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iptables
by mattias 26 Apr '11

26 Apr '11

Can anyone see any errors in this scripts Iptables says Invalid target iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE iptables -A FORWARD -i eth0 -o virbr0 -m state --state RELATED,ESTABLISHED -j ACCEPT iptables -A FORWARD -i virbr0 -o eth0 -j ACCEPT

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CentOS 5.6 x86_64 hosting unreachable Virtualbox 4.0.6 bridged guests
by Philippe 26 Apr '11

26 Apr '11

Hi, On a box running CentOS 5.6 x86_64 and Virtualbox 4.0.6, I have configured 2 guests (WinXP x86 + CentOS 5.6 x86_64) in bridged mode. The hosting box and the two guests are dhcp enabled. The hosting box get its address normally, but the 2 hosted systems fail to get theirs. The dhcp server log tells : DHCPDISCOVER from 08:00:xx:xx:xx:xx via em0: network xx.xx/16: no free leases. When changing from dhcp to static ip in the CentOS guest, 'service network restart' does not report any errors, but the guest keeps unreachable from the outside : pinging the guest works some times, but trying to reach the guest with ssh, http, or ftp always fail, with or whitout iptables enabled on the host and/or the guests. Please note that: - Kernel and softwares on the hosting CentOS are up-to-date, the box has an Intel Corporation 82567LM-3 Gigabit Network Connection (rev 02) NIC, does not have an Intel VT compliant CPU (Pentium E5700), but VT/AMD-V enabled in bios. - The host is not configured in bridged mode (does not have a br interface configured), Oracle telling that bridged mode on the host is not required to run Virtualbox guests in bridged mode. - The 2 guests work perfectly in NAT mode, but this mode is not an option for me. - The same 2 guests work perfectly in bridged mode on another same hosting box running Fedora 14. Is anyone experimenting the same difficulties with Virtualbox on CentOS 5.6 ? I don't know where to search to solve this problem. Thanks for your help ! -- Philippe

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random roundoff?
by Michael D. Berger 26 Apr '11

26 Apr '11

On my CentOS 5 box, in a C++ program that does much arithmetic, including numerous matrix multiplications, I have a situation in in which the result depends on the nature of nearby I/O. Thus, with all arithmetic done with type double, and where values are mostly in the range [-1.0e0,+1.0e0] or nearby, I do: cerr << "some stuff" << endl; mat3 = matmult(mat1,mat2); I get a difference of the order 1.0e-15 depending on whether the cerr line does or does not end in "endl" as shown. I am imagining that there is some "randomness" in the roundoff that depends on the I/O situation. Is this credible? Any other suggestions? Thanks for your help, Mike.

