Discuss April 2018

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90 participants
59 discussions

CentOS 7 + Xfce + GDM : disable "switch user" ?
by Nicolas Kovacs 07 Apr '18

07 Apr '18

Hi, I have CentOS 7 + Xfce + GDM installed on all our local school's desktop clients. I'd like to disable the "switch user" menu entry, since our desktop clients have a relatively limited amount of RAM. Most users tend to use the "switch user" functionality to log off, and at the end of the day, the computer has no RAM left. I know there is a way to disable this functionality, I vaguely remember having it done a few years ago on Slackware. Any suggestions ? Niki -- Microlinux - Solutions informatiques durables 7, place de l'église - 30730 Montpezat Site : https://www.microlinux.fr Blog : https://blog.microlinux.fr Mail : info(a)microlinux.fr Tél. : 04 66 63 10 32

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Unable to access network from docker container
by H 07 Apr '18

07 Apr '18

I have recently installed docker and playing around with it. On a CentOS 7 machine, however, I am unable to get access to the outside internet, thus yum ... fails. The host machine runs fine. I am wondering if there are some networking setting on the host I need to modify to allow the docker container to connect to the outside?

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invalid mirror .host-engine.com
by Walter H. 06 Apr '18

06 Apr '18

Hello, how can I prevent of using these mirrors? # yum clean all Loaded plugins: fastestmirror, security Cleaning repos: base extras updates Cleaning up Everything Cleaning up list of fastest mirrors # yum update Loaded plugins: fastestmirror, security Setting up Update Process Determining fastest mirrors * base: centos.den.host-engine.com * extras: centos.den.host-engine.com * updates: centos.den.host-engine.com http://centos.den.host-engine.com/6/os/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://centos.den.host-engine.com/6/os/x86_64/repodata/repomd.xml: (28, 'Operation too slow. Less than 1 bytes/sec transfered the last 30 seconds') Trying other mirror. base | 3.7 kB 00:00 http://centos.den.host-engine.com/6/extras/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://centos.den.host-engine.com/6/extras/x86_64/repodata/repomd.xml: (28, 'Operation too slow. Less than 1 bytes/sec transfered the last 30 seconds') Trying other mirror. extras | 3.4 kB 00:00 http://centos.den.host-engine.com/6/updates/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://centos.den.host-engine.com/6/updates/x86_64/repodata/repomd.xml: (28, 'Operation too slow. Less than 1 bytes/sec transfered the last 30 seconds') Trying other mirror. is there a way of setting up a DNS ZONE where requests to this domain get somewhat like 'not exist'? Thanks, Walter

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Re: [CentOS] GnuPG 2.0.16?
by Karl Vogel 06 Apr '18

06 Apr '18

>> On Thu, 29 Mar 2018 10:53:05 -0700, >> Kay Schenk <kay.schenk(a)gmail.com> said: K> Does anyone know where I can find GnuPG 2.0.16 for CentOS 6.9 32-bit? Do you want something that old? 2.0.17 came out in 2011. I run Oracle Linux 6.9 (basically RHEL without the trademarks) -- if you're comfortable building from source, GnuPG-2.2.5 wasn't hard. This is what I did: Download files: site='https://gnupg.org/ftp/gcrypt' curl $site/libassuan/libassuan-2.5.1.tar.bz2 curl $site/libassuan/libassuan-2.5.1.tar.bz2.sig curl $site/libgcrypt/libgcrypt-1.8.2.tar.bz2 curl $site/libgcrypt/libgcrypt-1.8.2.tar.bz2.sig curl $site/libgpg-error/libgpg-error-1.28.tar.bz2 curl $site/libgpg-error/libgpg-error-1.28.tar.bz2.sig curl $site/libksba/libksba-1.3.5.tar.bz2 curl $site/libksba/libksba-1.3.5.tar.bz2.sig curl $site/npth/npth-1.5.tar.bz2 curl $site/npth/npth-1.5.tar.bz2.sig curl $site/gnupg/gnupg-2.2.5.tar.bz2 curl $site/gnupg/gnupg-2.2.5.tar.bz2.sig Check the tarballs against GPG signatures and unpack. Build libraries first: export CC=gcc export CXX=g++ export CFLAGS=-O2 export LDFLAGS="-L/usr/local/lib" export CPPFLAGS="-I/usr/local/include" dest=/usr/local cd /path/to/libassuan-source ./configure --prefix=$dest --mandir=$dest/man make && make check && make install && make clean cd /path/to/libgcrypt-source ./configure --prefix=$dest --mandir=$dest/man make && make check && make install && make clean cd /path/to/libgpg-error-source ./configure --prefix=$dest --mandir=$dest/man make && make check && make install && make clean cd /path/to/libksba-source ./configure --prefix=$dest --mandir=$dest/man make && make check && make install && make clean cd /path/to/npth-source ./configure --prefix=$dest --mandir=$dest/man make && make check && make install && make clean Build gnupg -- this was more interesting because I needed the realtime library (librt) as well as a local ncurses library (libncursesw) to make readline stuff work. You may not need this, depending on how your libraries are set up: export CC=gcc export CXX=g++ export CFLAGS=-O2 export LDFLAGS="-L/usr/local/lib -L/usr/lib64" export LIBS="-lreadline -lncursesw -lrt" export CPPFLAGS="-I/usr/local/include" dest=/usr/local cd /path/to/gnupg-source ./configure --prefix=$dest --mandir=$dest/man [change config.h to hold "#undef HAVE_INOTIFY_INIT" unless you have a very recent release of inotify sources] make && make check && make install && make clean It's a little tedious but it works. -- Karl Vogel / vogelke+unix(a)pobox.com / I don't speak for the USAF or my company About as useful as telling Indiana Jones to look both ways before crossing the street. --comment about Amazon IT documentation

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/lib/firmware/microcode.dat update on CentOS 6
by Valeri Galtsev 05 Apr '18

05 Apr '18

Dear All, An update just brought on my CenOS 6 boxes updated microcode.dat files: /lib/firmware/microcode.dat Does anybody know off hand what (how critical) is that, as, if it is related to most famous these days trouble with CPU hardware, I will need to reboot relevant boxes to have new microcode loaded. But if it is not that critical, it can wait till next reboot. Thanks a lot and apologies for laziness (not looking into details of this particular update myself). Valeri ++++++++++++++++++++++++++++++++++++++++ Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247 ++++++++++++++++++++++++++++++++++++++++

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Centos 7 LAPP setup PHP 5 vs 7
by Gary Stainburn 05 Apr '18

05 Apr '18

Another questions regarding my new server setup. As with the Postgresql setup, different pages describing setting up a Centos LAPP server have differing opinions about PHP versions. The default distro's appear to still be installing PHP5 while some sites instruct on how to install PHP7. I am porting my old server which must be 10 years old, running Fedora 9 and PHP5 onto the new server, so presumably sticking with PHP5 would be the easier option. However, I am looking to give my new server as long a life as possible, so should I instead be looking at PHP7? I have literally thousonds of lines of PHP code on my existing box. How much head ache am I going to have porting into either of the two new platforms? How much difference would PHP5 vs PHP7 be? Opinions please

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Centos 7 LAPP setup Postgresql version and setup
by Gary Stainburn 05 Apr '18

05 Apr '18

Hi all, I've got a nice shiny new server which I'm going to build as a LAPP platform. I've just had a quick look for suitable instructions on the best way to configure it and I have a few questions. There are many hits, some better than others. (It is replacing a Fedora 9 server so I'm expecting to have lots of *fun*) 1) 9.2 vs 9.5 Some of the instruction pages I've found install using the standard repositories and install version 9.2 (?) while some others add a postgresql repo and install 9.5 What are people's opinions? In the long term, and I going to have more admin hassle with one over the other? Will porting schemas including stored functions in pl/psql from 8.3 be easier / better with one version over the other? 2) network vs sockets I read somewhere that connecting Apache / PHP to Postgresql is faster if you use sockets rather than usling the loopback i/f. Is this correct? If it is correct, what is the correct connect string if I use the 9.2 or 9.5 RPM's as described above? There seems to be lots of Google content about sockets not working. Is it really that hard? (I use pg_pconnect() to do the connecting)

