Monday, July 28, 2014

Useful SSH configs

Put these in ~/.ssh/config

They help with repetitive tasks and such

Host *
     Compression yes
     ForwardX11 yes
     CompressionLevel 7
     Cipher blowfish
     ServerAliveInterval 600
     ControlMaster auto
     ControlPath /tmp/ssh-%r@%h:%p
     StrictHostKeyChecking no

Host 100.7.*
     StrictHostKeyChecking no
     UserKnownHostsFile=/dev/null

Sunday, July 27, 2014

Kytronic Smart Booster 2

After thinking about this for almost 20 years, finally someone made one!

Key features of Smart Booster2 include:

Increases significantly acceleration and power

Reduces mechanical stress and temperature at high-rpm

Reduces gas consumption

Plug-and-Play, simple to setup, no battery needed

16 ignition timing curves, tailored to your engine for best efficiency

Protected under epoxy resin in a customized red ABS plastic case

http://www.kytronik.com/sb2

Here is a quick photo gallery of my install process and as a bonus I had to replace all of the wiring on the stator plate.

As it arrived, with free sticker!!

Old timing marks, I actually had it set more advanced than this as you can tell from the modified slots.

Real vintage wiring!

Reboot...

...with heat shrink

unit fitted (need to replace that dodgy looking coil though)

New timing Marks. My bike is kitted with a Polini so it likes to fire @ 2mm from BTDC, or around 18 degrees. This unit changes all that, it will advance it where it needs to then back it off at higher revs to lower temp, and smooth out the engine. I'm running a squish clearance of almost 2mm and I monitor the cylinder head temp so I feel comfortable running it at around 18 degrees advance at high revs, hopefully even in Sydney summer time.

Sunday, July 06, 2014

Getting rid of 4-stroking - The quest

Overview

In my last post I said that I had been trying to get rid of my scooters 4 stroking for over 10 years. It's actually quite a lot longer than that actually, and it's really starting to but me. I've decided to jot everything down in this blog in at attempt to make it less baffling (no pun intended) and possibly help anyone else that has a similar issue.

In the last post I went over the port timing, this time I'll go over the carb jetting.

Descriptions of symptoms

The thing that I can't get my head around is that everything I read tells me that 4-stroking is due to being too rich (we actually the cause is that the scavenging effect of the 2 stroke process isn't getting a chance to work on the amount of gas in the cylinder, so we could look at retarding the timing - more on that later). The thing is, if I lean out the idle any more it is just too lean., very slow to die down to idle speed, uneven, no power to pull off. But if I get the mixture "just right", the idle is nice and constant at around 1500rpm. The problem is as soon as I am moving and I position the throttle "just" off idle, the engine 4-strokes.

Current settings

I have a Dellorto 28 PHPB with a Ram-Air foam filter.
Main - 128
Pilot - 55
Choke - 70
Slide - 60 (modified)
Needle - x2 (middle ring)
Atomiser - AV262
White float

Today I tried once again messing around with the air mixture, and took the air filter off to see if that was causing the bike to run rich off idle. Neither helped.

Next I retarded the timing by a couple of degrees to around 17 BTDC, this actually seemed to make the engine more rough in other places (which I can understand, the low down torque would be better with more advance, my variable timing module is on the way). Anyway, the timing retard didn't help the 4-stroking issue.

Conclusion

I'm beginning to think that all kitted Vespas do this.

EDIT

I started to think that I might be overcompensating for the lean slide by an over rich idle mixture setting (it was around 3 turns out). The two circuits to overlap quite a lot, especially in higher idle screw settings.

So I changed my over lean 60 slide for a 50 (unmodified) and swapped the 55 pilot jet for a 50.

At first it was over rich everywhere, but I after some adjustment I was able to get the idle pretty nice, screw is around 2.5 turns out which is correct for the PHBH carb. Middle openings where very rich so I lowered the needle to it's most lean position (top notch).

The engine pulls well now and the 4 stroking is much better. It is still there though, but at least I know the engine is not too lean!

