Discuss October 2014

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199 participants
222 discussions

DHCP with ipv6 tunnel
by Ashley M. Kirchner 06 Oct '14

06 Oct '14

I'm completely confused here and I'm hoping someone here has a setup they're willing to share, or help me configure things on my end. My connectivity is through Comcast, who unfortunately, does not offer ipv6 in my area. My connection goes like this: Comcast -> Motorola Surfboard Cable Router -> CentOS 6.5 server The CentOS server is multi-homed and manages the internal 192.168.x.x network by offering DHCP and firewall service (NATting and others.) DNS lookups are going to Comcast's servers. I have an IPV6 tunnel through Hurricane Electric (www.tunnelbroker.net) The tunnel is configured and is up and running on the CentOS server. I can ping several IPV6 addresses from it just fine: ping6 -n ipv6.google.com PING ipv6.google.com(2607:f8b0:400f:801::1006) 56 data bytes 64 bytes from 2607:f8b0:400f:801::1006: icmp_seq=1 ttl=53 time=109 ms 64 bytes from 2607:f8b0:400f:801::1006: icmp_seq=2 ttl=53 time=109 ms 64 bytes from 2607:f8b0:400f:801::1006: icmp_seq=3 ttl=53 time=106 ms ^C --- ipv6.google.com ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 2436ms rtt min/avg/max/mdev = 106.905/108.723/109.756/1.317 ms What I'd like to do now is have DHCP offer ipv6 addresses as well. Problem is, I don't know how to configure it properly using the information given to me by Hurricane. I have my client address which is what the CentOS tunnel interface is. Then I have a routed /64 and /48 prefix which I *think* is what I'm supposed to use for my internal network (according to their info popup window) but I don't know how to configure DHCPd to use that and then route through the ipv6 interface. So does anyone here have a tunnel from HE and are using DHCP on an internal network handing out ipv6 addresses? Any suggestions of how to configure dhcpd6.conf? Thanks all. Ash

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About CentOS Storage SIG and RedHat Storage Server 3.0
by C. L. Martinez 06 Oct '14

06 Oct '14

Hi all, Does someone from CentOS Storage SIG can say something about this subject? Is it planned to accomplish some RHSS 3 rebuild for CentOS 6.5?? Thanks.

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Centos 7: Remove Gnome from GDM options
by Frank Cox 05 Oct '14

05 Oct '14

When you click on the gear icon on the GDM login screen, it provides a list of the available desktop environments so you can pick between them. Since I exclusively use Mate on this computer, how can I remove the other options from that menu? Earlier today when I logged in the machine decided on its own that what I really wanted was Gnome Classic, so I had to log out to change it back to Mate, then log in again. I would like to tell it to use Mate exclusively, with no other options to select by mistake. -- MELVILLE THEATRE ~ Real D 3D Digital Cinema ~ www.melvilletheatre.com

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lvcreate error
by Aaron Siegel 05 Oct '14

05 Oct '14

Hello I am unable create a new logical volume, I receive the following error when using lvcreate # lvcreate -L 1g -n system3_root hm device-mapper: resume ioctl on failed: Invalid argument Unable to resume hm-system3_root (253:7) Failed to activate new LV. # pvs PV VG Fmt Attr PSize PFree /dev/sda4 hm lvm2 a-- 998.00g 864.75g # gvs VG #PV #LV #SN Attr VSize VFree hm 1 6 0 wz--n- 998.00g 864.75g #lvs LV VG Attr LSize Pool Origin Data% Move Log Cpy% Sync Convert docker hm -wi-ao---- 15.00g libvirt-images hm -wi-ao---- 63.24g swap0 hm -wi-ao---- 30.00g system2_root hm -wi-ao---- 15.00g system2_var hm -wi-ao---- 5.00g system3_var hm -wi-a----- 5.00g

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CentOS 7 - Have 2 disks, each with a biosboot partition, can only boot off one of them
by Digimer 05 Oct '14

05 Oct '14

Hi all, I used a kickstart script to setup a new machine of mine with RAID 1 (I couldn't get anaconda to create matching partition schemes). So I've now got /dev/sdg1 and /dev/sdh1 as 'bios_grub' (/dev/sd{a-f} are a separate array). 0 root@an-nas02:~# parted /dev/sdg print free Model: ATA ST3000NC000 (scsi) Disk /dev/sdg: 3001GB Sector size (logical/physical): 512B/4096B Partition Table: gpt Disk Flags: pmbr_boot Number Start End Size File system Name Flags 17.4kB 1049kB 1031kB Free Space 1 1049kB 3146kB 2097kB bios_grub 2 3146kB 3001GB 3001GB raid 3001GB 3001GB 466kB Free Space 0 root@an-nas02:~# parted /dev/sdh print free Model: ATA ST3000NC000 (scsi) Disk /dev/sdh: 3001GB Sector size (logical/physical): 512B/4096B Partition Table: gpt Disk Flags: pmbr_boot Number Start End Size File system Name Flags 17.4kB 1049kB 1031kB Free Space 1 1049kB 3146kB 2097kB bios_grub 2 3146kB 3001GB 3001GB raid 3001GB 3001GB 466kB Free Space I can only boot off of /dev/sdh, so I tried to run 'grub2-install' against /dev/sdg and it failed with this error: *** Error in `grub2-install': double free or corruption (fasttop): 0x00000000010a83b0 *** (full error: http://fpaste.org/139382/25324161/) It seems like it's blowing up on grub2-probe, as I can generate the same error. I tried specifying the device: 0 root@an-nas02:~# df -hP |grep boot /dev/mapper/an--nas02_vg0-lv_boot 506M 133M 373M 27% /boot 0 root@an-nas02:~# lvdisplay /dev/an-nas02_vg0/lv_boot |grep VG VG Name an-nas02_vg0 0 root@an-nas02:~# pvdisplay /dev/md0 | grep -e "VG Name" -e "PV Name" PV Name /dev/md0 VG Name an-nas02_vg0 0 root@an-nas02:~# cat /proc/mdstat |grep md0 md0 : active raid1 sdg2[1] sdh2[0] 0 root@an-nas02:~# ls -lah /dev/mapper/an--nas02_vg0-lv_boot lrwxrwxrwx. 1 root root 7 Oct 5 18:45 /dev/mapper/an--nas02_vg0-lv_boot -> ../dm-2 0 root@an-nas02:~# ls -lah /dev/dm-2 brw-rw----. 1 root disk 253, 2 Oct 5 18:45 /dev/dm-2 0 root@an-nas02:~# grub2-probe -d /dev/dm-2 *** Error in `grub2-probe': double free or corruption (fasttop): 0x0000000001e9cfd0 *** ======= Backtrace: ========= /lib64/libc.so.6(+0x7d1ad)[0x7f9c702da1ad] <snip> Full error: http://fpaste.org/139387/41253399/ So I am wondering how I can make /dev/sdg bootable? A RAID 1 array is of limited use if I can only boot off of one of the disks. :) Thanks! -- Digimer Papers and Projects: https://alteeve.ca/w/ What if the cure for cancer is trapped in the mind of a person without access to education?

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VMWare Workstation Guest Keep Crashing
by Igal ＠ getRailo.org 05 Oct '14

05 Oct '14

hi all, I've inherited a CentOS 6.4 machine that runs VMWare Workstation 9 which in turn hosts a Windows SBS 2011 guest. the problem is that the Windows guest keeps crashing, and I have no idea why. it was working fine for a while but recently started crashing after a day or two of operation. as a total Linux/CentOS noob, I have some questions: 1) is it safe to assume that since the guest crashes, but not the host, then the issue is with the Windows setup and not the CentOS? 2) any ideas how I would go to find the problem? 3) I understand now that a better virtualization would be KVM or Xen. any word of advice on which is better if the host machine need only run the guest OS and back it up? TIA! -- Igal Sapir Railo Core Developer http://getRailo.org/

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Re: [CentOS] [exim] how to check a message header for being empty
by Always Learning 05 Oct '14

05 Oct '14

On Sun, 2014-10-05 at 12:51 +0100, Dennis Davis wrote: > On Sat, 4 Oct 2014, lee wrote: > > > Is the Subject: header required by some RFC? If it is, I'll also > > deny messages that don't have one. > Not as far as I'm aware. RFC5322, "Internet Message Format", > contains: > > The only required header fields are the origination date field and > the originator address field(s). All other header fields are > syntactically optional. More information is contained in the table > following this definition. There is a real difference between the lack of a Subject: header and a present but empty Subject: header. I reject emails with no Subject: headers but accept empty Subject: headers because even I can occasionally forget to type-in a Subject. -- Regards, Paul. England, EU.

