1DBI::ProxyServer(3) User Contributed Perl Documentation DBI::ProxyServer(3)
2
6 DBI::ProxyServer - a server for the DBD::Proxy driver
7
9 use DBI::ProxyServer;
10 DBI::ProxyServer::main(@ARGV);
11
13 DBI::Proxy Server is a module for implementing a proxy for the DBI
14 proxy driver, DBD::Proxy. It allows access to databases over the net‐
15 work if the DBMS does not offer networked operations. But the proxy
16 server might be usefull for you, even if you have a DBMS with inte‐
17 grated network functionality: It can be used as a DBI proxy in a fire‐
18 walled environment.
19 DBI::ProxyServer runs as a daemon on the machine with the DBMS or on
21 the firewall. The client connects to the agent using the DBI driver
22 DBD::Proxy, thus in the exactly same way than using DBD::mysql,
23 DBD::mSQL or any other DBI driver.
24 The agent is implemented as a RPC::PlServer application. Thus you have
26 access to all the possibilities of this module, in particular encryp‐
27 tion and a similar configuration file. DBI::ProxyServer adds the possi‐
28 bility of query restrictions: You can define a set of queries that a
29 client may execute and restrict access to those. (Requires a DBI driver
30 that supports parameter binding.) See "CONFIGURATION FILE".
31 The provided driver script, dbiproxy, may either be used as it is or
33 used as the basis for a local version modified to meet your needs.
34
36 When calling the DBI::ProxyServer::main() function, you supply an array
37 of options. These options are parsed by the Getopt::Long module. The
38 ProxyServer inherits all of RPC::PlServer's and hence Net::Daemon's
39 options and option handling, in particular the ability to read options
40 from either the command line or a config file. See RPC::PlServer. See
41 Net::Daemon. Available options include
42 chroot (--chroot=dir)
44 (UNIX only) After doing a bind(), change root directory to the
45 given directory by doing a chroot(). This is usefull for security,
46 but it restricts the environment a lot. For example, you need to
47 load DBI drivers in the config file or you have to create hard
48 links to Unix sockets, if your drivers are using them. For example,
49 with MySQL, a config file might contain the following lines:
50 my $rootdir = '/var/dbiproxy';
52 my $unixsockdir = '/tmp';
53 my $unixsockfile = 'mysql.sock';
54 foreach $dir ($rootdir, "$rootdir$unixsockdir") {
55 mkdir 0755, $dir;
56 }
57 link("$unixsockdir/$unixsockfile",
58 "$rootdir$unixsockdir/$unixsockfile");
59 require DBD::mysql;
60 {
62 'chroot' => $rootdir,
63 ...
64 }
65 If you don't know chroot(), think of an FTP server where you can
67 see a certain directory tree only after logging in. See also the
68 --group and --user options.
69 clients
71 An array ref with a list of clients. Clients are hash refs, the
72 attributes accept (0 for denying access and 1 for permitting) and
73 mask, a Perl regular expression for the clients IP number or its
74 host name.
75 configfile (--configfile=file)
77 Config files are assumed to return a single hash ref that overrides
78 the arguments of the new method. However, command line arguments in
79 turn take precedence over the config file. See the "CONFIGURATION
80 FILE" section below for details on the config file.
81 debug (--debug)
83 Turn debugging mode on. Mainly this asserts that logging messages
84 of level "debug" are created.
85 facility (--facility=mode)
87 (UNIX only) Facility to use for Sys::Syslog. The default is daemon.
88 group (--group=gid)
90 After doing a bind(), change the real and effective GID to the
91 given. This is usefull, if you want your server to bind to a priv‐
92 ileged port (<1024), but don't want the server to execute as root.
93 See also the --user option.
94 GID's can be passed as group names or numeric values.
96 localaddr (--localaddr=ip)
98 By default a daemon is listening to any IP number that a machine
99 has. This attribute allows to restrict the server to the given IP
100 number.
101 localport (--localport=port)
103 This attribute sets the port on which the daemon is listening. It
104 must be given somehow, as there's no default.
105 logfile (--logfile=file)
107 Be default logging messages will be written to the syslog (Unix) or
108 to the event log (Windows NT). On other operating systems you need
109 to specify a log file. The special value "STDERR" forces logging to
110 stderr. See Net::Daemon::Log for details.
111 mode (--mode=modename)
113 The server can run in three different modes, depending on the envi‐
114 ronment.
115 If you are running Perl 5.005 and did compile it for threads, then
117 the server will create a new thread for each connection. The thread
118 will execute the server's Run() method and then terminate. This
119 mode is the default, you can force it with "--mode=threads".
120 If threads are not available, but you have a working fork(), then
122 the server will behave similar by creating a new process for each
123 connection. This mode will be used automatically in the absence of
124 threads or if you use the "--mode=fork" option.
125 Finally there's a single-connection mode: If the server has
127 accepted a connection, he will enter the Run() method. No other
128 connections are accepted until the Run() method returns (if the
129 client disconnects). This operation mode is usefull if you have
130 neither threads nor fork(), for example on the Macintosh. For
131 debugging purposes you can force this mode with "--mode=single".
132 pidfile (--pidfile=file)
134 (UNIX only) If this option is present, a PID file will be created
135 at the given location. Default is to not create a pidfile.
136 user (--user=uid)
138 After doing a bind(), change the real and effective UID to the
139 given. This is usefull, if you want your server to bind to a priv‐
140 ileged port (<1024), but don't want the server to execute as root.
141 See also the --group and the --chroot options.
142 UID's can be passed as group names or numeric values.
144 version (--version)
146 Supresses startup of the server; instead the version string will be
147 printed and the program exits immediately.
148
150 The configuration file is just that of RPC::PlServer or Net::Daemon
151 with some additional attributes in the client list.
152 The config file is a Perl script. At the top of the file you may
154 include arbitraty Perl source, for example load drivers at the start
155 (usefull to enhance performance), prepare a chroot environment and so
156 on.
157 The important thing is that you finally return a hash ref of option
159 name/value pairs. The possible options are listed above.
160 All possibilities of Net::Daemon and RPC::PlServer apply, in particular
162 Host and/or User dependent access control
164 Host and/or User dependent encryption
165 Changing UID and/or GID after binding to the port
166 Running in a chroot() environment
167 Additionally the server offers you query restrictions. Suggest the fol‐
169 lowing client list:
170 'clients' => [
172 { 'mask' => '^admin\.company\.com$',
173 'accept' => 1,
174 'users' => [ 'root', 'wwwrun' ],
175 },
176 {
177 'mask' => '^admin\.company\.com$',
178 'accept' => 1,
179 'users' => [ 'root', 'wwwrun' ],
180 'sql' => {
181 'select' => 'SELECT * FROM foo',
182 'insert' => 'INSERT INTO foo VALUES (?, ?, ?)'
183 }
184 }
185 then only the users root and wwwrun may connect from admin.company.com,
187 executing arbitrary queries, but only wwwrun may connect from other
188 hosts and is restricted to
189 $sth->prepare("select");
191 or
193 $sth->prepare("insert");
195 which in fact are "SELECT * FROM foo" or "INSERT INTO foo VALUES (?, ?,
197 ?)".
198
200 This section tells you how to restrict a DBI-Proxy: Not every user from
201 every workstation shall be able to execute every query.
202 There is a perl program "dbiproxy" which runs on a machine which is
204 able to connect to all the databases we wish to reach. All Perl-DBD-
205 drivers must be installed on this machine. You can also reach databases
206 for which drivers are not available on the machine where you run the
207 programm querying the database, e.g. ask MS-Access-database from Linux.
208 Create a configuration file "proxy_oracle.cfg" at the dbproxy-server:
210 {
212 # This shall run in a shell or a DOS-window
213 # facility => 'daemon',
214 pidfile => 'your_dbiproxy.pid',
215 logfile => 1,
216 debug => 0,
217 mode => 'single',
218 localport => '12400',
219 # Access control, the first match in this list wins!
