Discuss February 2012

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205 participants
194 discussions

OFF TOPIC. The best course of CentOS in USA
by Edson - PMSS 19 Feb '12

19 Feb '12

I would like to know which all of you point me as the best training course of CentOS in the world or in the USA. I am a Brazilian and I would like to have this information. I have a good background in GNU/Linux, CentOS and Debian like operating systems, network and general knowledge. I would like to know a deep course about all this subject. I would appreciate any kind of information in advance. Thanks all! -- Edson D. Amaral --------------- Listen to the voices inside of you, they will tell you what is right and what is wrong, they will bring you happiness and peace; if you don't listen to them they can create anxiety, discontentment, and unhappiness. Ouça as vozes dentro de você, elas vão te dizer o que é certo e o que é errado, elas vão lhe trazer felicidade e paz, se você não ouví-las, elas poderão criar ansiedade, insatisfação e infelicidade. Bert Wilson The Five Secrets you must discover before you die, pg. 155

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Re: [CentOS] centos security
by Les Bell 19 Feb '12

19 Feb '12

Al <mailinglist(a)theflux.net> wrote: >> Any suggestions on what to run on a centos box to verify that the server isn't compromised or being sniffed? Thanks! << For "isn't compromised", you need a host integrity verification system like Tripwire or AIDE (which is in the base repo). Expect to have to tweak the config to cover the stuff you've got installed. You can detect sniffing by checking for promiscuous interfaces on the LAN - use proDETECT (http://sourceforge.net/projects/prodetect/) or a similar tool for this purpose. Alternatively, if you have the time and resources, you could run a full-blown network intrusion detection system like Snort (http://www.snort.org) Best, --- Les Bell [http://www.lesbell.com.au] Tel: +61 2 9451 1144

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Sound drop out with totem. mplayer Can't open audio device /dev/dsp
by Mark LaPierre 19 Feb '12

19 Feb '12

Hey all. This morning I found that my audio playback is randomly sprinkled with sound skips and dropouts. I went to /var/log/yum.log and found this: Feb 09 20:18:22 Updated: lame-3.99.4-2.el6.rf.i686 I'm not saying that caused the problem but it's all I could find that changed. When I ls in /dev there is no dsp entry. That would explain why mplayer Can't open audio device /dev/dsp. I don't know why there is no /dev/dsp. MPlayer 1.0rc4-4.4.6 aplay just makes a nasty hiss. aplay: version 1.0.21 I'm using pulesaudio $ rpm -qa | grep pulseaudio alsa-plugins-pulseaudio-1.0.21-3.el6.i686 pulseaudio-module-bluetooth-0.9.21-13.el6.i686 pulseaudio-0.9.21-13.el6.i686 pulseaudio-libs-0.9.21-13.el6.i686 pulseaudio-utils-0.9.21-13.el6.i686 pulseaudio-module-gconf-0.9.21-13.el6.i686 pulseaudio-module-x11-0.9.21-13.el6.i686 pulseaudio-gdm-hooks-0.9.21-13.el6.i686 pulseaudio-libs-glib2-0.9.21-13.el6.i686 $ uname -a Linux mushroom.patch 2.6.32-220.4.1.el6.i686 #1 SMP Mon Jan 23 22:37:12 GMT 2012 i686 i686 i386 GNU/Linux CentOS 6.2 Any of these may, or may not, be related. -- _ °v° /(_)\ ^ ^ Mark LaPierre Registerd Linux user No #267004

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Re: [CentOS] SPF Record questions
by Jonathan Vomacka 18 Feb '12

