+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
+ "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<html>
+ <head>
+ <title>Petter Reinholdtsen: entries from August 2010</title>
+ <link rel="stylesheet" type="text/css" media="screen" href="http://people.skolelinux.org/pere/blog/style.css">
+ <link rel="alternate" title="RSS Feed" href="08.rss" type="application/rss+xml">
+ </head>
+ <body>
+<!-- XML FEED -->
+
+ <div class="title">
+ <h1>
+ <a href="http://people.skolelinux.org/pere/blog/">Petter Reinholdtsen</a>
+
+ </h1>
+
+ </div>
+
+ <p>Entries from August 2010.</p>
+
+
+<div class="entry">
+ <div class="title">
+ <a href="http://people.skolelinux.org/pere/blog/Debian_Edu_roaming_workstation___at_the_university_of_Oslo.html">Debian Edu roaming workstation - at the university of Oslo</a>
+ </div>
+ <div class="date">
+ 2010-08-03 23:30
+ </div>
+
+ <div class="body">
+
+<p>The new roaming workstation profile in Debian Edu/Squeeze is fairly
+similar to the laptop setup am I working on using Ubuntu for the
+University of Oslo, and just for the heck of it, I tested today how
+hard it would be to integrate that profile into the university
+infrastructure. In this case, it is the university LDAP server,
+Active Directory Kerberos server and SMB mounting from the Netapp file
+servers.</p>
+
+<p>I was pleasantly surprised that the only three files needed to be
+changed (/etc/sssd/sssd.conf, /etc/ldap.conf and
+/etc/mklocaluser.d/20-debian-edu-config) and one file had to be added
+(/usr/share/perl5/Debian/Edu_Local.pm), to get the client working.
+Most of the changes were to get the client to use the university LDAP
+for NSS and Kerberos server for PAM, but one was to change a hard
+coded DNS domain name in the mklocaluser hook from .intern to
+.uio.no.</p>
+
+<p>This testing was so encouraging, that I went ahead and adjusted the
+Debian Edu scripts and setup in subversion to centralise the roaming
+workstation setup a bit more and avoid the hardcoded DNS domain name,
+so that when I test this tomorrow, I expect to get away with modifying
+only /etc/sssd/sssd.conf and /etc/ldap.conf to get it to use the
+university servers.</p>
+
+<p>My goal is to get the clients to have no hardcoded settings and
+fetch all their initial setup during installation and first boot, to
+allow them to be inserted also into environments where the default
+setup in Debian Edu has been changed or as with the university, where
+the environment is different but provides the protocols Debian Edu
+uses.</p>
+
+ </div>
+ <div class="tags">
+
+
+
+ Tags: <a href="http://people.skolelinux.org/pere/blog/tags/debian edu">debian edu</a>, <a href="http://people.skolelinux.org/pere/blog/tags/english">english</a>, <a href="http://people.skolelinux.org/pere/blog/tags/nuug">nuug</a>.
+
+ </div>
+</div>
+ <div class="padding"></div>
+
+<div class="entry">
+ <div class="title">
+ <a href="http://people.skolelinux.org/pere/blog/Autodetecting_Client_setup_for_roaming_workstations_in_Debian_Edu.html">Autodetecting Client setup for roaming workstations in Debian Edu</a>
+ </div>
+ <div class="date">
+ 2010-08-07 14:45
+ </div>
+
+ <div class="body">
+
+<p>A few days ago, I
+<a href="http://people.skolelinux.org/pere/blog/Debian_Edu_roaming_workstation___at_the_university_of_Oslo.html">tried
+to install</a> a Roaming workation profile from Debian Edu/Squeeze
+while on the university network here at the University of Oslo, and
+noticed how much had to change to get it operational using the
+university infrastructure. It was fairly easy, but it occured to me
+that Debian Edu would improve a lot if I could get the client to
+connect without any changes at all, and thus let the client configure
+itself during installation and first boot to use the infrastructure
+around it. Now I am a huge step further along that road.</p>
+
+<p>With our current squeeze-test packages, I can select the roaming
+workstation profile and get a working laptop connecting to the
+university LDAP server for user and group and our active directory
+servers for Kerberos authentication. All this without any
+configuration at all during installation. My users home directory got
+a bookmark in the KDE menu to mount it via SMB, with the correct URL.
