Developers Club geek daily blog

Manual editing of uboot-elf for the sake of DHCP and SSH

1 year, 9 months ago
Somehow time the piece of iron of AEWIN SCB-3240 which should nevermore have lodged in a server rack with the purpose forever fell of me into hands to touch it. It was going to use it not directly, and for the purpose of testing of our product. The Kaspersky Lab has a tradition — to let out anti-virus SDK for all imaginable platforms if only there was something there, capable to compile a code on C. Respectively, SDK are necessary anti-virus bases which in spite of the fact that they are uniform for all products, nevertheless should be tested — for an error case in SDK, or the loader of bases, or some features of a platform, or … Generally, one million reasons. And that we learned about problems a little earlier, than from new cases in support, tens of pieces of iron checking each set of anti-virus bases for working capacity stand the last line of defense.

That is, not possibilities of AEWIN on work with a network, and only its essence in the form of MIPS/Linux were of interest. The problem was that the piece of iron did not provide any adequate accession. All that was offered to me — console port, telnet and any dhcp.

Unfortunately, the most terrible concerns were not vain. The device had no permanent storage, and it lived only from inclusion before reset, every time developing a referensny image.

Total, that it was necessary for me. To teach to receive the address on DHCP, to teach her to accept connections on SSH and to try not to break on the road.

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Archlinux for the smallest (Part 1)

1 year, 9 months ago


Preface


I want to tell about the remarkable Archlinux Linux-distribution kit and to spend you from an explanation of ideology of a distribution kit, before creation of a full-fledged working environment in it. In this, the first part, I on the example of Ubuntu will tell about merits and demerits of system and briefly I will tell about the basic concepts of a distribution kit and in the principles of its work. The rest — in the following parts.

This article means that you have an experience in work in Linux-systems as Archlinux rather difficult distribution kit for beginners. I will accompany all text with comparisons with the Ubuntu distribution kit. Ubuntu — because the most popular and the distribution kit differing from Archlinux most radically. I sacredly hope that it will help to acquire more simply information to the reader.

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Check of Wine: A year later

1 year, 10 months ago

Slightly more than a year ago for writing of article about verifications of the project with the help of PVS-Studio the Wine project has been taken. Article is written, authors have been notified and even have asked the full report of check by the analyzer, on what have received affirmative answer. Recently we were written by one of developers of the project. In article it will be told about our communication, the done work of design team of the Wine project on improvement of code and that else it is necessary to make.

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4 ways to write to the secure page

1 year, 10 months ago
Execution of record on hardware write-protected memory address in architecture of x86 means. And how it becomes in the Linux operating system. And, naturally, in Linux kernel mode because in user space, such tricks are prohibited. Happens, whether know, irresistible desire to write in the protected area … when you sit down to write virus or trojan …

Description of problem


… and if it is serious, the record problem in write-protected pages of random access memory arises from time to time when programming modules of kernel under Linux. For example, at modification of the selector table of system calls of sys_call_table for modification, embedding, implementation, substitutions, interception of system call — in different publications call this action on miscellaneous. But not only for these purposes … In very summary the situation looks so:

  • In architecture of x86 there is protection gear which in attempt of record in write-protected pages of memory leads to excitation of exception.
  • Access rights to the page (permission or prohibition of record) are described beaten _PAGE_BIT_RW (1) in the structure corresponding to this page like pte_t. Reset of this bit forbids record in the page.
  • From the processor control by protection of record the bit of X86_CR0_WP (16th) of the system managing register CR0 manages — at the set this bit attempt of record in the write-protected page excites exception of this processor.

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ZFS on CentOS: correction of mistakes

1 year, 10 months ago
As I for a long time use ZFS (since OpenSolaris), and is very happy with this FS in Linux, despite its "not orthodox" license, have naturally read fresh article about installation of this FS on CentOS.

Having noticed in the manual to feat fulfillment some errors, has decided not to pass by as I do it usually. Unfortunately, in comments I cannot answer, for the obvious reason.

Correction of mistakes, and some useful tips under cat.

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The CentOS installation on ZFS in UEFI

1 year, 10 months ago


Has decided to try here the other day ZFS, and detailed and simple manual as to carry out it on CentOS has not found, has decided to correct situation. Besides there was a wish to set all this in the EFI mode. — not to stand still? And at the same time to understand for itself as DKMS, and also aspects of the manual RPM-based installation of distribution kits works.

ZFS has been selected too not accidentally as by this machine it was going to unroll hypervisor and to use zvol for storage of images of virtual computers. I wanted something bigger than program raid + lvm or simple file storage of images, something on similarity of ceph, but for one host it is too bold. Running forward I will tell that I was very pleased with this file system, its productivity and all its counters.

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The PROXY installation of the server on DD-WRT

1 year, 10 months ago
How to set DD-WRT on router I will not tell, about it it is full of articles. And here is how to set proxy, has not found distinct manual. Here also has decided to write the.

In order that without prepyatstvenno to set the third-party software on your DD-WRT to be necessary occasional seat which in router is usually not enough. Therefore it is necessary to connect to it additional flash card. As in my case the router will distribute the Internet with 3G of the modem, and USB port at me on router 1 and not to be fooled with USB hub, I have inserted microSD flash card directly in 3G the modem.

The majority 3G of modems from Huawei it have the connector for microSD. I have Huawei E1820 modem from Megafon.

And so, in order that the flash card worked as storage under files of DD-WRT system, and it is Linux in pure form, it is necessary to create at first some sections on our flash card, and to format them in file system of ext3. Not everyone has near at hand linux therefore I will show method as it can be made under Windows.

For a start we will install the driver which allows to work with this file system. It is possible to download with sourceforge.net/projects/ext2fsd — Installation of this driver is optional, it is necessary only if you want to work with flash card contents in Windows. To mark disk, we will download the EaseUS Partition Master Home Edition program which is available here: www.partition-tool.com/download.htm. The program free for house use and quite is suitable for our task.

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The maker-up's life in Linux

1 year, 10 months ago
Most of fronted-developers, use Windows or OS X OS due to the lack of full-fledged Photoshop. But how to be that who is not indifferent to Nix to systems? Now also we will try to find out, I ask the interested under kat.

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LinuxCon + CloudOpen + Embedded LinuxCon Europe 2015: as it was

1 year, 10 months ago
Once a year passes event which all who though something knows about Linux dream to visit in Europe. Event which collects round itself the biggest community ever existing on this planet. Community of enthusiasts, hackers, engineers, programmers, administrators, corporate bosses, all those who has work and hobby thanks to Linux and open source. We in STC Metrotek have got used to share knowledge and to receive them therefore such could not be passed. Ladies and gentlemen, welcome to Dublin on the threefold conference LinuxCon + CloudOpen + Embedded LinuxCon Europe 2015!


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Supervisord and forever are not necessary any more. Systemd

1 year, 10 months ago
In article it will be a question of systemd which has entered Debian 8 jessie. I write about Debian because I use it. I write about systemd not because his fan, but some things really please me.

So why supervisord and forever are not necessary any more?

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