Depending on the weather I might need to change the atomiser for a AV260 and raise the needle right up but I want to play it safe for now.

I did a plug chop and it's nice and brown. Max CHT was 149 degrees C after a good WOT blat.

I'm hoping that the variable ignition timing unit will help even more.

EDIT 2

See next post when I finally solve this!

Wednesday, July 02, 2014

Vespa - Polini 208 Port timing

Port Timings

Background

Ever since I put a 60mm crank on scooter I have been suspicious that the port timing had been messed up. I remember about 10 years ago I rang Terry at Taff speed, when he was still alive, and he told me that I should stick with the 57mm crank. I had already put the long stroke crank in at that stage so I couldn't bear undoing all of the work (or money).

Symptoms

Difficulty getting the low speed jetting right.
Rough running just off idle (4 stroking)

Forward wind lots of years and I finally got a chance to take a proper look, hopefully anyone else with a similar kit will find my findings useful.

Current build

PX200 engine
Cast iron Polini 208 kit, port matched transfer ports in the casings.
A Worb5 head machined for the long stroke crank (it has a 1.5mm squish and the plug is moved toward the centre).
A 60mm racing crank
SIP 1.5KG full size balanced racing flywheel
28mm Delorto
SIP racing clutch (very nice)
SIP clutch bearing actuator
Max. CHT temp. 160 Degrees C
Max compression 150psi (warm, WOT).
Ignition timing 19 degrees BTDC

I was running the kit with no base gasket and no head gasket.

The squish was around 1.2mm which is about ideal for racing (Norris Ker recommends 1mm in his book).

The jetting was about right (apart from the 4 stroking bottom end, usually found due to being to rich). I've been playing with jetting and slide modifications for years and still not got it perfect.

Ignition timing was around 19 BTDC (or around 2.5mm piston movement).

Stock Polini port timings

"Apparently" the stock Polini kit has port timings of 123° transfers to 171°exhaust timing with the 57mm crankshaft, but that information does vary depending on where I find it on the web.

Another site said 161.2; 112.8; 21.2 which is miles off what I found and I do question.

My port timings

My initial port timings with this set up where:

Exhaust port open: 262 degrees
Transfer open: 238 degrees
Transfer close:115 degrees
Exhaust close: 91 degrees

The sums

Exhaust port open - Exhaust close = exhaust port duration

Transfer open - Transfer close = transfer duration

Exhaust port duration - exhaust port duration / 2 = Blowdown

Exhaust duration: 171 degrees
Transfer duration: 123 degrees
Blowdown: 24 degrees

This is pretty much exactly what I had found the Polini 208 kit to be, so the long stroke hadn't really effected the port timing much, if at all. I did want to get the rough running sorted though so I elected (easy to vote when there is only one of you) to install the base gasket which did alter the port timings a little.

Piston just clearing the transfer port.

Finding TDC

Modified Port Timings

"To alter or not to alter"

I chose not to alter the height of the exhaust port, even though my calculations found that I my ports timings where very close to the edge of what is recommend. I put this down to Mr. Polini knowing best and left it there. Besides, I want a grunty engine for riding around town, I've given up on the super high revving 2 stroke scooters.

Taken from http://www.race-base.com/2t-tools/steuerzeit/

So all I ended up doing was cleaning up all of the ports up a bit, and installing a 0.3mm base gasket and a 0.7mm head gasket. This gave me the following set-up.

Exhaust duration: 174 degrees
Transfer duration: 125 degrees
Blowdown: 24.5 degrees
Squish clearance: 1.9 mm

Some greasy scribblings

I also backed off the ignition timing to 18 degrees BTDC

Test ride

With the slightly revised port timing, the relaxed ignition timing and the reduced compression the engine feels smoother across the rev range, and does tend to reach high revs more easily (not a surprise as I have marginally raised the port timings. Given the reduction in compression I was surprised it still pulls very well.

CHT measured at a MAX. of 151 degrees which is quite acceptable.

