Apache HTTP Server Version 2.0
Apache HTTP Server Version 2.0
Available Languages: en
This document supplements the mod_rewrite
reference documentation.
It describes how one can use Apache's mod_rewrite
to solve typical URL-based problems with which webmasters are
commonly confronted. We give detailed descriptions on how to
solve each problem by configuring URL rewriting rulesets.
[PT] flag if
using mod_alias and
mod_userdir, etc. Or rewriting a ruleset
to work in .htaccess context instead
of per-server context. Always try to understand what a
particular ruleset really does before you use it; this
avoids many problems.
Web Cluster with Consistent URL Space Structured Homedirs Filesystem Reorganization Redirect Failing URLs to Another Web Server Archive Access Multiplexer Content Handling Access Restriction
We want to create a homogeneous and consistent URL layout across all WWW servers on an Intranet web cluster, i.e., all URLs (by definition server-local and thus server-dependent!) become server independent! What we want is to give the WWW namespace a single consistent layout: no URL should refer to any particular target server. The cluster itself should connect users automatically to a physical target host as needed, invisibly.
First, the knowledge of the target servers comes from (distributed) external maps which contain information on where our users, groups, and entities reside. They have the form:
user1 server_of_user1 user2 server_of_user2 : :
We put them into files map.xxx-to-host.
Second we need to instruct all servers to redirect URLs
of the forms:
/u/user/anypath /g/group/anypath /e/entity/anypath
to
http://physical-host/u/user/anypath http://physical-host/g/group/anypath http://physical-host/e/entity/anypath
when any URL path need not be valid on every server. The following ruleset does this for us with the help of the map files (assuming that server0 is a default server which will be used if a user has no entry in the map):
RewriteEngine on
RewriteMap user-to-host txt:/path/to/map.user-to-host
RewriteMap group-to-host txt:/path/to/map.group-to-host
RewriteMap entity-to-host txt:/path/to/map.entity-to-host
RewriteRule ^/u/([^/]+)/?(.*) http://${user-to-host:$1|server0}/u/$1/$2
RewriteRule ^/g/([^/]+)/?(.*) http://${group-to-host:$1|server0}/g/$1/$2
RewriteRule ^/e/([^/]+)/?(.*) http://${entity-to-host:$1|server0}/e/$1/$2
RewriteRule ^/([uge])/([^/]+)/?$ /$1/$2/.www/
RewriteRule ^/([uge])/([^/]+)/([^.]+.+) /$1/$2/.www/$3\
Some sites with thousands of users use a
structured homedir layout, i.e. each homedir is in a
subdirectory which begins (for instance) with the first
character of the username. So, /~foo/anypath
is /home/f/foo/.www/anypath
while /~bar/anypath is
/home/b/bar/.www/anypath.
We use the following ruleset to expand the tilde URLs into the above layout.
RewriteEngine on RewriteRule ^/~(([a-z])[a-z0-9]+)(.*) /home/$2/$1/.www$3
This really is a hardcore example: a killer application
which heavily uses per-directory
RewriteRules to get a smooth look and feel
on the Web while its data structure is never touched or
adjusted. Background: net.sw is
my archive of freely available Unix software packages,
which I started to collect in 1992. It is both my hobby
and job to do this, because while I'm studying computer
science I have also worked for many years as a system and
network administrator in my spare time. Every week I need
some sort of software so I created a deep hierarchy of
directories where I stored the packages:
drwxrwxr-x 2 netsw users 512 Aug 3 18:39 Audio/ drwxrwxr-x 2 netsw users 512 Jul 9 14:37 Benchmark/ drwxrwxr-x 12 netsw users 512 Jul 9 00:34 Crypto/ drwxrwxr-x 5 netsw users 512 Jul 9 00:41 Database/ drwxrwxr-x 4 netsw users 512 Jul 30 19:25 Dicts/ drwxrwxr-x 10 netsw users 512 Jul 9 01:54 Graphic/ drwxrwxr-x 5 netsw users 512 Jul 9 01:58 Hackers/ drwxrwxr-x 8 netsw users 512 Jul 9 03:19 InfoSys/ drwxrwxr-x 3 netsw users 512 Jul 9 03:21 Math/ drwxrwxr-x 3 netsw users 512 Jul 9 03:24 Misc/ drwxrwxr-x 9 netsw users 512 Aug 1 16:33 Network/ drwxrwxr-x 2 netsw users 512 Jul 9 05:53 Office/ drwxrwxr-x 7 netsw users 512 Jul 9 09:24 SoftEng/ drwxrwxr-x 7 netsw users 512 Jul 9 12:17 System/ drwxrwxr-x 12 netsw users 512 Aug 3 20:15 Typesetting/ drwxrwxr-x 10 netsw users 512 Jul 9 14:08 X11/
In July 1996 I decided to make this archive public to the world via a nice Web interface. "Nice" means that I wanted to offer an interface where you can browse directly through the archive hierarchy. And "nice" means that I didn't want to change anything inside this hierarchy - not even by putting some CGI scripts at the top of it. Why? Because the above structure should later be accessible via FTP as well, and I didn't want any Web or CGI stuff mixed in there.
