Moving "Documents and Settings" to another partition in Windows XP

Because you can't depend on Windows, it's nice to have some kind of backup scheme for when things go wrong. One of those solutions is to store important data on a seperate drive. I've seen a lot of people doing this the wrong way. User folder in C:\Documents and Settings\[user] and a partition D: or E: which then contains folders like Documents, Downloads, Photos and Music.

A home directory is not just a home directory for nothing, so store your files in there. The solution is simple, with NTFS drivers you can have a volume mount point, which allows you to use a seperate NTFS filesystem as if it was just a folder in another NTFS filesystem. Of course this doesn't make it easy yet, so these are the steps that need to be taken to have it fully functional:

1. Format the new partition as NTFS
2. In Disk Management in Windows setup the new filesystem as volume mount point on C:\newdoc
3. Boot to something that is capable of moving stuff around on your drive (Parted Magic will do)
4. Copy the contents of Documents and Settings to the new filesystem
5. Move Documents and Settings to olddoc
6. Move newdoc to Documents and Settings
7. Reboot into Windows

Depending on what you used to copy the contents of Documents and Settings you might have to reset some of the file attributes (or permissions even), because otherwise a lot of Desktop.ini files will pop up.

One last improvement that can be made is to fix the icon for the mount point. By default this will show as a disk icon, but because we abstracted this fact we might also want to show it as a folder. Just create C:\Documents and Settings\autorun.inf with the following contents:

[autorun]
icon=%SystemRoot%\system32\SHELL32.dll,3

This requires a reboot before visible, but after that will work great.

Because we make effective use of NTFS volume mount points all legacy applications that probe for C:\Documents and Settings instead of using the proper functions to find profile directories will work as ever before. Just keep in mind to follow these steps after a Windows reinstall, except for the file copy part!

Linksys E4200 as an access point

At work we bought two Linksys E4200's to extend our wireless network. We wanted to use them as access points / wireless gateways instead of their normal router configuration. Googling turns up a few half-documented solutions, which might even work in case you've got a small home network set up, but I still couldn't get it to work. So I took one of the routers home, and this is what I've come up with (tested at home only right now):

1. Start the router
2. Connect a cable between your computer and one of the E4200 LAN ports
3. Turn on remote management on the E4200
4. Verify that the E4200 doesn't have a local address that belongs in your network's subnet (change it otherwise)
5. Connect a cable between the E4200 WAN port and your network
6. Connect a cable between your computer and network
7. Turn off the DHCP server on the E4200
8. Connect a cable between your network and one of the E4200 LAN ports
9. Connect a cable between the E4200 WAN port and one of the E4200 LAN ports

Now you can wirelessly connect to your network using the E4200 and you can still access the E4200 admin interface as well!

Of course this all won't be necessary when DD-WRT or other alternative firmware releases are available for the E4200, but right now this probably is the best solution.

touchmoused: Logitech Touch Mouse server for Linux

Recently I was looking at a way to control the Mac Mini I have connected to my TV. I don't have a keyboard or mouse connected (only a gamepad), but I do have an iPod Touch. Soon I found Logitech Touch Mouse, a simple app providing a keyboard and mouse over the network. Of course Logitech isn't capable of delivering a Linux server for it's app, so I decided to write it myself.

After a quick Wireshark dump I started hacking away. Using the recently released Shairport as a reference I started hacking away on my first Perl program. This also being my first program where I had no documentation on protocol whatsoever, it took me a while to figure out I had to listen both on TCP and UDP. Then it also took me a while before I figured Perl doesn't write directly on a print statement unless autoflush is set on the file descriptor. I managed to find that one on a page detailing serial port communication with Perl.

When these hurdles were overcome I could really start interpreting events, sending them through to the Linux UInput facility. Today another big issue was fixed, mouse movement was broken until I added left mouse button support. So anyone trying to send mouse movements using uinput, be sure to enable left mouse button events!

Anyway, I've now come to a point where the Touch Mouse app can be effectively used as a trackpad replacement. Moving, clicking, (two-finger) scrolling, it all works. Also alphanumeric keys are working, Ctrl and Alt are working and some character keys are working. This also means I think I've come far enough to promote the app here on my blog, so anyone willing to try it out should move on to my github project page.

DHCP for PXE booting only

At work we use a Novell Netware 5 server (don't worry, it will be replaced) for, amongst others, DHCP. Not much of an issue, but I wanted to netboot clients so I could do easy operating system installations. When I wanted to add the appropriate options to the DHCP server, I noticed it wasn't possible. Some searching on the internet revealed some hacks, but nothing you'd easily try on a server in use.

So then what? I noticed before when I was trying to boot PXE clients and they were attached to the main network (instead of my private network) that they wouldn't get (accept?) DHCP leases, so there was my solution: add a DHCP server that gives leases to PXE clients only.

Although this may sound hard, it's actually pretty easy. PXE clients send along a so-called vendor class identifier containing the string PXEClient. Using the ISC DHCP server we can easily check for this string, and then hand out a lease to those clients only. One last thing to keep in mind: don't hand out leases in the same range as the authorative DHCP server.

Finally, here's a sample config (/etc/dhcp3/dhcpd.conf):

ddns-update-style none;
option domain-name "mycroes.nl";
option domain-name-servers 192.168.5.1;

default-lease-time 600;
max-lease-time 7200;
log-facility local7;

class "pxeclients" {
 match if substring(option vendor-class-identifier, 0, 9) = "PXEClient";
 filename "pxelinux.0";
}

shared-network 5 {
 subnet 192.168.5.0 netmask 255.255.255.0 {
 }
 pool {
  allow members of "pxeclients";
  range dynamic-bootp 192.168.5.201 192.168.5.240;
 }
}

Updating Ubuntu without removing grub-efi

Ubuntu still is trying to remove grub-efi everytime a new kernel arrives. I have a Mac Mini without a display, so grub-pc is useless for me, so how do I prevent this grub-efi removal all the time?

Simple solution, just tell apt you also want to install grub-efi, regardless of the availability of a new version:

$ sudo apt-get install linux-generic-pae grub-efi
Reading package lists... Done
Building dependency tree       
Reading state information... Done
grub-efi is already the newest version.
The following extra packages will be installed:
  linux-image-2.6.35-22-generic-pae linux-image-generic-pae
Suggested packages:
  fdutils linux-doc-2.6.35 linux-source-2.6.35 linux-tools
Recommended packages:
  grub-pc grub lilo
The following NEW packages will be installed:
  linux-image-2.6.35-22-generic-pae
The following packages will be upgraded:
  linux-generic-pae linux-image-generic-pae
2 upgraded, 1 newly installed, 0 to remove and 3 not upgraded.
Need to get 34.1MB of archives.
After this operation, 107MB of additional disk space will be used.
Do you want to continue [Y/n]?

And voila, grub-pc is a suggested package and no longer forced upon me! Thanks go out to Frank Groeneveld for suggesting the solution!

Installing Samba 4 on Ubuntu Maverick (10.10)

Samba 4 is currently able to serve as a active directory domain controller for both Windows XP and Windows 7 (as tested by me) and probably for other Windows versions too. With Ubuntu 10.10 there finally is a recent enough version to make use of all the current Samba 4 functionality, however some issues still remain. This post will provide a short guide to setting up Samba 4 on your Ubuntu Maverick system, but it won't go into more advanced Samba topics. At first I wanted this to be a full step-by-step guide, however I can't find the time to complete it as such (I started writing when Maverick was in beta). I welcome comments adding more details and I hope everyone will be able to follow this howto.

Let's start by updating the system.

$ sudo apt-get update

Next add a PPA which includes a more recent Bind 9 version. I believe this is mainly needed so your Windows clients can send DNS updates to the domain controller, but I can't say I thoroughly tested with the Ubuntu Maverick distributed version.

Personally I used bind9 from Hauke Lampe's PPA (BIND 9 Updates : Hauke Lampe).

Install samba4 and bind9:

$ sudo apt-get install samba4 samba4-clients bind9

Move existing smb.conf:

$ sudo mv /etc/samba/smb.conf{,.old}

Create a samba 4 config and provision the database:

$ sudo LD_PRELOAD=/usr/lib/libdcerpc.so.0.0.1 /usr/share/samba/setup/provision --realm=samdom.example.com --domain=SAMDOM --adminpass=SOMEPASSWORD --server-role='domain controller'

You might be wondering what this LD_PRELOAD is about, well it's needed because some stuff is missing the link to the dcerpc library.

Now we want to start samba, there's another issue ahead. The samba4 init script doesn't check for the existence of the samba directory in /var/run, so let's add that ourselves.

# /etc/init.d/samba4
...
  log_daemon_msg "Starting Samba 4 daemon" "samba"

  if [ ! -d $(dirname $SAMBAPID) ]; then
   mkdir -p $(dirname $SAMBAPID)
  fi

  if !...

We're still not there yet... Remember the missing library link? It will also return while running Samba, so let's work around it by creating local versions of the samba programs that will load the library:

Create /usr/local/sbin/samba:

#!/bin/sh
LD_PRELOAD=/usr/lib/libdcerpc.so.0.0.1 /usr/sbin/$(basename $0)

Now symlink samba_dnsupdate and samba_spnupdate to the same file:

$ sudo ln -s /usr/local/sbin/samba{,_dnsupdate}
$ sudo ln -s /usr/local/sbin/samba{,_spnupdate}

Now start samba:

$ sudo /etc/init.d/samba4 start

Let's do a quick test if it's working:

$ smbclient -UAdministrator -Llocalhost
Password for [SAMDOM\Administrator]:

 Sharename       Type       Comment
 ---------       ----       -------
 netlogon        Disk       
 sysvol          Disk       
 IPC$            IPC        IPC Service (Samba 4.0.0alpha12-GIT-UNKNOWN)
 ADMIN$          Disk       DISK Service (Samba 4.0.0alpha12-GIT-UNKNOWN)
REWRITE: list servers not implemented

Seems to be working!

Now let's get DNS working too. Start by editing named.conf.local:

// /etc/bind/named.conf.local
...
//include "/etc/bind/zones.rfc1918";

include "/var/lib/samba/private/named.conf";

Thought we were done? Think again! AppArmor is protecting our samba4 files from bind, I'd rather have bind read them though...

# /etc/apparmor.d/usr.sbin.named
...
/var/lib/samba/private/* rw,
/var/lib/samba/private/dns/* rw,
}

Reload AppArmor profiles and restart bind:

$ sudo /etc/init.d/apparmor reload
$ sudo /etc/init.d/bind9 restart

Bind should now start without any issues. Next is to actually use bind for DNS:

# /etc/resolv.conf
nameserver 127.0.0.1

You can verify it's working by querying dns for kerberos:

$ host -t SRV _kerberos._udp.samdom.example.com

This should return an SRV record, if not, something's broken!

Now let's move the Kerberos config into place:

$ sudo cp /var/lib/samba/private/krb5.conf /etc/

You can verify it's working by installing krb5-user and doing a kinit Administrator, but since Kerberos comes out of the box with samba, I'm assuming it's working (it always did for me).

If you chose to add a PPA with a recent Bind version, you can enable Kerberized DNS updates by pointing named to the correct principal and keytab. More details on this can be found on the Samba 4 howto, I will add my own details here later.



You should now be able to administer your Samba 4 domain controller using the microsoft utilities for windows server management, the Samba net tool or direct LDAP queries.

Updates

dec 8 2010, 22:56

Added missing apparmor policy changes

Rsync and remote sudo

Running rsync with superuser privileges can be hard at times, but here's an easy solution works on Ubuntu 10.04 (some other solutions failed to work):

$  echo "password" | ssh sudo -S -v
$ sudo rsync -a -e ssh --rsync-path="sudo rsync"

The first line will touch the timestamp for sudo, the second line will really sync. Keep in mind that this doesn't take care of credentials for ssh, so you will need to take care of this using keys, agents or some external authentication mechanism like Kerberos.