18 Feb '12

On 2/18/2012 12:53 PM, Reindl Harald wrote: > > > Am 18.02.2012 18:33, schrieb Jonathan Vomacka: >>>>> -all will cause some MTA's to reject >>> >>> then they are badly broken >>> >>>>> ~all is better to use >>> >>> this means SPF is in testing mode and not enforced >>> some servers may use them for scoring but they will >>> never be used for blocking spoofed messages from >>> wrong sender-addresses >>> _____________________ >>> >>> however, below are SPF-compliant records working since >>> years for some hundret domains, maybe your BIND-version >>> does not support record-type "SPF" (Recent Fedora does) >>> >>> RFC says a SPF-compliant domain should use both >>> >>> and yes i prefer ip4 instead A/MX because this is enforcing >>> a lower count of dns requests at all and our internal dns >>> baclend is able to translate configured hostnames to IP >>> while generating the zone-files from the database >>> _____________________ >>> >>> @ IN TXT "v=spf1 ip4:91.118.73.15 ip4:91.118.73.20 -all" >>> @ IN SPF "v=spf1 ip4:91.118.73.15 ip4:91.118.73.20 -all" >>> >>> subdomain1 IN TXT "v=spf1 ip4:91.118.73.15 ip4:91.118.73.20 -all" >>> subdomain1 IN SPF "v=spf1 ip4:91.118.73.15 ip4:91.118.73.20 -all" >>> >> >> Reindl, >> >> What about if someone uses a mobile device to send e-mail? > > what is the difference between a mobile device and a customer > at home on his workstation? there is no one! bot have to use > the SMTP for their account > >> Would ~all be better? > > it is making less trouble for people using their ISP-MTA > but this people are acting wrong and if you want to enforce > SPF they must not do this, if you want life easy for people > who acting wrong you CAN NOT enforce SPF at all > >> I also generated the following SPF >> using a wizard. Let me know if this looks correct: >> >> teamwarfare.com. IN TXT "v=spf1 a mx a:mail.teamwarfare.com a:mail2.teamwarfare.com ip4:66.90.73.80 >> ip4:216.250.250.148 ~all" > > looks OK, without enforcing > > i made the expierience in the last years that A/MX in SPF makes > often troubles since there are more dns-requestes need on the > receiver and this is raised up with every entry of these types > in your SPF - ip4 does not need additional requests > > they often produced false positives, never seen again since changed to ip4 > >> I wouldn't need an "include:" or "ptr" statement in this right? I would told "include:" was to include OTHER >> domains that are allowed to send e-mail, but then again I see some people writing the domain again as an include. >> Also is PTR good to use or not? > > no idea > > i am using strictly ip4-entries and do not mixing domains > all users are instructed to use "mail.ourdomain.tld" and > there are not existing dns-records in customer domains as > also all MX-records of them are poining FQ to our spam-firewall > Reindl, I am sorry to ask this, but is it possible you can modify my PTR record that I submitted above with how you would enter it into BIND? I want to make sure I accurately enter this.

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Bind DNS SPF Record
by Jonathan Vomacka 18 Feb '12

18 Feb '12

I know this is a bit off topic from CentOS itself, but are there any DNS experts that would be able to e-mail me on the side and assist with some questions I have regarding TXT/SPF records? I want to ensure my mail doesn't bounce.

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Re: [CentOS] SPF Record questions
by Jonathan Vomacka 18 Feb '12

18 Feb '12

On 2/18/2012 12:05 PM, Reindl Harald wrote: > > > Am 18.02.2012 17:53, schrieb Jonathan Vomacka: >> I am inquiring about how to setup a proper SPF record. I know there are >> SPF wizards/generators available but each seem to have a different >> "opinion" of what should be included and what should not be included. >> >> Let me give you a scenario of my setup, and hopefully someone can help >> me out. >> >> My domain is: test.com >> My mailserver hostname is: mail.host.com which also has a MATCHING PTR >> record >> mail.host.com (for example) resolves to 50.1.1.1 and 50.1.1.1 resolves >> to mail.host.com >> >> This is a STANDALONE mail server which will receive and send email >> without any VIP's or load balancing. There is however one additional >> host that will send out mail from the domain but it wont be receiving >> mail, it will only be used as an SMTP (outbound only) server attached to >> a website automailer which is on a seperate webserver... It only >> generates error reports and sends them out... so technically it isn't a >> full mail server but it will be sending (outbound only) mail on behalf >> of the domain. >> >> The additional host is: mail2.test.com which resolves to 50.2.2.2 and >> there is a Matching PTR. >> >> These are the ONLY mail servers and IP addresses that will be sending >> out mail from the test.com domain. Some websites say I should use -all >> and others say -all will cause some MTA's to reject and ~all is better >> to use even if those are the only two hosts sending out mail. >> >> Would you be able to assist with a solid SPF record? > >>> -all will cause some MTA's to reject > > then they are badly broken > >>> ~all is better to use > > this means SPF is in testing mode and not enforced > some servers may use them for scoring but they will > never be used for blocking spoofed messages from > wrong sender-addresses > _____________________ > > however, below are SPF-compliant records working since > years for some hundret domains, maybe your BIND-version > does not support record-type "SPF" (Recent Fedora does) > > RFC says a SPF-compliant domain should use both > > and yes i prefer ip4 instead A/MX because this is enforcing > a lower count of dns requests at all and our internal dns > baclend is able to translate configured hostnames to IP > while generating the zone-files from the database > _____________________ > > @ IN TXT "v=spf1 ip4:91.118.73.15 ip4:91.118.73.20 -all" > @ IN SPF "v=spf1 ip4:91.118.73.15 ip4:91.118.73.20 -all" > > subdomain1 IN TXT "v=spf1 ip4:91.118.73.15 ip4:91.118.73.20 -all" > subdomain1 IN SPF "v=spf1 ip4:91.118.73.15 ip4:91.118.73.20 -all" > > > Reindl, What about if someone uses a mobile device to send e-mail? Would ~all be better? I also generated the following SPF using a wizard. Let me know if this looks correct: teamwarfare.com. IN TXT "v=spf1 a mx a:mail.teamwarfare.com a:mail2.teamwarfare.com ip4:66.90.73.80 ip4:216.250.250.148 ~all" I wouldn't need an "include:" or "ptr" statement in this right? I would told "include:" was to include OTHER domains that are allowed to send e-mail, but then again I see some people writing the domain again as an include. Also is PTR good to use or not?