The solution has two parts: The first is a set of CGI
scripts which create all the pages at all directory
levels on-the-fly. I put them under
/e/netsw/.www/ as follows:
-rw-r--r-- 1 netsw users 1318 Aug 1 18:10 .wwwacl drwxr-xr-x 18 netsw users 512 Aug 5 15:51 DATA/ -rw-rw-rw- 1 netsw users 372982 Aug 5 16:35 LOGFILE -rw-r--r-- 1 netsw users 659 Aug 4 09:27 TODO -rw-r--r-- 1 netsw users 5697 Aug 1 18:01 netsw-about.html -rwxr-xr-x 1 netsw users 579 Aug 2 10:33 netsw-access.pl -rwxr-xr-x 1 netsw users 1532 Aug 1 17:35 netsw-changes.cgi -rwxr-xr-x 1 netsw users 2866 Aug 5 14:49 netsw-home.cgi drwxr-xr-x 2 netsw users 512 Jul 8 23:47 netsw-img/ -rwxr-xr-x 1 netsw users 24050 Aug 5 15:49 netsw-lsdir.cgi -rwxr-xr-x 1 netsw users 1589 Aug 3 18:43 netsw-search.cgi -rwxr-xr-x 1 netsw users 1885 Aug 1 17:41 netsw-tree.cgi -rw-r--r-- 1 netsw users 234 Jul 30 16:35 netsw-unlimit.lst
The DATA/ subdirectory holds the above
directory structure, i.e. the real
net.sw stuff, and gets
automatically updated via rdist from time to
time. The second part of the problem remains: how to link
these two structures together into one smooth-looking URL
tree? We want to hide the DATA/ directory
from the user while running the appropriate CGI scripts
for the various URLs. Here is the solution: first I put
the following into the per-directory configuration file
in the DocumentRoot
of the server to rewrite the public URL path
/net.sw/ to the internal path
/e/netsw:
RewriteRule ^net.sw$ net.sw/ [R] RewriteRule ^net.sw/(.*)$ e/netsw/$1
The first rule is for requests which miss the trailing
slash! The second rule does the real thing. And then
comes the killer configuration which stays in the
per-directory config file
/e/netsw/.www/.wwwacl:
Options ExecCGI FollowSymLinks Includes MultiViews RewriteEngine on # we are reached via /net.sw/ prefix RewriteBase /net.sw/ # first we rewrite the root dir to # the handling cgi script RewriteRule ^$ netsw-home.cgi [L] RewriteRule ^index\.html$ netsw-home.cgi [L] # strip out the subdirs when # the browser requests us from perdir pages RewriteRule ^.+/(netsw-[^/]+/.+)$ $1 [L] # and now break the rewriting for local files RewriteRule ^netsw-home\.cgi.* - [L] RewriteRule ^netsw-changes\.cgi.* - [L] RewriteRule ^netsw-search\.cgi.* - [L] RewriteRule ^netsw-tree\.cgi$ - [L] RewriteRule ^netsw-about\.html$ - [L] RewriteRule ^netsw-img/.*$ - [L] # anything else is a subdir which gets handled # by another cgi script RewriteRule !^netsw-lsdir\.cgi.* - [C] RewriteRule (.*) netsw-lsdir.cgi/$1
Some hints for interpretation:
L (last) flag and no
substitution field ('-') in the fourth part! (not) character and
the C (chain) flag at the first rule
in the last partA typical FAQ about URL rewriting is how to redirect
failing requests on webserver A to webserver B. Usually
this is done via ErrorDocument CGI scripts in Perl, but
there is also a mod_rewrite solution.
