates” group.
Similarly, the port for other services changes.
From the command line, you can check it with the following commands:
zabbix_get -s127.0.0.1 -k'net.tcp.service[ssh]' zabbix_get -s127.0.0.1 -k'net.tcp.service[ssh,,500]'
If Zabbix-agent is installed on the node, then in the field the key is better to specify:
proc.num[sshd]
Monitoring DNS from Zabbix
To monitor the DNS service itself on the port, you can use the following key in the data items (where SERVER is the IP address or DNS server domain):
net.tcp.dns[SERVER]
In order not to create a template from scratch, you can clone eg the standard “Template App SSH Service” by changing the name in it and specifying a new key, the trigger will change automatically. And also in the “Type” we select “Zabbix agent” instead of a simple check.
The next command can be checked from the Linux command line:
zabbix_get -s127.0.0.1 -k'net.tcp.dns[SERVER]'
Naturally, if the answer is 1, the DNS service is started, 0 is not.
If Zabbix-agent is installed on the node, then in the field the key is better to specify:
proc.num[nemed]
See also my article:
Monitoring Bind9 in Zabbix
IPTables rules for TFTP
To open the TFTP port in IPTables, we will run the rule:
Continue reading “IPTables rules for TFTP”Where is auto startup folder in Windows 10?
It took today on Windows 10 to add a shortcut to the program in startup, started looking in the menu, but there is no it.
Therefore, I will describe a couple of options where to find this folder “Startup”.
Option 1) The folder for each user is located separately, for example, in my case (user admin), the path to it is:
C:\Users\admin\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup
admin can be replaced with the correct user name and paste this path into the address bar of the explorer. The AppData folder is hidden, so if you open folders one by one, you will have to type it manually in the address bar of the explorer.
Option 2) Open the line “Run” in the menu or by pressing Win+R and type:
shell:startup
In this case, the “Startup” folder of the current user will be displayed.
To open the shared folder “Startup” which is valid for all users, type:
shell:common startup
To remove something from the startup, you do not have to delete the shortcut from the Startup folder, you can open the Task Manager with the shortcut Ctrl+Shift+Esc and the “Startup” right-click the desired object and select “Disable“. In this tab, you can also disable objects that are added to the startup registry.
Done.
The solution to the error “ImportError: No module named ldap”
Installed iRedMail on Ubuntu Server in February 2016 and noticed an error when trying to send a message via Roundcube:
SMTP error (451): Unable to add recipient “Email” (4.3.5 Server configuration problem)
I checked if iredapd is running:
telnet localhost 7777
It turned out that it was not running because the response from telnet was displayed:
Unable to connect to remote host: Connection refused
Tried to run:
sudo /etc/init.d/iredapd start
To which he received the answer:
ImportError: No module named ldap
I installed the module with the command:
sudo apt-get install python-ldap
Execute the commands:
sudo -i cd /opt/iredapd/ find . -name '*pyc' | xargs rm -f {}
Now restart the service:
sudo service iredapd restart
Done, there is no error.
Firmware Update BlackVue DR650GW-2CH
I will describe the procedure for updating the firmware BlackVue DR650GW-2CH:
Continue reading “Firmware Update BlackVue DR650GW-2CH”Starting a TFTP server in Windows
One of the options for running the tftp server on Windows is to download and run the application from the link http://tftpd32.jounin.net/tftpd32_download.html
Continue reading “Starting a TFTP server in Windows”Turning test mode on and off in Windows 7
Sometimes I had to put unsigned drivers to flash different junk, so I included a test mode in which the installation of unsigned drivers is allowed. If the test mode is disabled, the drivers will stop working again.
You can enable the test mode in Windows 7 from the command line (cmd) or from the “Run” line which is opened by the Win+R key combination.
In any of the lines, you need to run the following command to enable the test mode:
bcdedit.exe -set TESTSIGNING ON
To turn off:
bcdedit.exe -set TESTSIGNING OFF
After each command, you must restart the computer.
When the test mode is enabled, the “Test mode” and the version of the Windows assembly are displayed on the desktop in the lower right corner.