Discuss May 2012

discuss@lists.centos.org

193 participants
203 discussions

XEN or KVM - performance/stability/security?
by Rafał Radecki 13 Jul '12

13 Jul '12

Hi all. I am currently building a small test cloud based on Eucalyptus 2.0.3 and CentOS 5.8 x64. I have a choice which hypervisor to use: KVM or XEN. KVM is the default in CentOS 6 but I have read also many good things (for example PV guest machines, isolation between Dom0 and DomU) about XEN. Key factors from my opint of view are: - stability (which one runs more smoothly on CentOS?) - performance (XEN PV/HVM(with or without pv drivers) vs KVM HVM(with or without pv drivers)) - security Could you share your experience in these areas? Best regards, Rafal Radecki.

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yum problem with glibc
by Timothy Murphy 08 Jun '12

08 Jun '12

Is anyone getting a yum update problem with glibc and glibc-common? I'm getting the error message ------------------------------- Error: Protected multilib versions: glibc-2.12-1.47.el6_2.12.x86_64 != glibc-2.12-1.47.el6_2.9.i686 ** Found 3 pre-existing rpmdb problem(s), 'yum check' output follows: bash-4.1.2-9.el6_2.x86_64 is a duplicate with bash-4.1.2-8.el6.centos.x86_64 glibc-common-2.12-1.47.el6_2.12.x86_64 is a duplicate with glibc- common-2.12-1.47.el6_2.9.x86_64 glibc-common-2.12-1.47.el6_2.12.x86_64 has missing requires of glibc = ('0', '2.12', '1.47.el6_2.12') ------------------------------- I've tried "rpm --rebuilddb" but that did not seem to help. Any suggestions or advice gratefully received. -- Timothy Murphy e-mail: gayleard /at/ eircom.net tel: +353-86-2336090, +353-1-2842366 s-mail: School of Mathematics, Trinity College Dublin

6 16

CentOS 6.2: suspending vim with ctrl-z and resuming with fg - stopped working
by Alexander Farber 08 Jun '12

08 Jun '12

Hello, pardon my chaotic question, but does anybody have an idea, why can't I suspend vim-enhanced-7.2.411-1.6.el6.x86_64 with a CTRL-Z, then execute few commands at my bash prompt and then get back to the vim session again with "fg"? It has stopped working at my CentOS 6.2 machine (I haven't noticed exactly when) but works fine with CentOS 5.x. I'm using PuTTY to login to both. The error message I get is: afarber@www:~> fg sudo vim test.pl ~ [1]+ Stopped sudo vim test.pl (and nothing comes up) Thank you Alex

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Upgrading FC2 to CentOS 5.* - anyone second this?
by Max Pyziur 03 Jun '12

03 Jun '12

Greetings, I *do* still have an FC2 box. Would anyone second this procedure: http://www.centos.org/modules/newbb/viewtopic.php?topic_id=14052&forum=37&p… Thanks. Max Pyziur pyz(a)brama.com

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KVM with 6.2 i686 guest
by Jerry Geis 02 Jun '12

02 Jun '12

I just installed a KVM guest, centos 6.2 i686 (6.2 x86_64 host) and the network module is loaded . The modules is/are 8139too,8139cp is what lsmod shows. Dmesg shows link up but ifconfig does not give me an address? service network restart shows OK no errors but again no address. I set the ifcfg-eth0 file to not be NM controlled, onboot yes and rebooted. Same no address. I run 5.8 images all the time and they get the address? Did I forget something? Jerry

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Re: [CentOS] Add another one: the same sealert problem
by m.roth＠5-cent.us 01 Jun '12

01 Jun '12

Well, this is getting more and more unpleasant. Turned out my manager and the other admin were also working on this. One of the times they restarted *something*, or maybe my reinstall, took care of the first problem. Now, however, we're seeing a ton of exceptions... and what's struck me is that I'm *not* getting the normal output from sealert. For example, sealert -v -l 42f9d4f6-6327-4030-b927-d17ab9f4f0d6 2012-05-31 16:52:13,387 [plugin.INFO] importing /usr/share/setroubleshoot/plugins/__init__ as plugins SELinux is preventing /bin/chmod from using the fowner capability. I used the -v to try to get more; I'm not seeing the screenful that usually has more useful info. Could something have been screwed up with selinux, in some way? I know that the other admin installed something, but that was via a ruby-on-rails utility, and shouldn't have looked at anything, much less modified anything.... mark

2 1

issue with CentOS 6.2 autofs
by OVERBEY, DUDLEY 31 May '12

31 May '12

I have an issue with CentOS 6.2's autofs/automount. When I issue "service autofs start (or restart)" the automount daemon starts as expected, however, I am not able to access any of the exports nfs directories; but if I shutdown the automount daemon and start it by just issuing "/usr/sbin/automount", I am able to access all of the nfs directories. If the system reboots, the nfs directories become no longer available until I stop the automount daemon and restart by issuing "/usr/sbin/automount". Any assistance would be greatly appreciated. doverbey(a)optonline.net

2 1

portmap/NIS mystery
by Boris Epstein 31 May '12

31 May '12

Hello all, I have a server on my private network that is configured as an NIS server and mapped to a "public" IP address on a firewall. All other TCP ports (SSH, iperf, you name it) are visible from the outside - but the portmapper-managed ports (port 111 itself and the YPSERV/YPXFRD ports, etc.) are not visible from the outside - even though they are alive and well on the internal network. So, here's the question: is there anything special as far as portmapper's networking/security setup that is at play here? Thanks. Boris.

3 4

Re: [CentOS] Upgrading FC2 to CentOS 5.* - anyone second this?
by Les Mikesell 31 May '12

31 May '12

On Wed, May 30, 2012 at 2:54 PM, Reindl Harald <h.reindl(a)thelounge.net> wrote: > > i will not buy the argument with the hardware because > i had in the last years 4 notebooks, 3 workstations > and two different notebooks of my co-developer which > all done many dist-upgrades well if you know how > to prepare and cleanup What does 'last years' mean in kernels? New kernels have gotten better. A google for "FC5 kernel Oops' has 'about 334,000 results', so I'm not the only one. -- Les Mikesell lesmikesell(a)gmail.com

1 0

question for those who run mail servers
by Bob Hoffman 31 May '12

31 May '12

Not technically a centos question, but a lot of you guys seem to manage some large systems and I could use some clarification on a postfix setting.* *reject_unknown_client_hostname (in postfix < 2.3 reject_unknown_client) When I first used this there were issues with users trying to send mail through the server from hotels, wireless spots, etc. This was solved by pushing up permit sasl_authenticated. I took it out after those issues. I read many online posts from 2008 saying too many false positives. (though none were clear if those were incoming mail or from mail users) Do you use reject_unknown_client_hostname? Other than someone trying to access the server to send mail through it as a user I do not see how this could be a bad setting and am thinking of using it. A person sending out a mail to the server, even if in that badly set up hotel wireless should be using their gmail, yahoo, own server, isp mail servers and should not be directly sending from their iphone....is that correct? or do you ignore the use of this setting still? -thanks for any updates on the use of this setting.

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Discuss May 2012