But note that this performs more poorly than using an
ErrorDocument
CGI script!
The first solution has the best performance but less flexibility, and is less safe:
RewriteEngine on
RewriteCond /your/docroot/%{REQUEST_FILENAME} !-f
RewriteRule ^(.+) http://webserverB.dom/$1
The problem here is that this will only work for pages
inside the DocumentRoot. While you can add more
Conditions (for instance to also handle homedirs, etc.)
there is a better variant:
RewriteEngine on
RewriteCond %{REQUEST_URI} !-U
RewriteRule ^(.+) http://webserverB.dom/$1
This uses the URL look-ahead feature of mod_rewrite.
The result is that this will work for all types of URLs
and is safe. But it does have a performance impact on
the web server, because for every request there is one
more internal subrequest. So, if your web server runs on a
powerful CPU, use this one. If it is a slow machine, use
the first approach or better an ErrorDocument CGI script.
Do you know the great CPAN (Comprehensive Perl Archive
Network) under http://www.perl.com/CPAN?
CPAN automatically redirects browsers to one of many FTP
servers around the world (generally one near the requesting
client); each server carries a full CPAN mirror. This is
effectively an FTP access multiplexing service.
CPAN runs via CGI scripts, but how could a similar approach
be implemented via mod_rewrite?
First we notice that as of version 3.0.0,
mod_rewrite can
also use the "ftp:" scheme on redirects.
And second, the location approximation can be done by a
RewriteMap
over the top-level domain of the client.
With a tricky chained ruleset we can use this top-level
domain as a key to our multiplexing map.
RewriteEngine on
RewriteMap multiplex txt:/path/to/map.cxan
RewriteRule ^/CxAN/(.*) %{REMOTE_HOST}::$1 [C]
RewriteRule ^.+\.([a-zA-Z]+)::(.*)$ ${multiplex:$1|ftp.default.dom}$2 [R,L]
## ## map.cxan -- Multiplexing Map for CxAN ## de ftp://ftp.cxan.de/CxAN/ uk ftp://ftp.cxan.uk/CxAN/ com ftp://ftp.cxan.com/CxAN/ : ##EOF##
At least for important top-level pages it is sometimes necessary to provide the optimum of browser dependent content, i.e., one has to provide one version for current browsers, a different version for the Lynx and text-mode browsers, and another for other browsers.
We cannot use content negotiation because the browsers do
not provide their type in that form. Instead we have to
act on the HTTP header "User-Agent". The following config
does the following: If the HTTP header "User-Agent"
begins with "Mozilla/3", the page foo.html
is rewritten to foo.NS.html and the
rewriting stops. If the browser is "Lynx" or "Mozilla" of
version 1 or 2, the URL becomes foo.20.html.
All other browsers receive page foo.32.html.
This is done with the following ruleset:
RewriteCond %{HTTP_USER_AGENT} ^Mozilla/3.*
RewriteRule ^foo\.html$ foo.NS.html [L]
RewriteCond %{HTTP_USER_AGENT} ^Lynx/.* [OR]
RewriteCond %{HTTP_USER_AGENT} ^Mozilla/[12].*
RewriteRule ^foo\.html$ foo.20.html [L]
RewriteRule ^foo\.html$ foo.32.html [L]
Assume there are nice web pages on remote hosts we want
to bring into our namespace. For FTP servers we would use
the mirror program which actually maintains an
explicit up-to-date copy of the remote data on the local
machine. For a web server we could use the program
webcopy which runs via HTTP. But both
techniques have a major drawback: The local copy is
always only as up-to-date as the last time we ran the program. It
would be much better if the mirror was not a static one we
have to establish explicitly. Instead we want a dynamic
mirror with data which gets updated automatically
as needed on the remote host(s).