221 # So the order is important
222 clients => [
223 # hint to organize:
224 # the most specialized rules for single machines/users are 1st
225 # then the denying rules
226 # the the rules about whole networks
227 # rule: internal_webserver
229 # desc: to get statistical information
230 {
231 # this IP-address only is meant
232 mask => '^10\.95\.81\.243$',
233 # accept (not defer) connections like this
234 accept => 1,
235 # only users from this list
236 # are allowed to log on
237 users => [ 'informationdesk' ],
238 # only this statistical query is allowed
239 # to get results for a web-query
240 sql => {
241 alive => 'select count(*) from dual',
242 statistic_area => 'select count(*) from e01admin.e01e203 where geb_bezei like ?',
243 }
244 },
245 # rule: internal_bad_guy_1
247 {
248 mask => '^10\.95\.81\.1$',
249 accept => 0,
250 },
251 # rule: employee_workplace
253 # desc: get detailled informations
254 {
255 # any IP-address is meant here
256 mask => '^10\.95\.81\.(\d+)$',
257 # accept (not defer) connections like this
258 accept => 1,
259 # only users from this list
260 # are allowed to log on
261 users => [ 'informationdesk', 'lippmann' ],
262 # all these queries are allowed:
263 sql => {
264 search_city => 'select ort_nr, plz, ort from e01admin.e01e200 where plz like ?',
265 search_area => 'select gebiettyp, geb_bezei from e01admin.e01e203 where geb_bezei like ? or geb_bezei like ?',
266 }
267 },
268 # rule: internal_bad_guy_2
270 # This does NOT work, because rule "employee_workplace" hits
271 # with its ip-address-mask of the whole network
272 {
273 # don't accept connection from this ip-address
274 mask => '^10\.95\.81\.5$',
275 accept => 0,
276 }
277 ]
278 }
279 Start the proxyserver like this:
281 rem well-set Oracle_home needed for Oracle
283 set ORACLE_HOME=d:\oracle\ora81
284 dbiproxy --configfile proxy_oracle.cfg
285 Testing the connection from a remote machine
287 Call a programm "dbish" from your commandline. I take the machine from
289 rule "internal_webserver"
290 dbish "dbi:Proxy:hostname=oracle.zdf;port=12400;dsn=dbi:Oracle:e01" informationdesk xxx
292 There will be a shell-prompt:
294 informationdesk@dbi...> alive
296 Current statement buffer (enter '/'...):
298 alive
299 informationdesk@dbi...> /
301 COUNT(*)
302 '1'
303 [1 rows of 1 fields returned]
304 Testing the connection with a perl-script
306 Create a perl-script like this:
308 # file: oratest.pl
310 # call me like this: perl oratest.pl user password
311 use strict;
313 use DBI;
314 my $user = shift ⎪⎪ die "Usage: $0 user password";
316 my $pass = shift ⎪⎪ die "Usage: $0 user password";
317 my $config = {
318 dsn_at_proxy => "dbi:Oracle:e01",
319 proxy => "hostname=oechsle.zdf;port=12400",
320 };
321 my $dsn = sprintf "dbi:Proxy:%s;dsn=%s",
322 $config->{proxy},
323 $config->{dsn_at_proxy};
324 my $dbh = DBI->connect( $dsn, $user, $pass )
326 ⎪⎪ die "connect did not work: $DBI::errstr";
327 my $sql = "search_city";
329 printf "%s\n%s\n%s\n", "="x40, $sql, "="x40;
330 my $cur = $dbh->prepare($sql);
331 $cur->bind_param(1,'905%');
332 &show_result ($cur);
333 my $sql = "search_area";
335 printf "%s\n%s\n%s\n", "="x40, $sql, "="x40;
336 my $cur = $dbh->prepare($sql);
337 $cur->bind_param(1,'Pfarr%');
338 $cur->bind_param(2,'Bronnamberg%');
339 &show_result ($cur);
340 my $sql = "statistic_area";
342 printf "%s\n%s\n%s\n", "="x40, $sql, "="x40;
343 my $cur = $dbh->prepare($sql);
344 $cur->bind_param(1,'Pfarr%');
345 &show_result ($cur);
346 $dbh->disconnect;
348 exit;
349 sub show_result {
351 my $cur = shift;
352 unless ($cur->execute()) {
353 print "Could not execute\n";
354 return;
355 }
356 my $rownum = 0;
358 while (my @row = $cur->fetchrow_array()) {
359 printf "Row is: %s\n", join(", ",@row);
360 if ($rownum++ > 5) {
361 print "... and so on\n";
362 last;
363 }
364 }
365 $cur->finish;
366 }
367 The result
369 C:\>perl oratest.pl informationdesk xxx
371 ========================================
372 search_city
373 ========================================
374 Row is: 3322, 9050, Chemnitz
375 Row is: 3678, 9051, Chemnitz
376 Row is: 10447, 9051, Chemnitz
377 Row is: 12128, 9051, Chemnitz
378 Row is: 10954, 90513, Zirndorf
379 Row is: 5808, 90513, Zirndorf
380 Row is: 5715, 90513, Zirndorf
381 ... and so on
382 ========================================
383 search_area
384 ========================================
385 Row is: 101, Bronnamberg
386 Row is: 400, Pfarramt Zirndorf
387 Row is: 400, Pfarramt Rosstal
388 Row is: 400, Pfarramt Oberasbach
389 Row is: 401, Pfarramt Zirndorf
390 Row is: 401, Pfarramt Rosstal
391 ========================================
392 statistic_area
393 ========================================
394 DBD::Proxy::st execute failed: Server returned error: Failed to execute method CallMethod: Unknown SQL query: statistic_area at E:/Perl/site/lib/DBI/ProxyServer.pm line 258.