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memory cgroup max_usage_in_bytes question
by Stijn De Weirdt 05 Apr '18

05 Apr '18

hi all, can someone help explaining what we are seeing? it makes no sense to us. this is a host running centos 7.4 with 3.10.0-693.17.1 kernel, and it has 192GB of ram > [] free -b > total used free shared buff/cache available > Mem: 201402642432 14413479936 75642777600 48586752 111346384896 185689632768 > Swap: 21474832384 31961088 21442871296 > [] cat /sys/fs/cgroup/memory/memory.max_usage_in_bytes > 273102151680 how can the max be so much higher than total, and this is not even memsw? either we're very tired and are overlooking something obvious, or there's something new to be learned ;) many thanks, stijn

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What is the universal (world wide) understanding behind degaussing harddisks?
by Turritopsis Dohrnii Teo En Ming 02 Apr '18

02 Apr '18

Good evening from Singapore! The foremost question which I want to ask is, what is the universal (world wide) understanding behind degaussing hard drives? I work for No Secrets Agency (NSA) Pte Ltd (fictitious company name used). My sales manager Edward Joseph Snowden (fictitious individual name used) had *promised* our customer Leave Me in the Lurch (S) Pte Ltd (fictitious company name used) that we would "DEGAUSS" their hard disks after the PC replacement and data migration exercise for 15 trillion PCs (fictitious number used). PC = Personal Computer, which includes desktops and laptops Last Friday, I had already reflected to my sales manager Edward Snowden that since we are definitely NOT going to wipe our customer's data by using strong and powerful magnets (physical means), should I send an email to the IT Administrator of our customer Lady Gaga (fictitious individual name used) asking her which data sanitization method (by software means) I should use? My sales manager Edward Snowden had quickly deflected my concerns (that is, wanting to send an email to our customer Lady Gaga asking her which data sanitization method I should use). I had brought up to the sales manager Edward Snowden a number of data wiping methods by software means last Friday. (1) Very very simple 1-pass data wiping, quickest a. Using "sudo dd if=/dev/zero of=/dev/sda", overwriting harddisks from beginning to end with zeroes, where /dev/sda refers to the 500 GB harddisk, not /dev/loop0 and not /dev/sdb which refers to the bootable live operating system on thumb drive b. Using "sudo dd if=/dev/urandom of=/dev/sda", overwriting harddisks from beginning to end with random data, where /dev/sda refers to the 500 GB harddisk, not /dev/loop0 and not /dev/sdb which refers to the bootable live operating system on thumb drive Any bootable Live CD/DVD/flash media could do it. (2) 3-pass U.S. Government/Department of Defense (DoD) standard (DoD 5220.22-M) Certified commercial software required (3) 7-pass U.S. Government/Department of Defense (DoD) standard (DoD 5220.22-M) Certified commercial software required (4) 35-pass Gutmann method, slowest Certified commercial software required All these was last Friday. In the midst of our argument over the cellular network "just now", my sales manager Edward Snowden tried to cover up himself by suddenly and unexpectedly making an excuse that he had told me last Friday I was supposed to wipe user data only, not the operating system! If he had wanted me to wipe user data and retain/keep the Windows operating system, he should simply have told me to Reset the PC (for Windows 10 only) or use a =secure File Shredder=! For Windows 7, you can still wipe user data and preserve the operating system by using the Recovery Partition. On Lenovo desktops, press and hold F11 when Windows 7 is starting and reset to factory defaults. I had advised my sales manager Edward Snowden not to use BIG WORDS like "degaussing the harddisk" and market to the customer using these big words. Any person who sees the word "degauss" would have understood it to mean sanitize *ALL* data on the harddisk straight away and without question. Please refer to Figure 1. Exhibit A below for the "degaussing" instructions communicated to me by my sales manager Edward Snowden. Please click the link below. URI: https://i.imgur.com/bGOMyVs.png Please advise. Thank you very much. Regards, Mr. Turritopsis Dohrnii Teo En Ming Systems and Network Engineer Republic of Singapore 2nd April 2018 Monday 9:35 PM Singapore Time GMT+8

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Discuss April 2018