1 0

Respective Roles of NetworkManager.service and Network.service
by Richer, Mark (CIV) 05 Oct '14

05 Oct '14

I know folks have different opinions about Network Manager, but while researching how to change the name of a NIC without rebooting, I also came across the following page from RedHat that I’ll share as I find it’s very clear and concise explanations on how these services interact on CentOS/RHEL 7: https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/ht… It answered my question as to whether it’s appropriate to have both services running and apparently this is fine, but not necessary depending on how you configure networking. Mark MARK H RICHER, MS CS NPS-NCR Digital Forensics Lab IT Manager Computer Science Department Naval Postgraduate School - National Capital Region (NCR) 900 N Glebe Rd, Rm 5-182, Arlington, VA 22203 571.858.3254 (o) 571.303.9498 (m) mhricher(a)nps.edu<mailto:mhricher@nps.edu>

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how2 mount ntfs partition that is part of a full HD image file
by Fred Smith 05 Oct '14

05 Oct '14

I have a full disk image file (courtesy of ddrescue), and need to mount one of its partitions. I suppose I should have just extracted the single partition when I was using ddrescue, but right now I have the whole disk instead, and no disk space left to re-do the extraction (in fact I won't be able to use the system where I did it for several weeks, so I'd love to be able to mount just the partition from the image I have). I'll be doing some digging, but thought I'd inquire here too. thanks in advance! -- ------------------------------------------------------------------------------- Under no circumstances will I ever purchase anything offered to me as the result of an unsolicited e-mail message. Nor will I forward chain letters, petitions, mass mailings, or virus warnings to large numbers of others. This is my contribution to the survival of the online community. --Roger Ebert, December, 1996 ----------------------------- The Boulder Pledge -----------------------------

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Mounting LUNs from a SAN array - LUN mappings to devices in /dev/ - are they static?
by Rafał Radecki 04 Oct '14

04 Oct '14

Hi All :) I am currently involved in a project in which there is a SAN array (Sun Storagetek 2540) which exports LUNs for some servers with Centos 5.2 x86. I will be performing a migration to Centos 5.9 x86_64 in some time and am gathering needed info now :) I am trying to find the place in the OS where there is the information about LUN mappings to /dev/ devices. For example on array level I have an exported LUN with number 8. I see it on one of the servers with lsscsi as: # lsscsi | grep '7\:0\:0\:8' [7:0:0:8] disk SUN LCSM100_F 0735 /dev/sdj As I said I need to perform migration of the OS to Centos 5.9 x86_64 and am curious where from does the mapping scsi device 7:0:0:8 <-> /dev/sdj come? I have some complex logical volume (Veritas Volume Manager) setup based on /dev/ disks (which are derived from LUNs imported from the array) and will need to recreate it on destination servers. My coworker said that udev may be assigning the /dev/sdj (and other) identifier so I checked this. In /etc/udev/rules.d/* I see rules for scsi subsystem (sysfs type 0 is "disk"): ACTION=="add", SUBSYSTEM=="scsi", WAIT_FOR_SYSFS="ioerr_cnt" ACTION=="add", SUBSYSTEM=="scsi_device", SYSFS{type}=="0", RUN+="socket:/org/kernel/diskres/uevents" ACTION=="remove", SUBSYSTEM=="scsi_device", RUN+="socket:/org/kernel/diskres/uevents" So I do not see anything which could answer my question. There have been other rules for different sysfs types but I think they are not relevant in my case. In sysfs in /sys/bus/scsi/devices/7:0:0:8 I found: # ll block\:sdj lrwxrwxrwx 1 root root 0 Oct 4 17:57 block:sdj -> ../../../../../../../../../../block/sdj Where else can I look for the LUN<->/dev/ device mapping rules? How are the LUNs mapped to operating system devices? Is there a way to add a static mapping so that also on a new server after attaching SAN array LUN number 8 will be visible as /dev/sdj? I think that there is a possibility that on a new server mentioned LUN will be visible as a different /dev/sd? :( That could potentially break my logical volume setup on the destination server. Any info will be greatly appreciated :) BR, Rafal.

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Discuss October 2014