Memory Replacement

Fishworks gets de-duplication

2010-03-09T00:13:00.000-08:00

Sun's 7000 series storage products (known as Fishworks) are about to be updated with improved replication (much needed in our case) and de-duplication.

OpenSolaris 2010.03 + rsync == backup perfection?

2010-02-25T12:45:00.000-08:00

The release of OpenSolaris 2010.03 is going to add ZFS de-duplication to the already extensive list of ZFS features. De-duplication and the ZFS implementation are expertly explained on Jeff Bonwick's Blog. ZFS already sports a great double parity RAID implementation (known as RAID-Z2), excellent snapshot support, end-to-end checksumming, transparent compression and variable block sizes. The combination of theses features already make Solaris 10 and OpenSolaris great for backup servers, but the addition of de-duplication is going to make Sun's offerings unbeatable for this task.

With de-duplication, variable block sizes and compression saving your disk space, snapshots giving your backups history and the checksums giving you confidence in your backups' integrity, the only task left, is to get some data onto your backup server. Anyone who has ever used `rsync`, will tell you that it's the best tool for this job and, whilst I wholeheartedly agree, I am also interested to try out ZFS' replication. This allows you to transfer a snapshot (think incremental backup) or a whole file system (full backup) to a remote system using nothing more than `zfs`, a few pipes and `ssh`.

Debian installer on Xen post-install

2009-06-06T11:10:00.001-07:00

Here are a few things that I like to do to a Xen domU that's been installed by the Debian lenny installer:

# for foo in hooks scripts/init-premount; do 
    bar=/usr/share/initramfs-tools; 
    mkdir -p $bar/disabled/$foo; 
    dpkg-divert --divert $bar/disabled/$foo/thermal --rename $bar/$foo/thermal;
    done
# update-initramfs -tu
# update-rc.d -f hwclock.sh remove
# update-rc.d -f hwclockfirst.sh remove
#

The first couple of 'lines' disable the loading of thermal modules from the initial RAM disk. The last two lines disable reading from and wiring to the hardware clock (as it doesn't exist in the domU).

The following lines are mostly for me. I like to have 'xvda1' and 'xvda2' mapped to separate logical volumes on the dom0 and this makes Debian's grub implementation grumpy. It's worth doing, so that you can resize these logical volumes without messing with the partition table that would otherwise have been created on 'xvda'.

# sed -i /grub/d /etc/kernel-img.conf
# perl -pi -e 's#/boot(/[^-]+)-\S+(\s|$)#$1$2#' /boot/grub/menu.lst
#

The first line stops the Debian kernel packages' post installation scripts from running 'update-grub', which fails when no '/dev/xvda' exists. This does, however, mean that the grub menu will not be updated when a new kernel is installed. The second line mitigates this by updating the menu file to use the links in '/', rather than the specific paths to the files in '/boot/'. This should allow pygrub to boot new kernels as they are installed, even though the grub menu will not be updated.

Linux to Solaris

2009-02-18T00:28:00.000-08:00

For some time I've been interested in Solaris (particularly OpenSolaris) but I've never had the time or interest to take my explorations beyond installing the system and doing basic SysAdmin tasks. While reading some comments on an interesting blog post about 'The Enterprise Linux problem', I saw the following link:

http://opensolaris.org/os/community/advocacy/immigrants/

It provides links to some great posts that will help experienced SysAdmins get used to Solaris.

Comparison of console management techn{iques,ology}

2009-02-05T02:33:00.000-08:00

Here's a great bit of work by Ian Durkacz (University of Edinburgh, School of Informatics, April 2007) which compares various methods of remotely connecting to the console of a Linux server:

http://www.dice.inf.ed.ac.uk/units/infrastructure/Projects/06-Consoles/consoleoptions.pdf

It covers KVMoIP, multi-port serial cards, serial concentrators, IPMI and Dell Remote Access Cards (DRAC) and provides rough per-server prices.

Pipe viewer

2009-02-03T06:04:00.000-08:00

"Pipe viewer is a terminal-based tool for monitoring the progress of data through a pipeline. It can be inserted into any normal pipeline between two processes to give a visual indication of how quickly data is passing through, how long it has taken, how near to completion it is, and an estimate of how long it will be until completion."

http://www.catonmat.net/blog/unix-utilities-pipe-viewer/

Add partition devices on linux

2009-01-21T00:57:00.000-08:00

I often end up with a Linux block device or file which contains a PC partition table. The `kpartx` utility (part of the Linux multipath-tools) can create device nodes for partitions which were not detected at boot.

# kpartx -av /dev/loop1
add map loop1p1 : 0 144522 linear /dev/loop1 63
#

Remove 'NO_HW' devices from `ioscan`.