+In short, openldap and sssd is correctly configured. In addition to
+this, the client look for http://wpad/wpad.dat to configure a web
+proxy, and when it fail to find it no proxy settings are stored in
+/etc/environment and /etc/apt/apt.conf. Iceweasel and KDE is
+configured to look for the same wpad configuration and also do not use
+a proxy when at the university network. If the machine is moved to a
+network with such wpad setup, it would automatically use it when DHCP
+gave it a IP address.</p>
+
+<p>The LDAP server is located using DNS, by first looking for the DNS
+entry ldap.$domain. If this do not exist, it look for the
+_ldap._tcp.$domain SRV records and use the first one as the LDAP
+server. Next, it connects to the LDAP server and search all
+namingContexts entries for posixAccount or posixGroup objects, and
+pick the first one as the LDAP base. For Kerberos, a similar
+algorithm is used to locate the LDAP server, and the realm is the
+uppercase version of $domain.</p>
+
+<p>So, what is not working, you might ask. SMB mounting my home
+directory do not work. No idea why, but suspected the incorrect
+Kerberos settings in /etc/krb5.conf and /etc/samba/smb.conf might be
+the cause. These are not properly configured during installation, and
+had to be hand-edited to get the correct Kerberos realm and server,
+but SMB mounting still do not work. :(</p>
+
+<p>With this automatic configuration in place, I expect a Debian Edu
+roaming profile installation would be able to automatically detect and
+connect to any site using LDAP and Kerberos for NSS directory and PAM
+authentication. It should also work out of the box in a Active
+Directory environment providing posixAccount and posixGroup objects
+with UID and GID values.</p>
+
+<p>If you want to help out with implementing these things for Debian
+Edu, please contact us on debian-edu@lists.debian.org.</p>
+
+ </div>
+ <div class="tags">
+
+
+
+ Tags: <a href="http://people.skolelinux.org/pere/blog/tags/debian edu">debian edu</a>, <a href="http://people.skolelinux.org/pere/blog/tags/english">english</a>, <a href="http://people.skolelinux.org/pere/blog/tags/nuug">nuug</a>.
+
+ </div>
+</div>
+ <div class="padding"></div>
+
+<div class="entry">
+ <div class="title">
+ <a href="http://people.skolelinux.org/pere/blog/Testing_if_a_file_system_can_be_used_for_home_directories___.html">Testing if a file system can be used for home directories...</a>
+ </div>
+ <div class="date">
+ 2010-08-08 21:20
+ </div>
+
+ <div class="body">
+
+<p>A few years ago, I was involved in a project planning to use
+Windows file servers as home directory servers for Debian
+Edu/Skolelinux machines. This was thought to be no problem, as the
+access would be through the SMB network file system protocol, and we
+knew other sites used SMB with unix and samba as the file server to
+mount home directories without any problems. But, after months of
+struggling, we had to conclude that our goal was impossible.</p>
+
+<p>The reason is simply that while SMB can be used for home
+directories when the file server is Samba running on Unix, this only
+work because of Samba have some extensions and the fact that the
+underlying file system is a unix file system. When using a Windows
+file server, the underlying file system do not have POSIX semantics,
+and several programs will fail if the users home directory where they
+want to store their configuration lack POSIX semantics.</p>
+
+<p>As part of this work, I wrote a small C program I want to share
+with you all, to replicate a few of the problematic applications (like
+OpenOffice.org and GCompris) and see if the file system was working as
+it should. If you find yourself in spooky file system land, it might
+help you find your way out again. This is the fs-test.c source:</p>
+
+<pre>
+/*
+ * Some tests to check the file system sematics. Used to verify that
+ * CIFS from a windows server do not work properly as a linux home
+ * directory.
+ * License: GPL v2 or later
+ *
+ * needs libsqlite3-dev and build-essential installed
+ * compile with: gcc -Wall -lsqlite3 -DTEST_SQLITE fs-test.c -o fs-test
+*/
+
+#define _FILE_OFFSET_BITS 64
+#define _LARGEFILE_SOURCE 1
+#define _LARGEFILE64_SOURCE 1
+
+#define _GNU_SOURCE /* for asprintf() */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <sys/file.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#ifdef TEST_SQLITE
+/*
+ * Test sqlite open, as done by gcompris require the libsqlite3-dev
+ * package and linking with -lsqlite3. A more low level test is
+ * below.
+ * See also <URL: http://www.sqlite.org./faq.html#q5 >.
+ */
+#include <sqlite3.h>
+#define CREATE_TABLE_USERS \
+ "CREATE TABLE users (user_id INT UNIQUE, login TEXT, lastname TEXT, firstname TEXT, birthdate TEXT, class_id INT ); "
+int test_sqlite_open(void) {
+ char *zErrMsg;
+ char *name = "testsqlite.db";
+ sqlite3 *db=NULL;
+ unlink(name);
+ int rc = sqlite3_open(name, &db);
+ if( rc ){
+ printf("error: sqlite open of %s failed: %s\n", name, sqlite3_errmsg(db));
+ sqlite3_close(db);
+ return -1;
+ }
+
+ /* create tables */
+ rc = sqlite3_exec(db,CREATE_TABLE_USERS, NULL, 0, &zErrMsg);
+ if( rc != SQLITE_OK ){
+ printf("error: sqlite table create failed: %s\n", zErrMsg);
+ sqlite3_close(db);
+ return -1;
+ }
+ printf("info: sqlite worked\n");
+ sqlite3_close(db);
+ return 0;
+}
+#endif /* TEST_SQLITE */
+
+/*
+ * Demonstrate locking issue found in gcompris using sqlite3. This
+ * work with ext3, but not with cifs server on Windows 2003. This is
+ * done in the sqlite3 library.
+ * See also
+ * <URL:http://www.cygwin.com/ml/cygwin/2001-08/msg00854.html> and the
+ * POSIX specification
+ * <URL:http://www.opengroup.org/onlinepubs/009695399/functions/fcntl.html>.
+ */
+int test_gcompris_locking(void) {
+ struct flock fl;
+ char *name = "testsqlite.db";
+ unlink(name);
+ int fd = open(name, O_RDWR|O_CREAT|O_LARGEFILE, 0644);
+ printf("info: testing fcntl locking\n");
+
+ fl.l_whence = SEEK_SET;
+ fl.l_pid = getpid();
+ printf(" Read-locking 1 byte from 1073741824");
+ fl.l_start = 1073741824;
+ fl.l_len = 1;
+ fl.l_type = F_RDLCK;
+ if (0 != fcntl(fd, F_SETLK, &fl) ) printf(" - error!\n"); else printf("\n");
+
+ printf(" Read-locking 510 byte from 1073741826");
+ fl.l_start = 1073741826;
+ fl.l_len = 510;
+ fl.l_type = F_RDLCK;
+ if (0 != fcntl(fd, F_SETLK, &fl) ) printf(" - error!\n"); else printf("\n");
+
+ printf(" Unlocking 1 byte from 1073741824");
+ fl.l_start = 1073741824;
+ fl.l_len = 1;
+ fl.l_type = F_UNLCK;
+ if (0 != fcntl(fd, F_SETLK, &fl) ) printf(" - error!\n"); else printf("\n");
+
+ printf(" Write-locking 1 byte from 1073741824");
+ fl.l_start = 1073741824;
+ fl.l_len = 1;
+ fl.l_type = F_WRLCK;
+ if (0 != fcntl(fd, F_SETLK, &fl) ) printf(" - error!\n"); else printf("\n");
+
+ printf(" Write-locking 510 byte from 1073741826");
+ fl.l_start = 1073741826;
+ fl.l_len = 510;
+ if (0 != fcntl(fd, F_SETLK, &fl) ) printf(" - error!\n"); else printf("\n");
+
+ printf(" Unlocking 2 byte from 1073741824");
+ fl.l_start = 1073741824;
+ fl.l_len = 2;
+ fl.l_type = F_UNLCK;
+ if (0 != fcntl(fd, F_SETLK, &fl) ) printf(" - error!\n"); else printf("\n");
+
+ close(fd);
+ return 0;
+}
+
+/*
+ * Test if permissions of freshly created directories allow entries
+ * below them. This was a problem with OpenOffice.org and gcompris.
+ * Mounting with option 'sync' seem to solve this problem while
+ * slowing down file operations.
+ */
+int test_subdirectory_creation(void) {
+#define LEVELS 5
+ char *path = strdup("test");
+ char *dirs[LEVELS];
+ int level;
+ printf("info: testing subdirectory creation\n");
+ for (level = 0; level < LEVELS; level++) {
+ char *newpath = NULL;
+ if (-1 == mkdir(path, 0777)) {
+ printf(" error: Unable to create directory '%s': %s\n",
+ path, strerror(errno));
+ break;
+ }
+ asprintf(&newpath, "%s/%s", path, "test");
+ free(path);
+ path = newpath;
+ }
+ return 0;
+}
+
+/*
+ * Test if symlinks can be created. This was a problem detected with
+ * KDE.
+ */
+int test_symlinks(void) {
+ printf("info: testing symlink creation\n");
+ unlink("symlink");
+ if (-1 == symlink("file", "symlink"))
+ printf(" error: Unable to create symlink\n");
+ return 0;
+}
+
+int main(int argc, char **argv) {
+ printf("Testing POSIX/Unix sematics on file system\n");
+ test_symlinks();
+ test_subdirectory_creation();
+#ifdef TEST_SQLITE
+ test_sqlite_open();
+#endif /* TEST_SQLITE */
+ test_gcompris_locking();
+ return 0;
+}
+</pre>
+
+<p>When everything is working, it should print something like
+this:</p>
+
+<pre>
+Testing POSIX/Unix sematics on file system
+info: testing symlink creation
+info: testing subdirectory creation
+info: sqlite worked
+info: testing fcntl locking
+ Read-locking 1 byte from 1073741824
+ Read-locking 510 byte from 1073741826
+ Unlocking 1 byte from 1073741824
+ Write-locking 1 byte from 1073741824
+ Write-locking 510 byte from 1073741826
+ Unlocking 2 byte from 1073741824
+</pre>
+
+<p>I do not remember the exact details of the problems we saw, but one
+of them was with locking, where if I remember correctly, POSIX allow a
+read-only lock to be upgraded to a read-write lock without unlocking
+the read-only lock (while Windows do not). Another was a bug in the
+CIFS/SMB client implementation in the Linux kernel where directory
+meta information would be wrong for a fraction of a second, making
+OpenOffice.org fail to create its deep directory tree because it was
+not allowed to create files in its freshly created directory.</p>
+
+<p>Anyway, here is a nice tool for your tool box, might you never need
+it. :)</p>
+
+ </div>
+ <div class="tags">
+
+
+
+ Tags: <a href="http://people.skolelinux.org/pere/blog/tags/debian edu">debian edu</a>, <a href="http://people.skolelinux.org/pere/blog/tags/english">english</a>, <a href="http://people.skolelinux.org/pere/blog/tags/nuug">nuug</a>.
+
+ </div>
+</div>
+ <div class="padding"></div>
+
+ <p style="text-align: right;"><a href="08.rss"><img src="http://people.skolelinux.org/pere/blog/xml.gif" alt="RSS Feed" width="36" height="14"></a></p>
+
+
+
+<div id="sidebar">
+
+<h2>Archive</h2>
+<ul>
+
+<li>2010
+<ul>
+
+<li><a href="http://people.skolelinux.org/pere/blog/archive/2010/01/">January (2)</a></li>
+
+<li><a href="http://people.skolelinux.org/pere/blog/archive/2010/02/">February (1)</a></li>
+
+<li><a href="http://people.skolelinux.org/pere/blog/archive/2010/03/">March (3)</a></li>
+
+<li><a href="http://people.skolelinux.org/pere/blog/archive/2010/04/">April (3)</a></li>
+
+<li><a href="http://people.skolelinux.org/pere/blog/archive/2010/05/">May (9)</a></li>
+
+<li><a href="http://people.skolelinux.org/pere/blog/archive/2010/06/">June (14)</a></li>
+
+<li><a href="http://people.skolelinux.org/pere/blog/archive/2010/07/">July (12)</a></li>
+
+<li><a href="http://people.skolelinux.org/pere/blog/archive/2010/08/">August (3)</a></li>
+
+</ul></li>
+
+<li>2009
+<ul>
+
+<li><a href="http://people.skolelinux.org/pere/blog/archive/2009/01/">January (8)</a></li>
+
+<li><a href="http://people.skolelinux.org/pere/blog/archive/2009/02/">February (8)</a></li>
+
+<li><a href="http://people.skolelinux.org/pere/blog/archive/2009/03/">March (12)</a></li>
+
+<li><a href="http://people.skolelinux.org/pere/blog/archive/2009/04/">April (10)</a></li>
+
+<li><a href="http://people.skolelinux.org/pere/blog/archive/2009/05/">May (9)</a></li>
+
+<li><a href="http://people.skolelinux.org/pere/blog/archive/2009/06/">June (3)</a></li>
+
+<li><a href="http://people.skolelinux.org/pere/blog/archive/2009/07/">July (4)</a></li>
+
+<li><a href="http://people.skolelinux.org/pere/blog/archive/2009/08/">August (3)</a></li>
+
+<li><a href="http://people.skolelinux.org/pere/blog/archive/2009/09/">September (1)</a></li>
+
+<li><a href="http://people.skolelinux.org/pere/blog/archive/2009/10/">October (2)</a></li>
+
+<li><a href="http://people.skolelinux.org/pere/blog/archive/2009/11/">November (3)</a></li>
+
+<li><a href="http://people.skolelinux.org/pere/blog/archive/2009/12/">December (3)</a></li>
+
+</ul></li>
+
+<li>2008
+<ul>
+
+<li><a href="http://people.skolelinux.org/pere/blog/archive/2008/11/">November (5)</a></li>
+
+<li><a href="http://people.skolelinux.org/pere/blog/archive/2008/12/">December (7)</a></li>
+
+</ul></li>
+
+</ul>
+
+
+
+<h2>Tags</h2>
+<ul>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/3d-printer">3d-printer (11)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/amiga">amiga (1)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/aros">aros (1)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/bootsystem">bootsystem (10)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/debian">debian (35)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/debian edu">debian edu (39)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/english">english (54)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/fiksgatami">fiksgatami (1)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/fildeling">fildeling (8)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/kart">kart (3)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/ldap">ldap (8)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/lenker">lenker (1)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/ltsp">ltsp (1)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/multimedia">multimedia (5)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/norsk">norsk (71)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/nuug">nuug (91)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/opphavsrett">opphavsrett (14)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/personvern">personvern (14)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/reprap">reprap (10)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/rss">rss (1)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/sikkerhet">sikkerhet (10)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/sitesummary">sitesummary (3)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/standard">standard (13)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/stavekontroll">stavekontroll (1)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/video">video (10)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/vitenskap">vitenskap (1)</a></li>
+
+ <li><a href="http://people.skolelinux.org/pere/blog/tags/web">web (7)</a></li>
+
+</ul>
+
+</div>
+</body>
+</html>
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