Conclusion

All in all it was worth while to go through this exercise, one to put my mind at rest about the timings, but also because the bike does go better.

It does still 4 stroke a little just off idle though...

Friday, November 22, 2013

ZFS Server build notes

ZFS Filesystem backup

Hostname	xxxx
OS	centos6.2 64
10GB	Yes
MTU	9000
IP Address	xx.xx.xx.xx
VLAN	backup & archive
Location	xxxxx

Storage Layout

Device	Size	Type	Compression	Comments
Raid6_sys	120GB	Raid6	No	Hardware Raid on Adaptec Raid Card - 1 hot spare
Raid_data	2.5TB	Raid6	No	Hardware Raid on Adaptec Raid Card - 1 hot spare
SATA	1TB	EXT4	No	Clone of System
RaidZFS	XXTB	ZFS	Yes	Main Backup Storage

Installation Notes

Centos requires the Adaptec module to be installed during the install process in order to see the local raid

http://ask.adaptec.com/app/answers/detail/a_id/17150

The Mellonx 10G card needs a drive compiled and installed (make sure gcc, make, rpm_build_tools etc is installed!). The install files are in the homedir of root.
BIOS is password locked with password
Adaptec Raid Controller is password locked with password
Full yum update performed - 21.11.2013
Mellonx En driver doesn't load on it's own at start up. Fix this by adding the following to /etc/rc.local - modprobe mlx4_en
Installed Megacli to talk to the LSI raid controller - rpm -ivh MegaCli-8.07.08-1.noarch.rpm
Disable selinux - it's not supported with zfs at the moment.

LSI Controller Admin

We will use MegaCLI to communicate with the LSI controller

https://calomel.org/megacli_lsi_commands.html

 lsi.sh help

The controller is set to mail alerts. This is done via the root crontab

00   */2  *   *   *   /usr/local/bin/lsi.sh checkNemail

View enclosures

/opt/MegaRAID/MegaCli/MegaCli64 -EncInfo -aALL

Creating the raid0 devices to present each disk to the OS

i=0; while [ $i -le 23 ] ; do /opt/MegaRAID/MegaCli/MegaCli64 -cfgldadd -r0[8:${i}] WB RA Cached CachedBadBBU -strpsz512 -a0 -NoLog ; i=`expr $i + 1`; done
i=0; while [ $i -le 23 ] ; do /opt/MegaRAID/MegaCli/MegaCli64 -cfgldadd -r0[9:${i}] WB RA Cached CachedBadBBU -strpsz512 -a0 -NoLog ; i=`expr $i + 1`; done

Note that the enclosure ID's are 8 and 9. We can find this doing.

/opt/MegaRAID/MegaCli/MegaCli64 -EncInfo -aALL

Check the status of the drives

lsi.sh status
lsi.sh drives

Information on a disk (in this case Enclosure 8, disk 20)

/opt/MegaRAID/MegaCli/MegaCli64 -PDInfo -PhysDrv [8:20] -a0

Rebuild disk (in this case Enclosure 8, disk 20)

/opt/MegaRAID/MegaCli/MegaCli64 -PDRbld -Start -PhysDrv [8:20] -a0

Misc. commands

Enable controller alarm

/opt/MegaRAID/MegaCli/MegaCli64 -AdpSetProp AlarmEnbl -aALL

Disable controller alarm

/opt/MegaRAID/MegaCli/MegaCli64 -AdpSetProp AlarmDsbl -aALL

Good cheat sheet of MegaCLI commands: http://www.damtp.cam.ac.uk/internal/computing/docs/public/megacli_raid_lsi.html

Install ZFS

yum localinstall --nogpgcheck http://archive.zfsonlinux.org/epel/zfs-release-1-2.el6.noarch.rpm
yum install dkms gcc make kernel-devel perl
yum install spl zfs
chkconfig zfs on

Create ZFS Raid

zpool create -f tank /dev/sdf /dev/sdg /dev/sdh /dev/sdk /dev/sdj /dev/sdi /dev/sdl /dev/sdn /dev/sdm /dev/sdp /dev/sdo /dev/sdq /dev/sdr /dev/sds /dev/sdt /dev/sdu /dev/sdv /dev/sdx /dev/sdw /dev/sdy /dev/sdz /dev/sdaa /dev/sdab /dev/sdac /dev/sdad /dev/sdae /dev/sdaf /dev/sdai /dev/sdah /dev/sdaj /dev/sdag /dev/sdal /dev/sdam /dev/sdak /dev/sdan /dev/sdaq /dev/sdao /dev/sdar /dev/sdat /dev/sdas /dev/sdav /dev/sdap /dev/sdau /dev/sdaw /dev/sdax /dev/sday
zpool add tank spare /dev/sdd /dev/sdb
zfs create tank/projects
zfs set compression=lzjb tank/projects
zfs set dedup=on tank/projects
zfs set atime=off tank
zfs set atime=off tank/projects

What is looks like

# zfs list
NAME            USED  AVAIL  REFER  MOUNTPOINT
tank           1.38M   164T   144K  /tank
tank/projects   136K   164T   136K  /tank/projects

Common Tools

Check dedupe ratio

zpool get dedupratio tank

Snapshots

Running from cron

# ls -l /etc/cron.* |grep zfs
-rw-r--r--. 1 root root  79 Nov 21 17:24 zfs-auto-snapshot.cron.daily
-rw-r--r--. 1 root root  80 Nov 21 17:24 zfs-auto-snapshot.cron.hourly
-rw-r--r--. 1 root root 81 Nov 21 17:26 zfs-auto-snapshot.cron.monthly
-rw-r--r--. 1 root root 79 Nov 21 17:26 zfs-auto-snapshot.cron.weekly

These crons run

/usr/local/bin/zfs-auto-snapshot

Current snapshot schedule is to keep 12 months of snapshots. These are located in .zfs of each folder.

Display snapshots config

zpool get listsnapshots tank

List snapshots

zfs list -r -t snapshot -o name,creation tank  
zfs list -t snapshot

List space

zfs list -o space

Advanced reading https://pthree.org/2012/12/17/zfs-administration-part-x-creating-filesystems/

Devices

Disk /dev/sdd: 4000.2 GB, 4000225165312 bytes
Disk /dev/sde: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdf: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdg: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdh: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdk: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdj: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdi: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdl: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdn: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdm: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdp: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdo: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdq: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdr: 4000.2 GB, 4000225165312 bytes
Disk /dev/sds: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdt: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdu: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdv: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdx: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdw: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdy: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdz: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdaa: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdab: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdac: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdad: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdae: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdaf: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdai: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdah: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdaj: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdag: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdal: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdam: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdak: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdan: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdaq: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdao: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdar: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdat: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdas: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdav: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdap: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdau: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdaw: 4000.2 GB, 4000225165312 bytes
Disk /dev/sdax: 4000.2 GB, 4000225165312 bytes
Disk /dev/sday: 4000.2 GB, 4000225165312 bytes)

Tuesday, November 19, 2013

Create Bootable USB from ISO on OSX

I found this page very useful

Friday, November 08, 2013

GNG Electric Mid Motor bearing replacement - more info

Thursday, November 07, 2013

Changing the bearings on my two week old GNGElectric bicycle motor.

Monday, November 04, 2013

Stereo xorg.conf - Centos playback machine to a Barco DP90 using SDI

=== Playback Hardware ====

The playback machine in the theater is called rodoric. It has 2 SSD 500GB drives, hardware raided.

/dev/sda1 937G 614G 277G 69% /ssd

The graphics card is a Nvidia 4000. It has 3 connections, only two are in use at one time.

* In Mono mode it will use a DVI to the KVM extender, and a DVI to a DVI-Ramp which in turn converts it's signal to SDI into the Barco (Input A)
* In Stereo mode it will output Left and Right eye signals using both display ports through DVI into a single DVI-Ramp which in turn converts it's signals to SDI into the Barco (SDI input A and B)

Users can switch between Stereo and Mono using the xorgswitch file below.

=== Xorg Switch ===

Type xorgswitch in a terminal to switch between Stereo and Mono Display modes
xorgswitch

#!/bin/bash

#switch the xorg files for stereo and regular playback
#v1.0 - Dylan Penhale 04-11-2013

X11PATH=/etc/X11
XORG3D=xorg.conf.rv.3d.WORKING.04.11.2013
XORG2D=xorg.conf.safe.31.10.2013

echo "1. Stereo Mode - Barco only"
echo "2. Mono - Barco and LCD display"
echo -n "Enter: [1 or 2]:"
read choice

if [ $choice -eq 1 ]; then
echo "Switching xorg to Stereo mode"
rm -rf $X11PATH/xorg.conf
cp $X11PATH/$XORG3D $X11PATH/xorg.conf
echo "Now restart X Server {Cntl+Alt+Backspace)"
exit 0
else
if [ $choice -eq 2 ]; then
echo "Switching xorg to Mono mode"
rm -rf $X11PATH/xorg.conf
cp $X11PATH/$XORG2D $X11PATH/xorg.conf
echo "Now restart X Server {Cntl+Alt+Backspace)"
exit 0
fi
fi

done

=== Stereo ===

/etc/X11/xorg.conf.rv.3d.WORKING.04.11.2013

Section "ServerLayout"
Identifier "Layout0"
Screen 0 "Screen0" 0 0
InputDevice "Keyboard0" "CoreKeyboard"
InputDevice "Mouse0" "CorePointer"
Option "Xinerama" "0"
EndSection

Section "Files"
FontPath "/usr/share/fonts/default/Type1"
EndSection

Section "InputDevice"

# generated from default
Identifier "Mouse0"
Driver "mouse"
Option "Protocol" "auto"
Option "Device" "/dev/input/mice"
Option "Emulate3Buttons" "no"
Option "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"

# generated from data in "/etc/sysconfig/keyboard"
Identifier "Keyboard0"
Driver "keyboard"
Option "XkbLayout" "us"
Option "XkbModel" "pc105"
EndSection

Section "Monitor"

# HorizSync source: edid, VertRefresh source: edid
Identifier "Monitor0"
VendorName "Unknown"
ModelName "OEM DVI-Ramp2"
HorizSync 1.0 - 250.0
VertRefresh 10.0 - 250.0
ModeLine "2048x1080_24.00" 66.02 2048 2080 2280 2512 1080 1081 1084 1095 -hsync +vsync
Option "DPMS"
EndSection

Section "Device"
Identifier "Device0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "Quadro 4000"
EndSection

Section "Screen"

# Removed Option "Stereo" "4"
# Removed Option "metamodes" "DFP-1: 2048x1080_24 +0+0, DFP-2: 2048x1080_24 +0+0; DFP-1: nvidia-auto-select +0+0, DFP-2: nvidia-auto-select +0+0"
# Removed Option "metamodes" "DFP-0: nvidia-auto-select +64+0, DFP-2: 2048x1080_24.00 +0+60; DFP-2: nvidia-auto-select +0+0"
Identifier "Screen0"
Device "Device0"
Monitor "Monitor0"
DefaultDepth 24
Option "CIOverlay" "on"
Option "Overlay" "on"
Option "TwinViewOrientation" "Clone"
Option "ExactModeTimingsDVI" "TRUE"
Option "FlatPanelProperties" "Scaling = Native"
Option "TwinView" "1"
Option "nvidiaXineramaInfoOrder" "DFP-0"
Option "Stereo" "4"
Option "metamodes" "DFP-1: 2048x1080_24.00 +0+0, DFP-2: 2048x1080_24.00 +0+0; DFP-2: nvidia-auto-select +0+0"
SubSection "Display"
Depth 24
EndSubSection
EndSection
Section "Extensions"
Option "Composite" "Disable"
Endsection