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SPF Record questions
by Jonathan Vomacka 18 Feb '12

18 Feb '12

I am inquiring about how to setup a proper SPF record. I know there are SPF wizards/generators available but each seem to have a different "opinion" of what should be included and what should not be included. Let me give you a scenario of my setup, and hopefully someone can help me out. My domain is: test.com My mailserver hostname is: mail.host.com which also has a MATCHING PTR record mail.host.com (for example) resolves to 50.1.1.1 and 50.1.1.1 resolves to mail.host.com This is a STANDALONE mail server which will receive and send email without any VIP's or load balancing. There is however one additional host that will send out mail from the domain but it wont be receiving mail, it will only be used as an SMTP (outbound only) server attached to a website automailer which is on a seperate webserver... It only generates error reports and sends them out... so technically it isn't a full mail server but it will be sending (outbound only) mail on behalf of the domain. The additional host is: mail2.test.com which resolves to 50.2.2.2 and there is a Matching PTR. These are the ONLY mail servers and IP addresses that will be sending out mail from the test.com domain. Some websites say I should use -all and others say -all will cause some MTA's to reject and ~all is better to use even if those are the only two hosts sending out mail. Would you be able to assist with a solid SPF record?

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CentOS4 desktop has stopped recognizing removable media - haldaemon problem?
by Bart Schaefer 18 Feb '12

18 Feb '12

USB sticks and cameras used to pop right up on my desktop. Now they don't. I've checked the Gnome "Drives and Media Preferences" and nothing has changed -- I have "Mount removable media when inserted" etc. (Tried toggling it off and back on, no effect.) I've logged out and back in, even rebooted. /var/log/messages shows the devices are being recognized by udev: Jun 27 19:53:37 torch kernel: Attached scsi removable disk sde at scsi11, channel 0, id 0, lun 0 Jun 27 19:53:37 torch scsi.agent[13576]: disk at /devices/pci0000:00/0000:00:0b.1/usb1/1-5/1-5:1.0/host11/target11:0:0/11:0:0:0 Jun 27 19:53:37 torch udevd[1347]: udev done! Jun 27 19:53:47 torch udevd[1347]: udev done! However, that's followed by this: Jun 27 19:54:07 torch hald[5179]: Timed out waiting for hotplug event 699. Rebasing to 699 I restarted hald (service haldaemon restart) and it picked up one of the two devices I'd plugged in, but not the other.

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smartd and smartctl
by m.roth＠5-cent.us 17 Feb '12

17 Feb '12

A few weeks ago, one of my servers started complaining, via smartd, that one drive had one unreadable sector. I umounted it, and ran an fsck -c, then remounted it. Error didn't go away. Now, what's really annoying is that I've gotten back to it today, and it's reporting the problem, as it has for weeks now, every half an hour. However, when I run > smartctl -q errorsonly -H -l selftest -l error /dev/sdb it gives me *nothing*. Anyone understand why I get two different results? mark "and I am waiting for the smartctl -t long /dev/sdb to complete"

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yum update stuck...
by John Doe 17 Feb '12

17 Feb '12

Hi, Running Transaction Updating : selinux-policy 1/6 Updating : kmod-r8168 2/6 Working. This may take some time ... An hour later, still working... S+ 10:51 0:08 | \_ /usr/bin/python /usr/bin/yum update S+ 10:53 0:00 | \_ /bin/sh /var/tmp/rpm-tmp.9003 2 S+ 10:53 0:00 | \_ /bin/bash /sbin/weak-modules --add-modules S+ 10:53 0:00 | \_ /bin/bash --norc /sbin/mkinitrd --allow-missing -f /boot/initrd-2.6.18-274.17.1.el5.tmp 2.6.18-274.17.1.el5 S+ 10:53 0:00 | \_ /bin/bash --norc /sbin/mkinitrd --allow-missing -f /boot/initrd-2.6.18-274.17.1.el5.tmp 2.6.18-274.17.1.el5 D+ 10:53 0:00 | \_ lvm.static lvs --ignorelockingfailure --noheadings -o vg_name /dev/md1 I tried an strace but nothing shows up. Now, it is in: T+and strace showed me it was/is stuck on "phantom" usb devices and doing lvm stuff while I do not use lvm... Should I wait or can I just ctrl-c, reset the usb_storage module to clean up and retry yum update? Thx, JD

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Discuss February 2012