name mode size
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config 040000
doc 040000
Makefile 100644 300B
README 100644 20.23kB
allow_files.c 100644 19.32kB
allow_files.h 100644 2.26kB
im_db.c 100644 4.85kB
im_db.h 100644 1.32kB
im_hash.c 100644 7.16kB
im_hash.h 100644 2.71kB
im_locks.c 100644 2.68kB
im_locks.h 100644 1.69kB
im_rpc.c 100644 1.65kB
im_rpc.h 100644 1.24kB
ip_set.c 100644 5.59kB
ip_set.h 100644 1.81kB
ip_set_rpc.c 100644 7.34kB
ip_set_rpc.h 100644 2.13kB
ip_tree.c 100644 7.05kB
ip_tree.h 100644 4.11kB
ipmatch.c 100644 7.32kB
ipmatch.h 100644 1.51kB
parse_config.c 100644 7.13kB
parse_config.h 100644 1.26kB
permissions.c 100644 22.47kB
permissions.h 100644 2.38kB
permissions_rpc.h 100644 1.78kB
rule.c 100644 4.19kB
rule.h 100644 2.27kB
trusted.c 100644 8.81kB
trusted.h 100644 1.87kB
trusted_hash.c 100644 5.56kB
trusted_hash.h 100644 2.56kB
trusted_rpc.c 100644 2.18kB
trusted_rpc.h 100644 1.45kB
README
permissions Module Miklos Tirpak Edited by Miklos Tirpak Copyright � 2003 Miklos Tirpak Copyright (C) 2006 iptelorg GmbH _________________________________________________________ Table of Contents 1. User's Guide 1.1. Overview 1.1.1. Call Routing 1.1.2. Registration Permissions 1.1.3. Refer-To Permissions 1.1.4. Messages catching 1.2. Dependencies 1.2.1. SER Modules 1.2.2. External Libraries or Applications 1.3. Exported Parameters 1.3.1. default_allow_file (string) 1.3.2. default_deny_file (string) 1.3.3. check_all_branches (integer) 1.3.4. allow_suffix (string) 1.3.5. deny_suffix (string) 1.3.6. max_rule_files (int) 1.3.7. safe_file_load (int) 1.3.8. db_url (string) 1.3.9. db_mode (int) 1.4. Exported Functions 1.4.1. allow_routing() 1.4.2. allow_routing(basename) 1.4.3. allow_routing(allow_file, deny_file) 1.4.4. allow_register(basename) 1.4.5. allow_register(allow_file, deny_file) 1.4.6. allow_refer_to(basename) 1.4.7. allow_refer_to(allow_file, deny_file) 1.4.8. ipmatch (string/AVP/select, [avp]) 1.4.9. ipmatch_onsend (string) 1.5. XML-RPC interface 1.5.1. ipmatch.reload 2. Developer's Guide 3. Frequently Asked Questions List of Examples 1-1. Set default_allow_file parameter 1-2. Set default_deny_file parameter 1-3. Set check_all_branches parameter 1-4. Set allow_suffix parameter 1-5. Set deny_suffix parameter 1-6. allow_routing usage 1-7. allow_routing(basename) usage 1-8. allow_routing(allow_file, deny_file) usage 1-9. allow_register(basename) usage 1-10. allow_register(allow_file, deny_file) usage _________________________________________________________ Chapter 1. User's Guide 1.1. Overview 1.1.1. Call Routing The module can be used to determine if a call has appropriate permission to be established. Permission rules are stored in plaintext configuration files similar to hosts.allow and hosts.deny files used by tcpd. When allow_routing function is called it tries to find a rule that matches selected fields of the message. SER is a forking proxy and therefore a single message can be sent to different destinations simultaneously. When checking permissions all the destinations must be checked and if one of them fails, the forwarding will fail. The matching algorithm is as follows, first match wins: * Create a set of pairs of form (From, R-URI of branch 1), (From, R-URI of branch 2), etc. * Routing will be allowed when all pairs match an entry in the allow file. * Otherwise routing will be denied when one of pairs matches an entry in the deny file. * Otherwise, routing will be allowed. A non-existing permission control file is treated as if it were an empty file. Thus, permission control can be turned off by providing no permission control files. From header field and Request-URIs are always compared with regular expressions! For the syntax see the sample file: config/permissions.allow. _________________________________________________________ 1.1.2. Registration Permissions In addition to call routing it is also possible to check REGISTER messages and decide--based on the configuration files--whether the message should be allowed and the registration accepted or not. Main purpose of the function is to prevent registration of "prohibited" IP addresses. One example, when a malicious user registers a contact containing IP address of a PSTN gateway, he might be able to bypass authorization checks performed by the SIP proxy. That is undesirable and therefore attempts to register IP address of a PSTN gateway should be rejected. Files config/register.allow and config/register.deny contain an example configuration. Function for registration checking is called allow_register and the algorithm is very similar to the algorithm described in Section 1.1.1. The only difference is in the way how pairs are created. Instead of From header field the function uses To header field because To header field in REGISTER messages contains the URI of the person being registered. Instead of the Request-URI of branches the function uses Contact header field. Thus, pairs used in matching will look like this: (To, Contact 1), (To, Contact 2), (To, Contact 3), and so on.. The algorithm of matching is same as described in Section 1.1.1. _________________________________________________________ 1.1.3. Refer-To Permissions In addition to call routing and REGISTER it is also possible to check REFER messages and decide--based on the configuration files-- whether or not the message should be accepted for forwarding. Main purpose of the function is to prevent referring a SIP UA to "prohibited" IP addresses. One example is user sending a REFER request to PSTN gateway trying to refer it to an expensive phone number. Function for Refer-To checking is called allow_refer_to and the algorithm is very similar to the algorithm described in Section 1.1.1. The only difference is in the way how pairs are created. Instead of Request-URI the function uses Refer-To header field because Refer-To header field in REFER messages contains the URI to which the UA is being referred to. The algorithm of matching is same as described in Section 1.1.1. _________________________________________________________ 1.1.4. Messages catching The module can be also used for catching messages coming from or going to specific network elements, for example gateways or peering partners. Users can register or forward the calls to the address of a gateway resulting unauthorized access to them. Such calls must be catched and dropped, see ipmatch functions for details. _________________________________________________________ 1.2. Dependencies 1.2.1. SER Modules The following modules must be loaded before this module: * database module * xmlrpc module _________________________________________________________ 1.2.2. External Libraries or Applications The following libraries or applications must be installed before running SER with this module loaded: * None. _________________________________________________________ 1.3. Exported Parameters 1.3.1. default_allow_file (string) Default allow file used by functions without parameters. If you don't specify full pathname then the directory in which is the main config file is located will be used. Default value is "permissions.allow". Example 1-1. Set default_allow_file parameter ... modparam("permissions", "default_allow_file", "/etc/permissions.allow") ... _________________________________________________________ 1.3.2. default_deny_file (string) Default file containing deny rules. The file is used by functions without parameters. If you don't specify full pathname then the directory in which the main config file is located will be used. Default value is "permissions.deny". Example 1-2. