Category: linux

PENDING SECTOR COUNT

Ordinarily hard disks operate transparently. Any problems are handled by the drive logic. Disks in use may find problem sectors or tracks and they then map spare area into the block number table when the error correction cannot cope. badblocks -sv -b 512 <device-name> If the disk is one of the newer 4K sector designs, …

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WHITELIST SECURITY

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We have used whitelist security for protecting our servers for a very long time. More recently we have seen Linus Torvads in the media over securing a server.  Version 4.15 of the kernel will now start mainstream whitelists. Securely managing memory for possible malware is something that is sorely needed for Linux. Sadly a lot …

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UPDATE FAILURE

Today when managing our VM running Ubuntu 16.04 we ran across this rather serious fault. We rebooted the VM immediately in principle. Hopefully Canonical can fix this problem so that cloud users can carry on. The VM runs MySQL to handle webapps and it works fine.   sudo apt-get update Hit:1 http://azure.archive.ubuntu.com/ubuntu xenial InRelease Get:2 …

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KERNEL 4.12

Linux Kernel 4.12 has been released. It may take some time for various distributions to get it ready for installation. Support for AMD Vega Support for NVIDIA Pascal Two new I/O schedulers Intel Atomic Mode is now enabled by default Two new I/O schedulers have also found a place in Linux kernel. These schedulers are …

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KERNEL 4.4.0 UPDATE

If you are using Linux there is a large update to the kernel with 4.4.0 to deal with some problems in the heap. A security audit noticed that elevated applications could access sensitive areas in the heap potentially causing some security problems. The stack used my processors can be configured to be range bound which …

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SHA-1 COLLISION

It took several years but researchers have finally beat SHA-1 and found it is easily possible to have 2 different documents with the game hash value. SHA-1 was officially deprecated by NIST in 2011 SHA-1 is widely used with HTTPS certificates in addition to many other applications. SHA-1 is also widely used for file integrity. Consider …

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UBUNTU FORUM

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Given the problems we have experienced with the Ubuntu forum is why this site exists. Over time more and more general self-help articles will be posted. The original post has been removed and inquiries have failed.  Security is a serious problem which needs more attention. We are aware that in 2016, a full 20% of …

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KERNEL 4.10 RELEASED

Linus Torvalds has released version 4.10 of the Linux kernel. This will find it’s way into everyone’s distribution as time permits. THE POST On the whole, 4.10 didn’t end up as small as it initially looked. After the huge release that was 4.9, I expected things to be pretty quiet, but it ended up very much a …

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WEB SERVER PERFORMANCE

Web servers today are a real mixed bag as prices for services have come down so much. To run a successful server swarm needs some resources. Blade servers are the most common hardware available. Most individual machines can be equipped with at least 128GB of memory. With dual sockets and modern 8 core 16 core …

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CHOWN

Chown is the Linux tool to change ownership of a file or directory. The general chown user group filename syntax is all that is needed.. $ sudo su # cd /var/mail # for x in * # do # chown $x $x # done # exit can fix a mail system that has ownership problems …

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