Discuss August 2018

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80 participants
77 discussions

vdo statustics on Dedup?
by david 31 Aug '18

31 Aug '18

Folks I've started to use "vdo" instead of zfs in Centos 7. I hope this is a wise decision. However, I'm a bit mystified in decoding the "vdostats" output. I'd like to figure out how well deduplication is working. One measure would be to find two numbers: L = How many bocks are in use as reported to tools like df P = How many actual blocks are in use. Then a value such as L/P, which can never be less than 1, would be interesting. If I have typically four copies of everything, I'd expect to see L/P close to 4.00. What two numbers, in the "vdostats" do this if any? David

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bash completion in C7
by wwp 31 Aug '18

31 Aug '18

Hello there, while bash completion was working great to me in CentOS6, since I'm using C7 I spend my day stuck on completion not working the way it should. The bad situations I'm facing are: - it doesn't expand *foo whereas there are *foo-named files in current dir, for instance: # rm *foo will show nothing whereas there's a file barfoo in curdir. - completion takes 10 sec to propose me something, I don't have an example right here but I'd prefer no completion instead of a completion that hangs for more than 3 sec. I don't care much about command-specific completion (command --switches and so on), but it generally fails in listing files in curdir, that is a huge fail to me. I have this installed: bash-4.2.46-30.el7.x86_64 bash-completion-2.1-6.el7.noarch bash-completion-extras-2.1-11.el7.noarch Didn't touch global or user prefs around bash completion if there are. Am I missing something or is it just an itchy fail, real pain in the *ss? Regards, -- wwp

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TUTORIAL: How to Install Apache Web Server in CentOS 7.5 (1805) Linux in Amazon AWS Cloud with URL/HTTP/HTTPS Redirection
by Turritopsis Dohrnii Teo En Ming 31 Aug '18

31 Aug '18

TUTORIAL: How to Install Apache Web Server in CentOS 7.5 (1805) Linux in Amazon AWS Cloud with URL/HTTP/HTTPS Redirection AUTHOR OF THIS TUTORIAL: MR. TURRITOPSIS DOHRNII TEO EN MING (ZHANG ENMING) @ TIME TRAVELLER AGE: 40 YEARS OLD COUNTRY OF RESIDENCE: SINGAPORE DATE: 30TH AUGUST 2018 THURSDAY TIME: 10:49 AM SINGAPORE TIME Greenwich Mean Time+8 1. Sign up for Amazon AWS Cloud or Google Cloud Platform or Microsoft Azure Cloud or Ali Baba Cloud account (your preference). 2. Login to Amazon AWS Management Console. 3. Click EC2 under Compute. 4. Click Elastic IPs under Network and Security. 5. Click Allocate New Address. 6. Click the Allocate button. 7. You will receive a permanent public IPv4 address from Amazon AWS Cloud, eg. 18.223.148.223. Alternative IPv4 address: 18.220.9.93. IPv6 address is not applicable. 8. Click Instances under INSTANCES. 9. Click Launch Instance. 10. Click AWS Marketplace. 11. Search for CentOS in the Search box. Press ENTER. 12. Select CentOS 7 (x86_64) - with Updates HVM 1805_1 Amazon Machine Image (AMI). 13. Click Continue. 14. Select General purpose, t2.micro, 1 vCPU, 1 GB RAM (FREE TIER ELIGIBLE). 15. Click Next: Configure Instance Details. 16. Select Network: <Your VPC network>. 17. Select Subnet: <Your subnet> | Public subnet | us-east-2a. 18. Click Protect against accidental termination. 19. Click Next: Add Storage. 20. Click Next: Add Tags. 21. Click Next: Configure Security Group. 22. Click Select an existing security group. 23. Select VS_SG (Virtual Server Security Group). 24. Click Review and Launch. 25. Click Launch. 26. Select a Secure Shell (SSH) key pair. 27. Click Launch Instances. 28. Click Elastic IPs under Network and Security. 29. Select the Elastic IP 18.223.148.223. 30. Click Actions. 31. Click Associate address. 32. Select the Instance you have created previously. 33. Click Allow Elastic IP to be reassociated if already attached. 34. Click Associate. 35. Open Putty/SSH client and login to CentOS 7.5 (1805). 36. Login as username centos. 37. Sign Out from Amazon AWS Management Console. 38. Install Apache web server with the Secure Sockets Layer (SSL) module: sudo yum install httpd mod_ssl 39. Start the Apache web server process: sudo /usr/sbin/apachectl start 40. Visit and test your web server at 18.223.148.223 Using Google Chrome. 41. You should see an Apache Web Server test page. 42. Install the nano text editor in Linux: sudo yum install nano 43. Go to the main Apache web server configuration directory: cd /etc/httpd/conf 44. Edit the main Apache web server configuration file: sudo nano httpd.conf 45. Append the following code to the end of httpd.conf: <VirtualHost *:80> ServerName blogger.teo-en-ming.com Redirect / https://tdtemcerts.blogspot.sg </VirtualHost> Alternative Code: <VirtualHost *:80> ServerName wordpress.teo-en-ming.com Redirect / https://tdtemcerts.wordpress.com </VirtualHost> 46. Restart the Apache web server process: sudo /usr/sbin/apachectl restart 47. Open an Internet Protocol Security (IPsec) Virtual Private Networking (VPN) connection to your corporate network using Shrew Soft VPN client. 48. Open a Remote Desktop Connection to your Windows Server 2019 Active Directory Domain Controller. 49. Under Server Manager, click Tools. Then Click DNS (Domain Name Service). 50. Click Forward Lookup Zones. 51. Click TEO-EN-MING.COM 52. Right Click, select New Host (A or AAAA). 53. Fill in Hostname: blogger 54. Fill in IP address: 18.223.148.223 55. Click Add Host. 56. Alternative DNS Host Record: Fully Qualified Domain Name (FQDN): WORDPRESS.TEO-EN-MING.COM IP address: 18.220.9.93 57. Test http://blogger.teo-en-ming.com. It should redirect to https://tdtemcerts.blogspot.sg 58. Alternative test: http://wordpress.teo-en-ming.com. It should redirect to https://tdtemcerts.wordpress.com 59. Go to Apache web server alternative configuration directory: cd /etc/httpd/conf.d 60. Edit the Apache web server Secure Socket Layer (SSL) configuration file: sudo nano ssl.conf 61. Find the section that says <VirtualHost _default_:443> 62. Insert the following code: ServerName blogger.teo-en-ming.com Redirect / https://tdtemcerts.blogspot.sg Alternative Code: ServerName wordpress.teo-en-ming.com Redirect / https://tdtemcerts.wordpress.com 63. Restart the Apache web server process: sudo /usr/sbin/apachectl restart 64. Test https://blogger.teo-en-ming.com. It should redirect to https://tdtemcerts.blogspot.sg 65. Alternative test: https://wordpress.teo-en-ming.com. It should redirect to https://tdtemcerts.wordpress.com 66. USEFUL REFERENCES: (A) Article: Install Apache and PHP on CentOS 6 Link/URL: https://support.rackspace.com/how-to/centos-6-apache-and-php-install/ (B) Article: How To Create Temporary and Permanent Redirects with Apache and Nginx Link/URL: https://www.digitalocean.com/community/tutorials/how-to-create-temporary-an… 67. Exit Putty/SSH client. 68. END OF TUTORIAL. ===BEGIN SIGNATURE=== Turritopsis Dohrnii Teo En Ming's Academic Qualifications as at 30 Oct 2017 [1] https://tdtemcerts.wordpress.com/ [2] http://tdtemcerts.blogspot.sg/ [3] https://www.scribd.com/user/270125049/Teo-En-Ming ===END SIGNATURE===

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Re: [CentOS] Mail has quit working
by Richard 30 Aug '18

30 Aug '18

> Date: Monday, August 27, 2018 09:57:01 -0400 > From: TE Dukes <tdukes(a)palmettoshopper.com> > >> From: CentOS [mailto:centos-bounces@centos.org] On Behalf Of >> centos--- via CentOS >> Sent: Monday, August 27, 2018 9:31 AM >> >> On 08/27/2018 09:05 AM, TE Dukes wrote: >> > >> > >> > Thanks again! I still think it's a mail issue. I can't get mail >> > using usermin either. >> > >> > Think I'm going to remove the TLS stuff from postfix main.cf >> > that I added yesterday and retry. >> >> If I missed this further up thread my apologies - is SELinux >> enabled and are there any relevant exceptions being logged? > > Pretty sure SELinux is turned off unless it got turned on without my > knowledge through an updtate/upgrade. > > I removed the TLS lines from main.cf I added last night and > remotely did a reboot from here at work. > > Mail is again working!! I am skeptical to mark this thread solved > as I thought it was solved back in July. > > I think, removing my ISP's DNS servers from resolve.conf was the > fix, could be removing IPV6 from etc/hosts. Might put it back in > just to see. > As I indicated earlier, removing those lines from your postfix config will have no impact on your ability to reach your roundcube instance. Unlike the windowz world, you mostly don't need to "reboot" a machine after making changes to a service (e.g., your postfix config change). An unnecessary reboot can bring in many issues so makes debugging a problem difficult. Instead, restart the service in question (often a reload is all that's needed, but a service restart generally doesn't hurt in a single/lower user environment). Unless you are VPN-ing (or equiv) my sense is that you are currently getting to your mail (roundcube) from outside your network. Earlier, when it wasn't working, my sense was that you were inside. If that's true you can't really tell if your issue has been resolved as you are coming at things from different network directions.

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missing CESA-2018:2571 Important CentOS 6 bind Security Update
by Ulf Volmer 30 Aug '18

30 Aug '18

Hello, i'm running bind on an up to date CentOS 6.10 and missing the bind update from the announcement above. [root@fw ~]# yum list bind Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile * epel: ftp.nluug.nl Installed Packages bind.x86_64 32:9.8.2-0.68.rc1.el6 @base is there is something wrong on my side? Or with the CentOS- repo? (My repo config is on https://cloud.u-v.de/index.php/s/ksNcosfmBrN57SQ ) best regards Ulf

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SecureBoot : rolling out new shim pkgs for CentOS 7.5.1804 in CR repository - asking for testers/feedback
by Fabian Arrotin 30 Aug '18

30 Aug '18

When we consolidated all CentOS Distro builders in a new centralized setup, covering all arches (so basically x86_64, i386, ppc64le, ppc64, aarch64 and armhfp those days), we wanted also to add redundancy where it was possible to. The interesting "SecureBoot" corner case came on the table and we had to find a different way to build the following packages: - shim (both signed and unsigned) - grub2 - fwupdate - kernel The other reason why we considered rebuilding it is that the cert we were using has expired : curl --location --silent https://github.com/CentOS/sig-core-SecureBoot/raw/master/CentOS_7/kernel/SO… | openssl x509 -inform der -text -noout|grep -A2 Validity While technically it doesn't really matter for Secureboot itself, it was better to get a new key/cert rolled-in and use the new one for new builds. That's where it's interesting as because shim embeds the certs in the Machine Owner Key (MOK), and that each other component used in the boot chain is validated against that (so grub2 first, then kernel and kernel modules) that means that once deployed , the new shim would not be able to boot previous grub2/kernel. But there is a solution for that : instead of "embedding" only the new cert, we can have both the old one and new one, permitting us to still boot older kernels but also the new ones we'll build/push soon (built on the new build system), and that's what we used for that new shim package. That's where we'd like you (SecureBoot users) to give us feedback about that new shim pkg. It was already validated on some hardware nodes, passed some QA tests, but we'd prefer to have more feedback. Worth noting that such rebuild has also a patch that should fix an issue we had with shim not allowing to import key in MOK through mokutil (see https://bugs.centos.org/view.php?id=14050) How can you test ? If you're using UEFI with SecureBoot enabled , we have signed/pushed those pkgs to the CR repository (see https://wiki.centos.org/AdditionalResources/Repositories/CR) That repo is by default disabled, but following command would let you update shim : yum update shim --enablerepo=cr Then reboot and it should work like before, so validating the boot chain (while still using grub2/kernel packages signed with previous key) We'd appreciate feedback on this list, or #centos-devel on irc.freenode.net I'd like to thank Patrick Uiterwijk and Peter Jones for their help for the patch and validation for that shim -- Fabian Arrotin The CentOS Project | https://www.centos.org gpg key: 56BEC54E | twitter: @arrfab

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Re: [CentOS] Stuck on loading of CentOS
by Dhanasekaran Balakrishnan 29 Aug '18

29 Aug '18

Hi, Yes nvidia driver is installed in the computer. I am not sure how my colleague did this and presently he is not in my lab. -Dhana -- PhD Student, Bionanoscience and Biochemistry Laboratory (Heddle Lab), Malopolska Center of Biotechnology, Jagiellonian University, Krakow, Poland.

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grub.cfg
by Steffan A. Cline 29 Aug '18

29 Aug '18

I ran into something with a recent batch of updates on CentOS 7. It seems that possibly one of the kernel updates running dracut changed all of the volume groups in the grub.cfg file making the system unable to boot until I manually edited each line putting it back to the way it was originally. My volume group is called vg_h1 but it changed them all to the default “centos”. Is there a config somewhere I need to edit so this never happens again? Steffan A. Cline steffan(a)hldns.com 602-793-0014

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Kickstart file for software raid
by Jerry Geis 29 Aug '18

29 Aug '18

I am using a kickstart file for CentOS 7 raid / --device=md0 --fstype="xfs" --level=1 --useexisting raid /home --noformat --device=md1 --level=1 --useexisting It is erroring out on the --useexisting. The exact text is: RAID volume "0" specified with "--useexisting" does not exist. What did I do wrong? Jerry

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C7, system-auth-ac, and authconfig
by mark 29 Aug '18

29 Aug '18

I read the clear-as-mud docs, and it appears that if we want to modify system-auth-ac, we can create a local, and point system-auth to it. Howver.. in the default, I see auth [success=3 default=ignore] pam_succeed_if.so service notin login:gdm:xdm:kdm:xscreensaver:gnome-screensaver:kscreensaver quiet use_uid Now, we'd like to add sudo to that list. Does anyone know *where* authconfig gets that list in the first place? I haven't been able to find anything yet, and I've been looking. mark

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Discuss August 2018