3 2

mdraid woes (missing superblock?)
by Jussi Hirvi 26 Apr '11

26 Apr '11

I have a raid1 array which is somehow faulty. There is 1,5 TB of stuff, I would not want to lose it (though I have full backup). The array cannot be mounted on startup (error message was "missing superblock"). I had to boot from DVD with linux rescue and remove the array from fstab. Here is some info - I am a little dumbfounded. [root@a134-224 log]# cat /proc/mdstat (...) md5 : active raid1 sdb1[0] sdd1[1] 1562505856 blocks [2/2] [UU] ## mdadm examine - I believe the following output indicates that there really *is* a superblock [root@a134-224 log]# mdadm --examine /dev/sdb1 /dev/sdb1: Magic : a92b4efc Version : 0.90.00 UUID : 194e7fdc:2a288e87:c03d8b24:c0120803 Creation Time : Sat Apr 23 20:41:08 2011 Raid Level : raid1 Used Dev Size : 1562505856 (1490.12 GiB 1600.01 GB) Array Size : 1562505856 (1490.12 GiB 1600.01 GB) Raid Devices : 2 Total Devices : 2 Preferred Minor : 5 Update Time : Tue Apr 26 11:48:35 2011 State : clean Active Devices : 2 Working Devices : 2 Failed Devices : 0 Spare Devices : 0 Checksum : 657d7a24 - correct Events : 14 Number Major Minor RaidDevice State this 0 8 17 0 active sync /dev/sdb1 0 0 8 17 0 active sync /dev/sdb1 1 1 8 49 1 active sync /dev/sdd1 # examine the other partition/dev/sdd1: Magic : a92b4efc Version : 0.90.00 UUID : 194e7fdc:2a288e87:c03d8b24:c0120803 Creation Time : Sat Apr 23 20:41:08 2011 Raid Level : raid1 Used Dev Size : 1562505856 (1490.12 GiB 1600.01 GB) Array Size : 1562505856 (1490.12 GiB 1600.01 GB) Raid Devices : 2 Total Devices : 2 Preferred Minor : 5 Update Time : Tue Apr 26 11:48:35 2011 State : clean Active Devices : 2 Working Devices : 2 Failed Devices : 0 Spare Devices : 0 Checksum : 657d7a46 - correct Events : 14 Number Major Minor RaidDevice State this 1 8 49 1 active sync /dev/sdd1 0 0 8 17 0 active sync /dev/sdb1 1 1 8 49 1 active sync /dev/sdd1 [root@a134-224 log]# mdadm --examine --scan (...) ARRAY /dev/md5 level=raid1 num-devices=2 UUID=194e7fdc:2a288e87:c03d8b24:c0120803 [root@a134-224 log]# mdadm --stop /dev/md5 mdadm: stopped /dev/md5 [root@a134-224 log]# mdadm --assemble /dev/md5 mdadm: /dev/md5 has been started with 2 drives. # but it cannot be mounted: [root@a134-224 log]# mount /dev/md5 /kvbck/ mount: you must specify the filesystem type [root@a134-224 log]# mount -t ext3 /dev/md5 /kvbck/ mount: wrong fs type, bad option, bad superblock on /dev/md5, missing codepage or other error In some cases useful info is found in syslog - try dmesg | tail or so [root@a134-224 log]# tail /var/log/messages Apr 26 17:14:09 localhost kernel: md: unbind<sdb1> Apr 26 17:14:09 localhost kernel: md: export_rdev(sdb1) Apr 26 17:14:09 localhost kernel: md: unbind<sdd1> Apr 26 17:14:09 localhost kernel: md: export_rdev(sdd1) Apr 26 17:14:17 localhost kernel: md: md5 stopped. Apr 26 17:14:17 localhost kernel: md: bind<sdd1> Apr 26 17:14:17 localhost kernel: md: bind<sdb1> Apr 26 17:14:17 localhost kernel: raid1: raid set md5 active with 2 out of 2 mirrors Apr 26 17:14:56 localhost kernel: hfs: unable to find HFS+ superblock Apr 26 17:15:05 localhost kernel: VFS: Can't find ext3 filesystem on dev md5. # Why does the log complain about HFS+ superblock? The fs should be ext3. - Jussi -- Jussi Hirvi * Green Spot Suvilahdenkatu 1 B 78 * 00500 Helsinki * Finland Tel. +358 9 493 981 * Mobile +358 40 771 2098 (only sms) jussi.hirvi(a)greenspot.fi * http://www.greenspot.fi

1 0

FYI - pci_mmcfg_init kernel error after upgrading to 5.6
by Windsor Dave L. (AdP/TEF7.1) 26 Apr '11

26 Apr '11

Just thought I'd pass along an error I received this weekend after upgrading two servers to 5.6. Both are HP Proliant DL380 servers running 64-bit, but one is a G6 model and one is a G7. After the upgrade and the reboot to the 2.6.18-238.9.1.el5 kernel, both servers displayed the following error at boot: "pci_mmcfg_init marking 256MB space uncacheable." Some Googling found me the following link: https://partner-bugzilla.redhat.com/show_bug.cgi?id=581933 There are apparently performance implications due to this issue. Fortunately, the solution is simple: just boot with the kernel parameter acpi_mcfg_max_pci_bus_num=on If everyone is already familiar with this, please ignore. :-) -- Best Regards, Dave Windsor Robert Bosch LLC Team Leader, MES Database Infrastructure Group (AdP/TEF7.1) 4421 Highway 81 North Anderson, SC 29621 USA www.bosch.us Tel: 1 (864) 260-8459 Fax: 1 (864) 260-8422 Dave.Windsor(a)us.bosch.com

4 8

updating libvorbis
by Philippe Naudin 26 Apr '11

26 Apr '11

Hello, On a machine with CentOS-5.6, I need libvorbis >= 1.2, so I have recompiled and packaged libvorbis. But I get the following error : $ rpm -U /usr/src/redhat/RPMS/x86_64/libvorbis-1.2.3-phn.1.x86_64.rpm /usr/src/redhat/RPMS/x86_64/libvorbis-devel-1.2.3-phn.1.x86_64.rpm package libvorbis-1.1.2-3.el5_4.4.x86_64 (which is newer than libvorbis-1.2.3-phn.1.x86_64) is already installed package libvorbis-devel-1.1.2-3.el5_4.4.x86_64 (which is newer than libvorbis-devel-1.2.3-phn.1.x86_64) is already installed Who knows how to make rpm understand than 1.2.3 is newer than 1.1.2 ? I have tried : %define name libvorbis Name: %{name} Provides: %{name} = %{version}-%{release} Obsoletes: %{name} < %{version}-%{release} and the same thing for %{name}-devel, but without any success. "Yum update" also fails, with the following error : Examining /usr/src/redhat/RPMS/x86_64/libvorbis-1.2.3-phn.1.x86_64.rpm: libvorbis-1.2.3-phn.1.x86_64 /usr/src/redhat/RPMS/x86_64/libvorbis-1.2.3-phn.1.x86_64.rpm: does not update installed package. Examining /usr/src/redhat/RPMS/x86_64/libvorbis-devel-1.2.3-phn.1.x86_64.rpm: libvorbis-devel-1.2.3-phn.1.x86_64 /usr/src/redhat/RPMS/x86_64/libvorbis-devel-1.2.3-phn.1.x86_64.rpm: does not update installed package. No Packages marked for Update Can someone help me ? Thanks, -- Philippe