395 Could not execute
396 How the configuration works
398 The most important section to control access to your dbi-proxy is
400 "client=>" in the file "proxy_oracle.cfg":
401 Controlling which person at which machine is allowed to access
403 * "mask" is a perl regular expression against the plain ip-address of
405 the machine which wishes to connect _or_ the reverse-lookup from a
406 nameserver.
407 * "accept" tells the dbiproxy-server wether ip-adresse like in "mask"
408 are allowed to connect or not (0/1)
409 * "users" is a reference to a list of usernames which must be matched,
410 this is NOT a regular expression.
411 Controlling which SQL-statements are allowed
413 You can put every SQL-statement you like in simply ommiting "sql =>
415 ...", but the more important thing is to restrict the connection so
416 that only allowed queries are possible.
417 If you include an sql-section in your config-file like this:
419 sql => {
421 alive => 'select count(*) from dual',
422 statistic_area => 'select count(*) from e01admin.e01e203 where geb_bezei like ?',
423 }
424 The user is allowed to put two queries against the dbi-proxy. The
426 queries are _not_ "select count(*)...", the queries are "alive" and
427 "statistic_area"! These keywords are replaced by the real query. So you
428 can run a query for "alive":
429 my $sql = "alive";
431 my $cur = $dbh->prepare($sql);
432 ...
433 The flexibility is that you can put parameters in the where-part of the
435 query so the query are not static. Simply replace a value in the where-
436 part of the query through a question mark and bind it as a parameter to
437 the query.
438 my $sql = "statistic_area";
440 my $cur = $dbh->prepare($sql);
441 $cur->bind_param(1,'905%');
442 # A second parameter would be called like this:
443 # $cur->bind_param(2,'98%');
444 The result is this query:
446 select count(*) from e01admin.e01e203
448 where geb_bezei like '905%'
449 Don't try to put parameters into the sql-query like this:
451 # Does not work like you think.
453 # Only the first word of the query is parsed,
454 # so it's changed to "statistic_area", the rest is omitted.
455 # You _have_ to work with $cur->bind_param.
456 my $sql = "statistic_area 905%";
457 my $cur = $dbh->prepare($sql);
458 ...
459 Problems
461 * I don't know how to restrict users to special databases.
463 * I don't know how to pass query-parameters via dbish
464
466 Copyright (c) 1997 Jochen Wiedmann
467 Am Eisteich 9
468 72555 Metzingen
469 Germany
470 Email: joe@ispsoft.de
472 Phone: +49 7123 14881
473 The DBI::ProxyServer module is free software; you can redistribute it
475 and/or modify it under the same terms as Perl itself. In particular
476 permission is granted to Tim Bunce for distributing this as a part of
477 the DBI.
478
480 dbiproxy, DBD::Proxy, DBI, RPC::PlServer, RPC::PlClient, Net::Daemon,
481 Net::Daemon::Log, Sys::Syslog, Win32::EventLog, syslog
482perl v5.8.8 2006-02-07 DBI::ProxyServer(3)