=== Mono ===

/etc/X11/xorg.conf.safe.31.10.2013

Section "ServerLayout"
Identifier "Layout0"
Screen 0 "Screen0" 0 0
InputDevice "Keyboard0" "CoreKeyboard"
InputDevice "Mouse0" "CorePointer"
Option "Xinerama" "0"
EndSection

Section "Files"
FontPath "/usr/share/fonts/default/Type1"
EndSection

Section "InputDevice"
# generated from default
Identifier "Mouse0"
Driver "mouse"
Option "Protocol" "auto"
Option "Device" "/dev/input/mice"
Option "Emulate3Buttons" "no"
Option "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"
# generated from data in "/etc/sysconfig/keyboard"
Identifier "Keyboard0"
Driver "keyboard"
Option "XkbLayout" "us"
Option "XkbModel" "pc105"
EndSection

Section "Monitor"
# HorizSync source: edid, VertRefresh source: edid
Identifier "Monitor0"
VendorName "Unknown"
ModelName "Eizo S2411W"
HorizSync 31.0 - 76.0
VertRefresh 59.0 - 61.0
Option "DPMS"
EndSection

Section "Device"
Identifier "Device0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "Quadro 4000"
EndSection

Section "Screen"
Identifier "Screen0"
Device "Device0"
Monitor "Monitor0"
DefaultDepth 24
Option "Stereo" "0"
Option "nvidiaXineramaInfoOrder" "DFP-0"
Option "metamodes" "DFP-0: 1920x1200 +0+0, DFP-2: 2048x1080_24 +1920+60"
SubSection "Display"
Depth 24
EndSubSection
EndSection

Sunday, October 06, 2013

Howto repair XT shifters.

My first tech blog

Saturday, August 24, 2013

Short XC Single Track Loop - Belrose 720P

Quarry Track (Sydney) MTB

Playing with the new helmet Cam... The mount needs some work!

Friday, August 23, 2013

Find duplicates in bash

find_dupes.sh

#! /bin/bash
OUTF=rem-duplicates.sh;
echo "#! /bin/sh" > $OUTF;
echo "" >> $OUTF;
find "$@" -type f -print0 | xargs -0 -n1 md5sum | sort --key=1,32 | uniq -w 32 -d --all-repeated=separate | sed -r 's/^[0-9a-f]*( )*//;s/([^a-zA-Z0-9./_-])/\\\1/g;s/(.+)/#rm \1/' >> $OUTF;
chmod a+x $OUTF

Run the script:

./find_dupes.sh /path/to/check .\

Which will output a file called rem-duplicates.sh which can then be edited as you wish.

I stole this from here. Credit to Marco Fioretti, who in turn used code from J. Elonen

LED lights on my Vespa

Friday, August 16, 2013

Getting started with Linux in VFX

Useful entry level reading for someone that's never used linux before....

http://www.creativecrash.com/tutorials/the-unix-shell-for-vfx-artists#tabs

Thursday, August 15, 2013

VFX pipeline diagram - real world example

Taken from a pipeline design meeting.

Credit to Simon Maddison I think

Wednesday, August 14, 2013

How to setup a reverse ssh tunnel

Ever wanted to know how you can ssh into your work desktop/server? Well do not worry any longer.....

- ssh -nNT -R 5000:local_server:22 username@remote_server
- Now from the remote_server run this
  ssh -p5000 localhost.... now we are in our work desktop/server.
- The -n option Redirects stdin from /dev/null. This must be used when ssh is run in the background.
- The -N option does not execute a remote command. This is useful for just forwarding ports.
- The -T option disables pseudo-tty allocation.
- The -R option does tha job of setting up the reverse tunnel.
- Port 5000 is the port that will be listening on the remote_server (this can be any random port over 1024, if you want to run this as a non-root user).
- local_server is the desktop/server that you are creating the connection from.
- Port 22 is the port that you are making the ssh connection to.
- user_name@remote_server is where you are making the ssh connection to for the reverse tunnel.

