Discuss April 2011

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312 participants
282 discussions

OFFTOPIC :: IB hardware choice
by Adrian Sevcenco 06 Apr '11

06 Apr '11

Hi! I would need an advice from those that use IB (as admins :) ) i have a choice between : 1. Mellanox InfiniHost® III Lx HCA card, single-port CX4, DDR, PCIe x8, mem-free, tall bracket, RoHS R5 2. QLogic Single Port 20 Gb InfiniBand to x16 PCI Express Adapter (Single Pack) aside the price is there anything else that could help me make a discrimination between this two? (these will be used in twin servers for a small (up to 24 nodes) parallel cluster) Thanks! Adrian

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Re: [CentOS] Centos 6 Update?
by Ian Murray 06 Apr '11

06 Apr '11

> Thats a very good question, and something more people should be asking > : here is a terse reply : adopt a part of the distro, contribute tests > and take ownership of driving support for those components forward ( so, > wiki content, support in irc channels and support for users on those > components in the mailing lists ). Start with a package or two, then > move that forward. Start with whats already in the distro. > > Its easy to fixate on the idea of CentOS being the distro and the distro > alone - however, a very large part of what the users see value in is the > user base around CentOS - and focused, specialised help with those areas > would go a long way in 'helping' CentOS. Would this help get a future release out of the door quicker?

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Re: [CentOS] KILL THIS THREAD ( Centos 6 Update?)
by Ian Murray 06 Apr '11

06 Apr '11

----- Original Message ----- > From:Kai Schaetzl <maillists(a)conactive.com> > > > This thread or others like it will continue > > wrong. It will continue as long people bite. Stop biting the bait! > > Kai Oh, the irony.... Likewise. Somebody will still keep coming onto ask the questions, esp. non-regular list users.... hell, people do it now and the subject has been done to death over the last few months. I personally see little point in the threads either. As far as I can tell, you have to accept the situation as-is or switch distro. Dev model isn't going to change and previously said, anyway... maybe the rebuild model for non-hobbyist use has run its course.

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sshd: Authentication Failures: 137 Time(s)
by Rainer Traut 06 Apr '11

06 Apr '11

Hi, to prevent scripted dictionary attacks to sshd I applied those iptables rules: -A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -m recent --update --seconds 60 --hitcount 4 --name SSH --rsource -j DROP -A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -m recent --set --name SSH --rsource And this is part of logwatch: sshd: Authentication Failures: unknown (www.telkom.co.ke): 137 Time(s) unknown (mkongwe.jambo.co.ke): 130 Time(s) unknown (212.49.70.24): 107 Time(s) root (195.191.250.101): 8 Time(s) How is it possible for an attacker to try to logon more then 4 times? Can the attacker do this with only one TCP/IP connection without establishing a new one? Or have the scripts been adapted to this? Thx Rainer

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Forcing IPv4 DNS lookups first before IPv6
by Russell Jones 06 Apr '11

06 Apr '11

Hello! I am having a strange issue with CentOS 5.4 that I cannot seem to solve. Every DNS lookup results in AAAA records being requested first before A records. As a result, this causes a large amount of unnecessary DNS traffic on the network. IPv6 has been completely disabled on these servers: /etc/modprobe.conf, ipv6 off and net-pf-10 off /etc/sysconfig/network, NETWORKING_IPV6=no lsmod | grep ipv6 shows the kernel module no longer loaded. Yet watching TCP dump shows that AAAA records are requested before A records every time a login is requested from one of our local machines to another. Is there some sort of configuration directive I can use to force IPv4 lookups first before IPv6? Or even better, stop IPv6 lookups all together?

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Re: [CentOS] KILL THIS THREAD ( Centos 6 Update?)
by Ian Murray 06 Apr '11

06 Apr '11

----- Original Message ----- > From:Kai Schaetzl <maillists(a)conactive.com> > To:centos@centos.org > Cc: > Sent:Tuesday, 5 April 2011, 13:21 > Subject:Re: [CentOS] KILL THIS THREAD ( Centos 6 Update?) > > +100 !!!! > > Kai Anybody that thinks this thread can be "killed" is so badly mis-understanding the situation. This thread or others like it will continue to pop-up in the short term until all releases are in-line with RH and then they will continually re-appear with subsequent releases. So 'killing' the thread is akin to burying ones head in the sand. I question whether a rebuild project is a sensible way forward for anything but hobbyist use. That isn't a criticism of the dev team (before anyone tries to twist it as such) but more a question about the viability of the model.

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screen
by Agile Aspect 05 Apr '11

05 Apr '11

Hi - under CentOS 5, has anyone be able to get the vertically splitting under screen to work? I downloaded the latest screen-4.0.3 and the wrp_vertical_split_0.3_4.0.2.diff.bz2 patch for vertical splitting and I still can't get it work. ^A | doesn't do anything. Horizontal splitting works fine. -- Agile

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OT Problem seeing slave drives.
by Jimmy Bradley 05 Apr '11

05 Apr '11

This isn't specifically about cent os, but I am running cent os on this machine. I've got a Dell Dimension 2400 desktop pc. I've tried on a number of occasions to put a second hard drive in the machine, but I can't get the machine to recognize the second drive in BIOS. I'm going to try and keep this short and sweet. I've tried all that I know to try. I've set the jumpers on the drives to master and slave, I've tried setting the jumpers to cable select. I've changed the IDE ribbon cable. As far as I know, I've done all the trouble shooting steps that you'd do when having this problem. The only conclusion I can come up with, is that it's the BIOS. The one thing I haven't done is flash the BIOS, and I'm reluctant to do that. One other thing that I did try, was on the secondary IDE, I tried connecting a second CD drive, and the BIOS would not see it either. The machine will only see the drives that are connected to what would be the Master drive connection on the ribbon cable. Anyone have any ideas? Thanks Jim

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How to install wine ?
by Rajan Dahal 05 Apr '11

05 Apr '11

Hello friends, I have downloaded wine-1.3.13.tar.bz2 How to install it ? I have no internet connection. so I want to install it manually. Thanks in advance. Rajan

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Re: [CentOS] CentOS Digest, Vol 75, Issue 5
by Chuck Munro 05 Apr '11

05 Apr '11

On 04/05/2011 09:00 AM, John R Pierce wrote: > > AFAIK, no standard raid modes verify parity on reads, as this would > require reading the whole slice for every random read. Only raid > systems like ZFS that use block checksuming can verify data on reads. > parity (or mirrors) are verified by doing 'scrubs' > > Further, even if a raid DID verify parity/mirroring on reads, this would > at best create a nonrecoverable error (bad data on one of the N drives > in the slice, no way of knowing which one is the bad one). > Thanks John, that's good information, something I didn't know. So I should think of RAID-5/6 parity as a mechanism for recovering from a drive fault that is more space-efficient than simple mirroring. Maybe RAID-10 with hot spares is more than "good enough" in most applications, but I do like dual parity for its ability to recover even in the face of a disk error popping up during the rebuild. Am I being too paranoid? Too bad ZFS on Linux is still up at the fuse layer. I understand Btrfs is rolled into newer kernels and should be in CentOS-6, but I read somewhere it's not yet in stable release and has some potential issues, so I'm reluctant to try it. It won't have RAID-6-like parity for a while. The fact that Oracle has both ZFS and Btrfs under its wing is, um, "interesting". I'm only asking for the world :-) Chuck

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Discuss April 2011