2 4

opreport version 0.9.4 on Centos Linux 5.5
by Frank Chang 26 Apr '11

26 Apr '11

Nicholas Thierry-Mieg, Thank you for your reply on Saturday Apr 23,2011. Since then I have been trying to learn how to use oprofile 0.9.4 on Centos Linux 5.5. If I follow the following steps running as root, opcontrol --shutdown opcontrol --callgraph=7 opcontrol --image=/home/frankc/DQTTest5/MatchUpTest/lirh5g_deb/Mary48.exe opcontrol --start /home/frankc/DQTTest5/MatchUpTest/lirh5g_deb/Mary48.exe opcontrol --dump opreport -c > profile_info.txt or opreport -l /home/frankc/DQTTest5/MatchUpLib/lirh5g_deb/libmdMatchup.so I obtain the following warning: warning: the last modified time of the binary file does not match that of the sample file for /home/frankc/DQTTest5/MatchUpLib/lirh5g_deb/libmdMatchup.so Either this is the wrong binary or the binary has been modified since the sample file was created. warning: the last modified time of the binary file does not match that of the sample file for /home/frankc/DQTTest5/MatchUpTest/lirh5g_deb/MatchUpAccurate.exe I am wondering how to prevent this warning message from occuring because it indicates our profiling results may be incorrect. Thank you.

1 0

Adding comments to /etc/sysconfig/iptables
by Alexander Farber 26 Apr '11

26 Apr '11

Hello, I'm a user (and big fan) of CentOS 5.6 and in my /etc/sysconfig/iptables there are few blocking rules for some annoying visitors of my website (I run a card game there since many years and some people are "special"): *filter :INPUT DROP [0:0] :FORWARD DROP [0:0] :OUTPUT ACCEPT [294:35064] -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT -A INPUT -i lo -j ACCEPT -A INPUT -s xx.xx.xx.0/24 -j DROP -A INPUT -s xx.xx.xx.0/24 -j DROP -A INPUT -s xx.xx.xx.0/24 -j DROP -A INPUT -s xx.xx.xx.0/24 -j DROP -A INPUT -s xx.xx.xx.0/24 -j DROP -A INPUT -s xx.xx.0.0/16 -j DROP -A INPUT -p icmp -m icmp --icmp-type any -j ACCEPT -A INPUT -p tcp -m state --state NEW -m tcp -m multiport --dports 80,8080,443 -j ACCEPT -A INPUT -p tcp -m state --state NEW -m tcp --dport 22 \ --tcp-flags FIN,SYN,RST,ACK SYN -m limit --limit 1/min --limit-burst 2 -j ACCEPT COMMIT My problem is that I often don't remember why and when a blocking rule had been added. Is there a way to add comments to the iptables file? A hash mark # does not seem to work. If comments not possible, please share few tricks - how do YOU usually use iptables on CentOS, i.e. there is "sudo service iptables save", but I've yet to discover its usefulness Regards Alex

5 5

Blocking an IP address both as source and destination
by Alexander Farber 25 Apr '11

25 Apr '11

Hello, how do you block incoming AND outgoing traffic to a site? I have 2 drop lines for a site in my /etc/sysconfig/iptables: *filter :INPUT DROP [0:0] :FORWARD DROP [0:0] :OUTPUT ACCEPT [294:35064] -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT -A INPUT -i lo -j ACCEPT -A INPUT -s xx.xx.xx.0/24 -j DROP -A INPUT -d xx.xx.xx.0/24 -j DROP -A INPUT -p icmp -m icmp --icmp-type any -j ACCEPT -A INPUT -p tcp -m state --state NEW -m tcp -m multiport --dports 80,8080 -j ACCEPT -A INPUT -p tcp -m state --state NEW -m tcp --dport 22 --tcp-flags FIN,SYN,RST,ACK SYN -m limit --limit 1/min --limit-burst 2 -j ACCEPT COMMIT but for some reason still can "ping xx.xx.xx.1" and "ssh xx.xx.xx.1" prints "ssh: connect to host xx.xx.xx.1 port 22: Connection refused" immediately, which probably means my packets aren't dropped at all. Using CentOS 5.6/64 bit Thank you Alex

4 5

centosplus kernel not up to date ?
by Nicolas Ross 25 Apr '11

25 Apr '11

Is it possible that the kernel in the centosplus repo is not up to date ? The centosplus kernel I have is kernel-PAE-2.6.18-238.5.1.el5 and the regular one is 2.6.18-238.9.1.el5... I need the plus because of the firewire drivers. Regards,

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