To provide this feature we map the remote web page or even
the complete remote web area to our namespace by the use
of the Proxy Throughput feature
(flag [P]):
RewriteEngine on RewriteBase /~quux/ RewriteRule ^hotsheet/(.*)$ http://www.tstimpreso.com/hotsheet/$1 [P]
RewriteEngine on RewriteBase /~quux/ RewriteRule ^usa-news\.html$ http://www.quux-corp.com/news/index.html [P]
RewriteEngine on RewriteCond /mirror/of/remotesite/$1 -U RewriteRule ^http://www\.remotesite\.com/(.*)$ /mirror/of/remotesite/$1
This is a tricky way of virtually running a corporate
(external) Internet web server
(www.quux-corp.dom), while actually keeping
and maintaining its data on an (internal) Intranet web server
(www2.quux-corp.dom) which is protected by a
firewall. The trick is that the external web server retrieves
the requested data on-the-fly from the internal
one.
First, we must make sure that our firewall still protects the internal web server and only the external web server is allowed to retrieve data from it. On a packet-filtering firewall, for instance, we could configure a firewall ruleset like the following:
ALLOW Host www.quux-corp.dom Port >1024 --> Host www2.quux-corp.dom Port 80 DENY Host * Port * --> Host www2.quux-corp.dom Port 80
Just adjust it to your actual configuration syntax.
Now we can establish the mod_rewrite
rules which request the missing data in the background
through the proxy throughput feature:
RewriteRule ^/~([^/]+)/?(.*) /home/$1/.www/$2
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^/home/([^/]+)/.www/?(.*) http://www2.quux-corp.dom/~$1/pub/$2 [P]
Suppose we want to load balance the traffic to
www.foo.com over www[0-5].foo.com
(a total of 6 servers). How can this be done?
There are many possible solutions for this problem.
We will first discuss a common DNS-based method,
and then one based on mod_rewrite:
The simplest method for load-balancing is to use
DNS round-robin.
Here you just configure www[0-9].foo.com
as usual in your DNS with A (address) records, e.g.,
www0 IN A 1.2.3.1 www1 IN A 1.2.3.2 www2 IN A 1.2.3.3 www3 IN A 1.2.3.4 www4 IN A 1.2.3.5 www5 IN A 1.2.3.6
Then you additionally add the following entries:
www IN A 1.2.3.1 www IN A 1.2.3.2 www IN A 1.2.3.3 www IN A 1.2.3.4 www IN A 1.2.3.5
Now when www.foo.com gets
resolved, BIND gives out www0-www5
- but in a permutated (rotated) order every time.
This way the clients are spread over the various
servers. But notice that this is not a perfect load
balancing scheme, because DNS resolutions are
cached by clients and other nameservers, so
once a client has resolved www.foo.com
to a particular wwwN.foo.com, all its
subsequent requests will continue to go to the same
IP (and thus a single server), rather than being
distributed across the other available servers. But the
overall result is
okay because the requests are collectively
spread over the various web servers.
A sophisticated DNS-based method for
load-balancing is to use the program
lbnamed which can be found at
http://www.stanford.edu/~schemers/docs/lbnamed/lbnamed.html.
It is a Perl 5 program which, in conjunction with auxilliary
tools, provides real load-balancing via
DNS.
In this variant we use mod_rewrite
and its proxy throughput feature. First we dedicate
www0.foo.com to be actually
www.foo.com by using a single
www IN CNAME www0.foo.com.
entry in the DNS. Then we convert
www0.foo.com to a proxy-only server,
i.e., we configure this machine so all arriving URLs
are simply passed through its internal proxy to one of
the 5 other servers (www1-www5). To
accomplish this we first establish a ruleset which
contacts a load balancing script lb.pl
for all URLs.
RewriteEngine on
RewriteMap lb prg:/path/to/lb.pl
RewriteRule ^/(.+)$ ${lb:$1} [P,L]
Then we write lb.pl:
#!/path/to/perl
##
## lb.pl -- load balancing script
##
$| = 1;
$name = "www"; # the hostname base
$first = 1; # the first server (not 0 here, because 0 is myself)
$last = 5; # the last server in the round-robin
$domain = "foo.dom"; # the domainname
$cnt = 0;
while (<STDIN>) {
$cnt = (($cnt+1) % ($last+1-$first));
$server = sprintf("%s%d.%s", $name, $cnt+$first, $domain);
print "http://$server/$_";
}
##EOF##
www0.foo.com still is overloaded? The
answer is yes, it is overloaded, but with plain proxy
throughput requests, only! All SSI, CGI, ePerl, etc.
processing is handled done on the other machines.
For a complicated site, this may work well. The biggest
risk here is that www0 is now a single point of failure --
if it crashes, the other servers are inaccessible.There are more sophisticated solutions, as well. Cisco, F5, and several other companies sell hardware load balancers (typically used in pairs for redundancy), which offer sophisticated load balancing and auto-failover features. There are software packages which offer similar features on commodity hardware, as well. If you have enough money or need, check these out. The lb-l mailing list is a good place to research.
On the net there are many nifty CGI programs. But
their usage is usually boring, so a lot of webmasters
don't use them. Even Apache's Action handler feature for
MIME-types is only appropriate when the CGI programs
don't need special URLs (actually PATH_INFO
and QUERY_STRINGS) as their input. First,
let us configure a new file type with extension
.scgi (for secure CGI) which will be processed
by the popular cgiwrap program. The problem
here is that for instance if we use a Homogeneous URL Layout
(see above) a file inside the user homedirs might have a URL
like /u/user/foo/bar.scgi, but
cgiwrap needs URLs in the form
/~user/foo/bar.scgi/. The following rule
solves the problem:
RewriteRule ^/[uge]/([^/]+)/\.www/(.+)\.scgi(.*) ... ... /internal/cgi/user/cgiwrap/~$1/$2.scgi$3 [NS,T=application/x-http-cgi]
Or assume we have some more nifty programs:
wwwlog (which displays the
access.log for a URL subtree) and
wwwidx (which runs Glimpse on a URL
subtree). We have to provide the URL area to these
programs so they know which area they are really working with.
But usually this is complicated, because they may still be
requested by the alternate URL form, i.e., typically we would
run the swwidx program from within
/u/user/foo/ via hyperlink to
/internal/cgi/user/swwidx?i=/u/user/foo/
which is ugly, because we have to hard-code both the location of the area and the location of the CGI inside the hyperlink. When we have to reorganize, we spend a lot of time changing the various hyperlinks.
The solution here is to provide a special new URL format which automatically leads to the proper CGI invocation. We configure the following:
RewriteRule ^/([uge])/([^/]+)(/?.*)/\* /internal/cgi/user/wwwidx?i=/$1/$2$3/ RewriteRule ^/([uge])/([^/]+)(/?.*):log /internal/cgi/user/wwwlog?f=/$1/$2$3
Now the hyperlink to search at
/u/user/foo/ reads only
HREF="*"
which internally gets automatically transformed to
/internal/cgi/user/wwwidx?i=/u/user/foo/
The same approach leads to an invocation for the
access log CGI program when the hyperlink
:log gets used.
Here comes a really esoteric feature: Dynamically
generated but statically served pages, i.e., pages should be
delivered as pure static pages (read from the filesystem
and just passed through), but they have to be generated
dynamically by the web server if missing. This way you can
have CGI-generated pages which are statically served unless an
admin (or a cron job) removes the static contents. Then the
contents gets refreshed.
RewriteCond %{REQUEST_FILENAME} !-s
RewriteRule ^page\.html$ page.cgi [T=application/x-httpd-cgi,L]
Here a request for page.html leads to an
internal run of a corresponding page.cgi if
page.html is missing or has filesize
null. The trick here is that page.cgi is a
CGI script which (additionally to its STDOUT)
writes its output to the file page.html.
Once it has completed, the server sends out
page.html. When the webmaster wants to force
a refresh of the contents, he just removes
page.html (typically from cron).
Wouldn't it be nice, while creating a complex web page, if the web browser would automatically refresh the page every time we save a new version from within our editor? Impossible?
No! We just combine the MIME multipart feature, the
web server NPH feature, and the URL manipulation power of
mod_rewrite. First, we establish a new
URL feature: Adding just :refresh to any
URL causes the 'page' to be refreshed every time it is
updated on the filesystem.
RewriteRule ^(/[uge]/[^/]+/?.*):refresh /internal/cgi/apache/nph-refresh?f=$1
Now when we reference the URL
/u/foo/bar/page.html:refresh
this leads to the internal invocation of the URL
/internal/cgi/apache/nph-refresh?f=/u/foo/bar/page.html
The only missing part is the NPH-CGI script. Although one would usually say "left as an exercise to the reader" ;-) I will provide this, too.
#!/sw/bin/perl
##
## nph-refresh -- NPH/CGI script for auto refreshing pages
## Copyright (c) 1997 Ralf S. Engelschall, All Rights Reserved.
##
$| = 1;
# split the QUERY_STRING variable
@pairs = split(/&/, $ENV{'QUERY_STRING'});
foreach $pair (@pairs) {
($name, $value) = split(/=/, $pair);
$name =~ tr/A-Z/a-z/;
$name = 'QS_' . $name;
$value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C", hex($1))/eg;
eval "\$$name = \"$value\"";
}
$QS_s = 1 if ($QS_s eq '');
$QS_n = 3600 if ($QS_n eq '');
if ($QS_f eq '') {
print "HTTP/1.0 200 OK\n";
print "Content-type: text/html\n\n";
print "<b>ERROR</b>: No file given\n";
exit(0);
}
if (! -f $QS_f) {
print "HTTP/1.0 200 OK\n";
print "Content-type: text/html\n\n";
print "<b>ERROR</b>: File $QS_f not found\n";
exit(0);
}
sub print_http_headers_multipart_begin {
print "HTTP/1.0 200 OK\n";
$bound = "ThisRandomString12345";
print "Content-type: multipart/x-mixed-replace;boundary=$bound\n";
&print_http_headers_multipart_next;
}
sub print_http_headers_multipart_next {
print "\n--$bound\n";
}
sub print_http_headers_multipart_end {
print "\n--$bound--\n";
}
sub displayhtml {
local($buffer) = @_;
$len = length($buffer);
print "Content-type: text/html\n";
print "Content-length: $len\n\n";
print $buffer;
}
sub readfile {
local($file) = @_;
local(*FP, $size, $buffer, $bytes);
($x, $x, $x, $x, $x, $x, $x, $size) = stat($file);
$size = sprintf("%d", $size);
open(FP, "<$file");
$bytes = sysread(FP, $buffer, $size);
close(FP);
return $buffer;
}
$buffer = &readfile($QS_f);
&print_http_headers_multipart_begin;
&displayhtml($buffer);
sub mystat {
local($file) = $_[0];
local($time);
($x, $x, $x, $x, $x, $x, $x, $x, $x, $mtime) = stat($file);
return $mtime;
}
$mtimeL = &mystat($QS_f);
$mtime = $mtime;
for ($n = 0; $n < $QS_n; $n++) {
while (1) {
$mtime = &mystat($QS_f);
if ($mtime ne $mtimeL) {
$mtimeL = $mtime;
sleep(2);
$buffer = &readfile($QS_f);
&print_http_headers_multipart_next;
&displayhtml($buffer);
sleep(5);
$mtimeL = &mystat($QS_f);
last;
}
sleep($QS_s);
}
}
&print_http_headers_multipart_end;
exit(0);
##EOF##
The <VirtualHost> feature of Apache is nice
and works great when you just have a few dozen
virtual hosts. But when you are an ISP and have hundreds of
virtual hosts, this feature is suboptimal.
To provide this feature we map the remote web page or even
the complete remote web area to our namespace using the
Proxy Throughput feature (flag [P]):
##
## vhost.map
##
www.vhost1.dom:80 /path/to/docroot/vhost1
www.vhost2.dom:80 /path/to/docroot/vhost2
:
www.vhostN.dom:80 /path/to/docroot/vhostN
##
## httpd.conf
##
:
# use the canonical hostname on redirects, etc.
UseCanonicalName on
:
# add the virtual host in front of the CLF-format
CustomLog /path/to/access_log "%{VHOST}e %h %l %u %t \"%r\" %>s %b"
:
# enable the rewriting engine in the main server
RewriteEngine on
# define two maps: one for fixing the URL and one which defines
# the available virtual hosts with their corresponding
# DocumentRoot.
RewriteMap lowercase int:tolower
RewriteMap vhost txt:/path/to/vhost.map
# Now do the actual virtual host mapping
# via a huge and complicated single rule:
#
# 1. make sure we don't map for common locations
RewriteCond %{REQUEST_URI} !^/commonurl1/.*
RewriteCond %{REQUEST_URI} !^/commonurl2/.*
:
RewriteCond %{REQUEST_URI} !^/commonurlN/.*
#
# 2. make sure we have a Host header, because
# currently our approach only supports
# virtual hosting through this header
RewriteCond %{HTTP_HOST} !^$
#
# 3. lowercase the hostname
RewriteCond ${lowercase:%{HTTP_HOST}|NONE} ^(.+)$
#
# 4. lookup this hostname in vhost.map and
# remember it only when it is a path
# (and not "NONE" from above)
RewriteCond ${vhost:%1} ^(/.*)$
#
# 5. finally we can map the URL to its docroot location
# and remember the virtual host for logging purposes
RewriteRule ^/(.*)$ %1/$1 [E=VHOST:${lowercase:%{HTTP_HOST}}]
:
How can we forbid a list of externally configured hosts from using our server?