2008-12-10T04:22:00.000-08:00

When you pull a disk out of an HPUX system, `ioscan` will still show the device:

# ioscan -fnCdisk
Class     I  H/W Path     Driver S/W State   H/W Type     Description
=====================================================================
disk      0  0/1/1/0.0.0  sdisk CLAIMED     DEVICE       HP 73.4GST373454LC
                      /dev/dsk/c2t0d0   /dev/rdsk/c2t0d0
disk      1  0/1/1/0.1.0  sdisk NO_HW       DEVICE       HP 73.4GST373454LC
                      /dev/dsk/c2t1d0   /dev/rdsk/c2t1d0
disk      2  0/1/1/1.2.0  sdisk NO_HW       DEVICE       HP 73.4GST373454LC
                      /dev/dsk/c3t2d0   /dev/rdsk/c3t2d0

Here's how to remove all 'NO_HW' devices from the `ioscan` output:

ioscan -fCdisk|grep NO_HW|awk '{print $3}'|xargs -i -t rmsf -H {}

Finding a PID for a listening TCP port in Solaris

2008-10-27T00:43:00.000-07:00

From SunManagers:

On recent versions of Solaris, "pfiles" will tell you about each and every program running which file descriptor matches to what.
cd /proc
pfiles *| more

SUES/SLES Driver Update HOWTO

2008-07-24T05:47:00.000-07:00

ftp://ftp.suse.com/pub/people/hvogel/Update-Media-HOWTO/Update-Media-HOWTO.html

NoMachine NX - Remote desktop for UNIX

2008-07-09T07:31:00.000-07:00

http://www.nomachine.com/products.php

Replacing a Mirrored Disk in HPUX

2008-07-07T01:05:00.000-07:00

http://docs.hp.com/en/B2355-90950/ch06s02.html#bjabcaij

Cheap SSL Certificates

2008-06-19T02:34:00.000-07:00

http://www.trustico.co.uk/products/rapidssl/rapidssl.html

Process Explorer for Windows

2008-06-09T03:40:00.000-07:00

The Process Explorer display consists of two sub-windows. The top window always shows a list of the currently active processes, including the names of their owning accounts, whereas the information displayed in the bottom window depends on the mode that Process Explorer is in: if it is in handle mode you'll see the handles that the process selected in the top window has opened; if Process Explorer is in DLL mode you'll see the DLLs and memory-mapped files that the process has loaded. Process Explorer also has a powerful search capability that will quickly show you which processes have particular handles opened or DLLs loaded.

http://www.google.com/search?q=Process+Explorer

OSWA-Assistant Wireless Hacking ISO

2008-06-09T00:25:00.000-07:00

The OSWA-Assistant is a no-Operating-System-required standalone toolkit which is solely focused on wireless auditing. As a result, in addition to the usual WiFi (802.11) auditing tools, it also covers Bluetooth and RFID auditing. Using the toolkit is as easy as popping it into your computer's CDROM and making your computer boot from it!

http://oswa-assistant.securitystartshere.org/

WIFI Portal Software

2008-06-06T09:09:00.001-07:00

http://wiki.personaltelco.net/PortalSoftware

A Study of Passwords and Methods Used in Brute-Force SSH Attacks

2008-05-20T14:15:00.000-07:00

Quite interesting paper talking about the ever-increasing problem of ssh brute-force attacks:

http://people.clarkson.edu/~owensjp/pubs/leet08.pdf

Useful SuSE AutoYast Notes

2008-05-06T13:32:00.000-07:00

http://fong.homelinux.com/wordpress/?p=30

'yum-protectbase' vs. RHN

2008-04-27T15:44:00.000-07:00

I can't seem to get 'yum-protectbase' to behave correctly with RHEL5's rhnplugin. From `rpm -qi yum-protectbase`:

Description :
This plugin allows certain repositories to be protected. Packages in the protected repositories can't be overridden by packages in non-protected repositories even if the non-protected repo has a later version.

The problem is that, the RHN repositories aren't defined by standard files in '/etc/yum.repos.d/' so I can't add 'protect=1'. The same problem is documented here and here.

[EDIT]: This bug has now been fixed. See my comments on this post for details.

Dmidecode - print hardware information from your BIOS

2008-04-23T03:40:00.000-07:00

Dmidecode reports information about your system's hardware as described in your system BIOS according to the SMBIOS/DMI standard (see a sample output). This information typically includes system manufacturer, model name, serial number, BIOS version, asset tag as well as a lot of other details of varying level of interest and reliability depending on the manufacturer. This will often include usage status for the CPU sockets, expansion slots (e.g. AGP, PCI, ISA) and memory module slots, and the list of I/O ports (e.g. serial, parallel, USB).

Cross-subnet booting of HP-UX

2008-04-21T23:53:00.000-07:00

The following link describes how to set up an HP-UX 11i box as a "Boot-Helper System":

http://docs.hp.com/en/5992-3336/apds01.html

swinstall a specific version

2008-04-21T23:46:00.000-07:00

Here's how to swinstall a specific version of a depot, product or fileset:

swinstall -s ignite:/swdepot/Ignite/IgniteUX Ignite-UX.BOOT-KRN-11-11,r=C.6.8.152

Then verify it:

swlist -l fileset -a state Ignite-UX.BOOT-KRN-11-11

Testing mdadm's '--grow' option on RAID 5

2008-04-21T15:26:00.000-07:00

Here's a simple script to test mdadm's ability to grow a RAID 5 volume onto new disks. This is an amazing feature, which would previously have only been found on expensive hardware RAID solutions.

# Install the required tools.
sudo aptitude install ext2resize mdadm

# Set up the loop devices to be used as RAID
# devices.
for foo in `seq 0 4`; do dd if=/dev/zero bs=1M count=100 of=/tmp/$foo; sudo mknod /dev/loop$foo b 7 $foo; sudo losetup /dev/loop$foo /tmp/$foo; done

# Create a 4 'disk' RAID 5 on /dev/md5.
sudo mdadm -C -l 5 -n 4 /dev/md5 /dev/loop0 /dev/loop1 /dev/loop2 /dev/loop3

# You may want to wait for the initial (re)build to
# complete before proceeding.
watch 'sudo mdadm -D /dev/md5|tail -n 20'

# Make a file system on the RAID 5 volume.
sudo mke2fs /dev/md5

# Mount it up.
sudo mkdir /mnt/tmp
sudo mount /dev/md5 /mnt/tmp

# Create a 250MB test file.
sudo dd if=/dev/urandom bs=1M count=250 of=/mnt/tmp/file

# Take a checksum of the file.
md5sum /mnt/tmp/file|tee /tmp/file.md5sum

# Unmount the volume.
sudo umount /mnt/tmp/

# Add the 5th 'disk' and grow the volume.
sudo mdadm -a /dev/md5 /dev/loop4
sudo mdadm -G /dev/md5 -n 5

# You may want to wait for the grow operation to
# complete before proceeding.
watch 'sudo mdadm -D /dev/md5|tail -n 20'

# Resize the file system to fill the volume.
sudo ext2resize /dev/md5

# Mount it back up.
sudo mount /dev/md5 /mnt/tmp

# Verify that the file is unchanged.
md5sum -c /tmp/file.md5sum

# Unmount the volume.
sudo umount /mnt/tmp/
sudo rmdir /mnt/tmp

# Stop the RAID volume
mdadm -S /dev/md5

# Remove the loop devices and checksum file.
for foo in `seq 0 4`; do sudo losetup -d /dev/loop$foo; rm /dev/loop$foo /tmp/$foo; done
rm /tmp/file.md5sum

Recursively setting sensible permissions

2008-04-21T01:13:00.000-07:00

find . -type d -exec chmod 755 {} \; -or -type f -exec chmod 644 {} \;

UPDATE: Norgg and patrick have pointed out that the following, more simple command, does the same:

chmod -R a+rX .

Upgrading to DRBD 8.x from 0.7

2008-04-20T10:17:00.000-07:00

http://blogs.linbit.com/florian/2007/10/03/step-by-step-upgrade-from-drbd-07-to-drbd-8/

ssmtp: extremely simple MTA to get mail off the system to a mail hub

2008-04-18T11:52:00.000-07:00

A secure, effective and simple way of getting mail off a system to your mail hub. It contains no suid-binaries or other dangerous things - no mail spool to poke around in, and no daemons running in the background. Mail is simply forwarded to the configured mailhost. Extremely easy configuration.

http://packages.debian.org/stable/mail/ssmtp

Mapping Edinburgh Pubs

2008-04-14T14:23:00.000-07:00

HP 2133 miniNote 1.2GHz 2GB XP Pro 6 Cell from RM

2008-04-14T04:06:00.001-07:00

http://www.rm.com/HE/Products/Product.asp?cref=PD1164671

Xvnc with inetd

2008-04-09T02:58:00.000-07:00

Here's how to use Xvnc with inetd to allow users to use a VNC client to get to an xdm:

http://www.realvnc.com/products/free/4.1/man/Xvnc.html#lbAG

As RHEL 5 uses xinetd I created '/etc/xinetd.d/Xvnc' with the following contents:

# default: off
# description: Xvnc server which talks XDMCP to a local xdm in order
# to give the user a local GUI login prompt.
service Xvnc
{
disable = no
port = 5900
socket_type = stream
wait = no
user = nobody
server = /usr/bin/Xvnc
server_args = -inetd -query localhost -once securitytypes=none
log_on_failure += HOST
}

GNOME's vino might also be of interest but it's designed for connecting to running GNOME sessions.

How to specify a configuration file for pxelinux from ISC DHCP server 3

2008-04-04T03:35:00.000-07:00

option space pxelinux;
option pxelinux.magic code 208 = string;
option pxelinux.configfile code 209 = text;
site-option-space "pxelinux";
option pxelinux.magic f1:00:74:7e;
if exists dhcp-parameter-request-list {
# Always send the PXELINUX options (specified in hexadecimal)
option dhcp-parameter-request-list = concat(option dhcp-parameter-request-list,d0,d1,d2,d3);
}
option pxelinux.configfile "pxelinux.cfg";

Forwarding queries to local (no TLD) DNS zone

2008-04-03T14:12:00.000-07:00

How do you get one name server to talk to another one, when you're using a local domain (one with no registered TLD)?

Use the 'forward' zone type and specify the remote name server to query:

zone "jdt" {
type forward;
forward only;
forwarders { 192.168.0.200; };
};

Train posters for Dad's birthday

2008-04-02T08:44:00.000-07:00

http://www.you-see-red.com/printroom/search/category.cfm?cat=56