Author Archives: Vyacheslav

“Lock the self-replacement of SIM” at Kyivstar

Usually, simple SIM cards of the Kyivstar mobile operator, bought in some kind of stall or store, can be replaced independently with a new SIM card, for example, you can buy another SIM card there and call the operator, say that the old card is lost, report the last few dialed and accepted numbers, then the operator will block the old SIM card and activate a new one but with the same number that was on the old one.

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How to remove an IP address from email blacklists

Once I had to remove from the blacklists IP addresses of different dedicated servers located in data centers, since some mail services did not receive emails from them, due to the fact that the previous tenant did not use the IP address honestly or had viruses, spammed, and the current one got locks.

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How to roll back the kernel version on Ubuntu

Sometimes after updating the kernel of the system, some important services start to work incorrectly and in order not to look for a problem on the combat server, and to do it for example later on the virtual one, you can boot the system from the previous version of the kernel.

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Why is the GRUB installed on a flash drive when installing Linux?

By default, the GRUB boot loader is installed on the first disk in the system, it is usually a hard disk, but on some servers with RAID controllers I noticed that when you turn on the server, select the USB flash drive in the Boot menu, of course, to boot from it, it becomes the first disk, then there is /dev/sda and at the end of the system installation the bootloader is installed on it.

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