Apache allow & deny rules parsed differently on different RHEL versions? - apache

Question

I have 6 machines: 3 running RHEL 3 (Taroon Update 9) and 3 other running RHEL 5.6 (Tikanga).
They all share a NFS volume containing
an Apache 2.2.4 installation
that Apache's configuration files
the PHP scripts and other content served by that Apache
On each machine, that shared Apache is started with the "-D $hostname" option to distinguish from the Apache instances running on the other machines. (Where $hostname is the hostname of the machine).
There is a load balancer (another Apache) in front of these 6 machines, balancing the requests between them.
The problem:
I've placed a .htaccess file in a directory containing these rules:
order deny,allow
deny from all
allow from my.very.own.ip
(I've tried the same rules in the configuration file between , with the same result)
Any request from any IP other than my.very.own.ip is denied by all 6 Apaches.
Requests from my.very.own.ip that hit the first 3 Apaches (running on RHEL 3) are accepted, which is normal.
Requests from my.very.own.ip that hit the last 3 Apaches (running on RHEL 5.6) are denied (HTTP 403, client denied by server configuration), which is not normal.
I've ran a strace on all the Apache servers (and their forked children) and this is how they look like:
- on a "good" Apache with request coming from my.very.own.ip
19553 read(7, "GET /my/website"..., 8000) = 1761
19553 gettimeofday({1343736878, 168708}, NULL) = 0
19553 gettimeofday({1343736878, 168787}, NULL) = 0
19553 gettimeofday({1343736878, 168835}, NULL) = 0
19553 stat64("/shark/apps/apache1/conf/www/maps/stationlist.txt", {st_mode=S_IFREG|0644, st_size=5557, ...}) = 0
19553 stat64("/shark/apps/apache1/conf/somedir/stationkidsurls.txt", {st_mode=S_IFREG|0644, st_size=6200, ...}) = 0
19553 stat64("/shark/www_docs/my/website/php/script.php", {st_mode=S_IFREG|0644, st_size=2449, ...}) = 0
19553 open("/shark/www_docs/.htaccess", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory)
19553 open("/shark/www_docs/my/.htaccess", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory)
19553 open("/shark/www_docs/my/website/.htaccess", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory)
19553 open("/shark/www_docs/my/website/php/.htaccess", O_RDONLY|O_LARGEFILE) = 10
19553 fstat64(10, {st_mode=S_IFREG|0644, st_size=51, ...}) = 0
19553 read(10, " order deny,allow\n deny f"..., 4096) = 51
19553 read(10, "", 4096) = 0
19553 close(10) = 0
19553 open("/shark/www_docs/my/website/php/script.php/.htaccess", O_RDONLY|O_LARGEFILE) = -1 ENOTDIR (Not a directory)
19553 getpid() = 19553
19553 setitimer(ITIMER_PROF, {it_interval={0, 0}, it_value={60, 0}}, NULL) = 0
19553 rt_sigaction(SIGPROF, {0x1280014, [PROF], SA_RESTORER|SA_RESTART, 0x3c10d8}, {0x1280014, [PROF], SA_RESTORER|SA_RESTART, 0x3c10d8}, 8) = 0
19553 rt_sigprocmask(SIG_UNBLOCK, [PROF], NULL, 8) = 0
19553 getcwd("/", 4095) = 2
19553 chdir("/shark/www_docs/my/website/php") = 0
- on a "bad" Apache with request coming from my.very.own.ip
1723 read(9, "GET /my/website"..., 8000) = 1761
1723 gettimeofday({1343736621, 548677}, NULL) = 0
1723 gettimeofday({1343736621, 548735}, NULL) = 0
1723 gettimeofday({1343736621, 548771}, NULL) = 0
1723 stat64("/shark/apps/apache1/conf/www/maps/stationlist.txt", {st_mode=S_IFREG|0644, st_size=5557, ...}) = 0
1723 stat64("/shark/apps/apache1/conf/somedir/stationkidsurls.txt", {st_mode=S_IFREG|0644, st_size=6200, ...}) = 0
1723 stat64("/shark/www_docs/my/website/php/script.php", {st_mode=S_IFREG|0644, st_size=2449, ...}) = 0
1723 open("/shark/www_docs/.htaccess", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory)
1723 open("/shark/www_docs/my/.htaccess", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory)
1723 open("/shark/www_docs/my/website/.htaccess", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory)
1723 open("/shark/www_docs/my/website/php/.htaccess", O_RDONLY|O_LARGEFILE) = 12
1723 fstat64(12, {st_mode=S_IFREG|0644, st_size=51, ...}) = 0
1723 read(12, " order deny,allow\n deny f"..., 4096) = 51
1723 read(12, "", 4096) = 0
1723 close(12) = 0
1723 open("/shark/www_docs/my/website/php/script.php/.htaccess", O_RDONLY|O_LARGEFILE) = -1 ENOTDIR (Not a directory)
1723 gettimeofday({1343736621, 550606}, NULL) = 0
1723 write(10, "[Tue Jul 31 08:10:21 2012] [erro"..., 159) = 159
729 <... read resumed> "[Tue Jul 31 08:10:21 2012] [erro"..., 65536) = 159
729 gettimeofday({1343736621, 550743}, NULL) = 0
729 gettimeofday({1343736621, 550786}, NULL) = 0
What do you think?
The only difference between these machines in the RHEL version. That may also mean that the NFS share ( /shark ) is mounted differently...
I've modified the .htaccess an changed the allow,deny rule with a Rewrite (requests not coming from my.very.own.ip are redirected to somewhere else). But... I'm still wondering why the same rules behave differently on different machines (same Apache, same configuration files).
Thank you!