For Apache >= 1.3b6:
RewriteEngine on
RewriteMap hosts-deny txt:/path/to/hosts.deny
RewriteCond ${hosts-deny:%{REMOTE_HOST}|NOT-FOUND} !=NOT-FOUND [OR]
RewriteCond ${hosts-deny:%{REMOTE_ADDR}|NOT-FOUND} !=NOT-FOUND
RewriteRule ^/.* - [F]
For Apache <= 1.3b6:
RewriteEngine on
RewriteMap hosts-deny txt:/path/to/hosts.deny
RewriteRule ^/(.*)$ ${hosts-deny:%{REMOTE_HOST}|NOT-FOUND}/$1
RewriteRule !^NOT-FOUND/.* - [F]
RewriteRule ^NOT-FOUND/(.*)$ ${hosts-deny:%{REMOTE_ADDR}|NOT-FOUND}/$1
RewriteRule !^NOT-FOUND/.* - [F]
RewriteRule ^NOT-FOUND/(.*)$ /$1
## ## hosts.deny ## ## ATTENTION! This is a map, not a list, even when we treat it as such. ## mod_rewrite parses it for key/value pairs, so at least a ## dummy value "-" must be present for each entry. ## 193.102.180.41 - bsdti1.sdm.de - 192.76.162.40 -
How can we forbid a certain host or even a user of a special host from using the Apache proxy?
We first have to make sure mod_rewrite
is below(!) mod_proxy in the Configuration
file when compiling the Apache web server. This way it gets
called before mod_proxy. Then we
configure the following for a host-dependent deny...
RewriteCond %{REMOTE_HOST} ^badhost\.mydomain\.com$
RewriteRule !^http://[^/.]\.mydomain.com.* - [F]
...and this one for a user@host-dependent deny:
RewriteCond %{REMOTE_IDENT}@%{REMOTE_HOST} ^badguy@badhost\.mydomain\.com$
RewriteRule !^http://[^/.]\.mydomain.com.* - [F]
Sometimes very special authentication is needed, for
instance authentication which checks for a set of
explicitly configured users. Only these should receive
access and without explicit prompting (which would occur
when using Basic Auth via mod_auth).
We use a list of rewrite conditions to exclude all except our friends:
RewriteCond %{REMOTE_IDENT}@%{REMOTE_HOST} !^friend1@client1.quux-corp\.com$
RewriteCond %{REMOTE_IDENT}@%{REMOTE_HOST} !^friend2@client2.quux-corp\.com$
RewriteCond %{REMOTE_IDENT}@%{REMOTE_HOST} !^friend3@client3.quux-corp\.com$
RewriteRule ^/~quux/only-for-friends/ - [F]
How can we program a flexible URL Deflector which acts on the "Referer" HTTP header and can be configured with as many referring pages as we like?
Use the following really tricky ruleset...
RewriteMap deflector txt:/path/to/deflector.map
RewriteCond %{HTTP_REFERER} !=""
RewriteCond ${deflector:%{HTTP_REFERER}} ^-$
RewriteRule ^.* %{HTTP_REFERER} [R,L]
RewriteCond %{HTTP_REFERER} !=""
RewriteCond ${deflector:%{HTTP_REFERER}|NOT-FOUND} !=NOT-FOUND
RewriteRule ^.* ${deflector:%{HTTP_REFERER}} [R,L]
... in conjunction with a corresponding rewrite map:
## ## deflector.map ## http://www.badguys.com/bad/index.html - http://www.badguys.com/bad/index2.html - http://www.badguys.com/bad/index3.html http://somewhere.com/
This automatically redirects the request back to the
referring page (when "-" is used as the value
in the map) or to a specific URL (when an URL is specified
in the map as the second argument).
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