We need to make sure we keep this connection open

In /etc/ssh/sshd_config we need to make sure this is set TCPKeepAlive yes.\

This page was stolen from somewhere else, I can't remember where. Sorry to the original author..

Running a script as root

The problem:

In theory, running a script as it's owner (in our case root) is simple, all you have to do is set the 'setuid' bit (sometimes mistakenly called the 'sticky' bit) by using 'chmod 4755' (or chmod 4***, depending on what mode you need). The problem is, that the 'setuid' bit functionality has been disabed on most Linux based distros for security reasons. This affects only scripts, not compiled code which should still work.

Solutions:

binary wrapper

The 'setuid' bit still works for compiled files. So what you can do is write a little c wrapper that will execute the script you want to run as root.

#include 
#include 
#include 
#include 

using namespace std;

int main(int argc, char* argv[]) {
    setuid( 0 );
    string cmd = "/opt/local/cmd.sh";
    for (int i = 1; i < argc; i++) {
        string arg (argv[i]);
        cmd += " ";
        cmd += arg;
    }
    int exitcode;
    exitcode = system(cmd.c_str());
    return WEXITSTATUS(exitcode);
}

Safe this as 'runscript.c', then compile and do the following:

gcc runscript.c -o runscript
sudo chown root:root runscript
sudo chmod 4750 runscript

You should now be able to run this command as root.

sudo wrapper

Add the following line to your sudoers file, with 'group' being the group you want to give access to your script.

group    ALL = NOPASSWD: /path/to/script

Then write a wrapper, executing you script with sudo.

sudo /path/to/script

Also your script will have to perform a 'setuid(0)' to make sure that all child processes are executed as root.

A couple of things to note:

it's not enough to do 'chmod 4***' on the binary, you also have to use 'setuid' inside the code.
an additional problem on Mac OS X is, that by default the 'setuid' bit is disabled on NFS mounts.

x forward session with xdmcp

XDMCP allows logging into a remote host, but displaying the desktop on your own host.

1) edit /etc.gdm/custom.conf

[xdmcp]
Enable=true

[security]
DisallowTCP=false
AllowRemoteRoot=true

2) restart X (telinit 3; telinit 5)

3) login as root and run:

gdmsetup

4) On the remote tab, change 'style' to 'same as local'

5) On the security tab, tick 'allow local system administrator login' and 'allow local system administrator login'

6) restart X

To test, log off your host, and press F10 in the login GDM login window. You can enter the name of the remote host to login too here.

Forward user x sessions

When logging into a remote host as root, you lose the ability to forward x sessions after an su to another user.

To allow x-forwarding after you perform an su, you need to request the cookie for the current server:

ssh root@somehost

xauth list

returns:

 somehost.somedomain/unix:10  MIT-MAGIC-COOKIE-1  d9fc3512df83a70ea8054dff21f58e28

Now, su to the user:

su - someuser

xauth add somehost.somedomain/unix:10  MIT-MAGIC-COOKIE-1  d9fc3512df83a70ea8054dff21f58e28

now x apps will forward correctly - test with xterm.

Labels

Monday, July 28, 2014

Sunday, July 27, 2014

Sunday, July 06, 2014

Overview

Descriptions of symptoms

Current settings

Conclusion

EDIT

EDIT 2

Wednesday, July 02, 2014

Port Timings

Background

Symptoms

Current build

Stock Polini port timings

My port timings

The sums

Modified Port Timings

Test ride

Conclusion

Friday, November 22, 2013

Tuesday, November 19, 2013

Friday, November 08, 2013

Thursday, November 07, 2013

Monday, November 04, 2013

=== Playback Hardware ====

=== Xorg Switch ===

=== Stereo ===

=== Mono ===

Sunday, October 06, 2013

Saturday, August 24, 2013

Friday, August 23, 2013

Friday, August 16, 2013

Useful entry level reading for someone that's never used linux before....

Thursday, August 15, 2013

Wednesday, August 14, 2013

The problem:

Solutions:

binary wrapper

sudo wrapper

A couple of things to note: