Discuss March 2021

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73 participants
55 discussions

KVM vs. incremental remote backups
by Nicolas Kovacs 04 Apr '21

04 Apr '21

Hi, Up until recently I've hosted all my stuff (web & mail) on a handful of bare metal servers. Web applications (WordPress, OwnCloud, Dolibarr, GEPI, Roundcube) as well as mail and a few other things were hosted mostly on one big machine. Backups for this setup were done using Rsnapshot, a nifty utility that combines Rsync over SSH and hard links to make incremental backups. This approach has become problematic, for several reasons. First, web applications have increasingly specific and sometimes mutually exclusive requirements. And second, last month I had a server crash, and even though I had backups for everything, this meant quite some offline time. So I've opted to go for KVM-based solutions, with everything split up over a series of KVM guests. I wrapped my head around KVM, played around with it (a lot) and now I'm more or less ready to go. One detail is nagging me though: backups. Let's say I have one VM that handles only DNS (base installation + BIND) and one other VM that handles mail (base installation + Postfix + Dovecot). Under the hood that's two QCOW2 images stored in /var/lib/libvirt/images. With the old "bare metal" approach I could perform remote backups using Rsync, so only the difference between two backups would get transferred over the network. Now with KVM images it looks like every day I have to transfer the whole image again. As soon as some images have lots of data on them (say, 100 GB for a small OwnCloud server), this quickly becomes unmanageable. I googled around quite some time for "KVM backup best practices" and was a bit puzzled to find many folks asking the same question and no real answer, at least not without having to jump through burning loops. 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 Mob. : 06 51 80 12 12

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Migrating to nvme and expand
by Jerry Geis 02 Apr '21

02 Apr '21

I have older SATA disks (2 of them size 2T) in a software raid config running CentOS 7. /dev/md127 is / and xfs /dev/sda2 is swap /dev/md126 is /home and xfs I desire to get a new (single) NVME 4T disk. What is the correct way to copy the software raid to a single "new" NVME disk ? then expand the /home file system to All the remaining space? Thanks, Jerry

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Debuginfo for CentOS 8 Stream
by Matthew Saltzman 01 Apr '21

01 Apr '21

My CentOS 8 Stream installation is fully current. I did sudo debuginfo-install libgcc libstdc++ but the response I get is Could not find debuginfo package for the following installed packages: libgcc-8.4.1-1.el8.x86_64, libstdc++-8.4.1-1.el8.x86_64 Could not find debugsource package for the following installed packages: libgcc-8.4.1-1.el8.x86_64, libstdc++-8.4.1-1.el8.x86_64 If I do sudo dnf --enablerepo=debuginfo debuginfo-install libgcc libstdc++ I get CentOS Stream 8 - Debuginfo 35 kB/s | 7.6 kB 00:00 Errors during downloading metadata for repository 'debuginfo': - Status code: 404 for http://debuginfo.centos.org/8-stream/x86_64/repodata/repomd.xml (IP: 2620:52:3::12) Error: Failed to download metadata for repo 'debuginfo': Cannot download repomd.xml: Cannot download repodata/repomd.xml: All mirrors were tried What do I need to do to get these debuginfo packages? TIA. -- Matthew Saltzman School of Mathematical and Statistical Sciences Clemson University mjs AT clemson DOT edu

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Problem with mail server: stop flooding with fail2ban ?
by Nicolas Kovacs 31 Mar '21

31 Mar '21

Hi, My main mail server is running CentOS 7 with Postfix and Dovecot. Last week I was surprised to see that Postfix had some troubles on this machine, according to Icinga. I took a peek at the logs: # journalctl -p err Mar 28 04:37:02 sd-151768 postfix/smtpd[2786]: fatal: no SASL authentication mechanisms Mar 28 04:37:02 sd-151768 postfix/smtpd[2788]: fatal: no SASL authentication mechanisms Mar 28 04:37:02 sd-151768 postfix/smtpd[2790]: fatal: no SASL authentication mechanisms Mar 28 04:37:02 sd-151768 postfix/smtpd[2792]: fatal: no SASL authentication mechanisms Mar 28 04:37:02 sd-151768 postfix/smtpd[2794]: fatal: no SASL authentication mechanisms ... And in /var/log/maillog I found a tsunami of these: Mar 28 03:18:33 sd-151768 postfix/smtpd[29589]: warning: unknown[45.227.253.115]: SASL LOGIN authentication failed: UGFzc3dvcmQ6 Mar 28 03:18:33 sd-151768 postfix/smtpd[29589]: lost connection after AUTH from unknown[45.227.253.115] Mar 28 03:18:33 sd-151768 postfix/smtpd[29589]: disconnect from unknown[45.227.253.115] My first reaction was to manually ban the IP addresses / networks which caused the flood, using my firewall: # firewall-cmd --permanent --add-rich-rule="rule family='ipv4' source address='45.227.253.0/24' reject" # firewall-cmd --reload I'm already using fail2ban in conjunction with firewalld to prevent brute force SSH attacks. Q: can I use it in a similar configuration to stop Postfix from getting flooded and brought down to its knees? Thanks & cheers from the sunny South of France, 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 Mob. : 06 51 80 12 12

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nmcli
by Jerry Geis 31 Mar '21

31 Mar '21

under CentOS 7 - I use "alias" like eth1:0 for an alias network. Remove the file restart network - and back to normal. Now I am trying to us NetworkManager. I can 'add' the network fine. however - when I remove the network nmcli connection delete "Wired connection 2" ipv4.addr 192.168.1.58/22 it remove BOTH address and removes the "Wired connection 2" config file - and it reverts to DHCP not the other static address I had associated with "Wired connection 2". how do I just remove the single ADDRESS I added as an alias ? not the whole thing ? Thanks Jerry

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Cups - weird interaction with the Internet
by Frank Cox 30 Mar '21

30 Mar '21

I have Centos 6 machine that I use for a cups printer server. (Yes, I know, but it's working fine for what it's for at the moment.) My ISP lost its connection to the network that printer server is on. While the outside Internet service was unavailable I sent a print job to the printer on that server and nothing printed even though the print server and the machine I sent the job from are on the same lan and are actually connected to the same router. The job appeared to be sent from the originating machine (but timed out, as shown below), and running lpq and lpq -a on the server showed "no entries" (because it timed out for some reason). I did this a few times and even rebooted the server and always the same thing. Job sent, "no entries" on the server. The my ISP's connection came back and blammo! All of a sudden I got a ton of sheets printed, everything that I had been trying to print for the previous ten minutes. Here is what appears to be a relevant portion of the log on the machine that was sending the job to the print server: Mar 30 13:05:06 mutt cupsd[1443]: Started backend /usr/lib/cups/backend/implicit class (PID 951459) Mar 30 13:05:06 mutt cupsd[1443]: REQUEST localhost - root "POST /admin/ HTTP/1. 1" 200 245 CUPS-Add-Modify-Printer successful-ok Mar 30 13:05:07 mutt cupsd[1443]: Job completed. Mar 30 13:06:02 mutt cupsd[1443]: Job submission timed out. So what happened here? Why would cups care if it has a connection to the outside world when it's just printing a job sent to it from the local lan? The connection between the machine originating the print job and the print server timed out even though all of the relevant traffic was going over the lan. -- MELVILLE THEATRE ~ Real D 3D Digital Cinema ~ www.melvilletheatre.com

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qemu-kvm images of old Windows XP SP3
by David McGuffey 30 Mar '21

30 Mar '21

I have a Nikon slide scanner (very high quality) for which the software has not been updated. It last ran on WinXP SP3 and I was not able to get it to run under Win 7 and certainly not Win 10. Anyone know where I can obtain images of this old OS to run in CentOS 7 under kvm? Dave McGuffey

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installing gnome icons
by R C 29 Mar '21

29 Mar '21

Hello, is there a way to install "icons / themes" so one gets all the gnome icons in /usr/share/icons/gnome ? thanks, Ron

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CentOS-announce Digest, Vol 192, Issue 3
by centos-announce-request＠centos.org 27 Mar '21

27 Mar '21

Send CentOS-announce mailing list submissions to centos-announce(a)centos.org To subscribe or unsubscribe via the World Wide Web, visit https://lists.centos.org/mailman/listinfo/centos-announce or, via email, send a message with subject or body 'help' to centos-announce-request(a)centos.org You can reach the person managing the list at centos-announce-owner(a)centos.org When replying, please edit your Subject line so it is more specific than "Re: Contents of CentOS-announce digest..." Today's Topics: 1. CESA-2021:0992 Important CentOS 7 firefox Security Update (Johnny Hughes) 2. CESA-2021:0996 Important CentOS 7 thunderbird Security Update (Johnny Hughes) ---------------------------------------------------------------------- Message: 1 Date: Fri, 26 Mar 2021 18:11:51 +0000 From: Johnny Hughes <johnny(a)centos.org> To: centos-announce(a)centos.org Subject: [CentOS-announce] CESA-2021:0992 Important CentOS 7 firefox Security Update Message-ID: <20210326181151.GA4954(a)bstore1.rdu2.centos.org> Content-Type: text/plain; charset=us-ascii CentOS Errata and Security Advisory 2021:0992 Important Upstream details at : https://access.redhat.com/errata/RHSA-2021:0992 The following updated files have been uploaded and are currently syncing to the mirrors: ( sha256sum Filename ) x86_64: 67cc5f25f8e6a42f9536eb9dbe7e22e3fab22c55d87d37db23cb90136913067e firefox-78.9.0-1.el7.centos.i686.rpm 44600066daf3f3b57b9e269737e0b0dfcd410f3a524fbbd74aec3162d6f84f7c firefox-78.9.0-1.el7.centos.x86_64.rpm Source: bedd47ac6fc527b008c2ed93845707f248f2a8eae9ad4201508728e2b54283ad firefox-78.9.0-1.el7.centos.src.rpm -- Johnny Hughes CentOS Project { http://www.centos.org/ } irc: hughesjr, #centos(a)irc.freenode.net Twitter: @JohnnyCentOS ------------------------------ Message: 2 Date: Fri, 26 Mar 2021 18:12:50 +0000 From: Johnny Hughes <johnny(a)centos.org> To: centos-announce(a)centos.org Subject: [CentOS-announce] CESA-2021:0996 Important CentOS 7 thunderbird Security Update Message-ID: <20210326181250.GA5084(a)bstore1.rdu2.centos.org> Content-Type: text/plain; charset=us-ascii CentOS Errata and Security Advisory 2021:0996 Important Upstream details at : https://access.redhat.com/errata/RHSA-2021:0996 The following updated files have been uploaded and are currently syncing to the mirrors: ( sha256sum Filename ) x86_64: 412317b2522f388f60a8b9846d99020fa2c884e8557b0552ad09b4218e97803d thunderbird-78.9.0-3.el7.centos.x86_64.rpm Source: 9b3ff2329273f188e644f9e8fb481e12ff32397fac7f7f9b4a689aa99d84529b thunderbird-78.9.0-3.el7.centos.src.rpm -- Johnny Hughes CentOS Project { http://www.centos.org/ } irc: hughesjr, #centos(a)irc.freenode.net Twitter: @JohnnyCentOS ------------------------------ Subject: Digest Footer _______________________________________________ CentOS-announce mailing list CentOS-announce(a)centos.org https://lists.centos.org/mailman/listinfo/centos-announce ------------------------------ End of CentOS-announce Digest, Vol 192, Issue 3 ***********************************************

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Cloning bridged VMs : VirtualBox vs. KVM
by Nicolas Kovacs 26 Mar '21

26 Mar '21

Hi, (tl;dr : how can I clone a KVM-based bridged virtual machine and force a duplicate MAC address ?) Up until recently I've been using VirtualBox on my workstation to test various local setups. Usually I would setup a basic CentOS installation, and whenever I wanted to fiddle around, I would just clone that system and play around with it. So whenever I shot myself in the foot on that VM, I would simply erase it and start over again with a new clone. Think of it as a disposable VM. All my VMs under VirtualBox used bridged mode, so they were in the same network. And in my local proxy server, I have Dnsmasq that assigns static IP addresses and meaningful hostnames to these VMs. Here's what the corresponding lines in dnsmasq.conf look like: dhcp-host=08:00:27:00:00:01,suse-lp151,192.168.2.10 dhcp-host=08:00:27:00:00:02,suse-lp152,192.168.2.11 dhcp-host=08:00:27:00:00:03,ce7-server,192.168.2.12 dhcp-host=08:00:27:00:00:04,ce8-server,192.168.2.13 dhcp-host=08:00:27:00:00:05,ol7-server,192.168.2.14 dhcp-host=08:00:27:00:00:06,ol8-server,192.168.2.15 dhcp-host=08:00:27:00:00:07,rh7-server,192.168.2.16 dhcp-host=08:00:27:00:00:08,rh8-server,192.168.2.17 Over the last two weeks, I decided to migrate from VirtualBox to KVM even for local configurations and virtualized desktop configurations. So far, everything works nice... except one problem I can't seem to solve (yet). I'm using KVM in bridged mode, over a br0 bridge on my workstation. Like with VirtualBox, all my KVM virtual machines are part of my local 192.168.2.0/24 network. Unfortunately there is no way to simply make a perfect clone of a virtual machine using virt-manager. It insists on assigning my cloned VM a different MAC address. And whenever I want to manually create a NIC with the same MAC address as the original, Virtual Machine Manager tells me I can't do that. Same player shoot again. Now I know that is normally a good thing. You don't want MAC address conflicts in your network. But here's the thing: I don't intend to fire up both copies at once. As with VirtualBox, I only intend to use one VM at a time, for testing purposes. Now how can I "explain" this to Virtual Machine Manager without having to jump through burning loops ? Cheers, 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 Mob. : 06 51 80 12 12

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Discuss March 2021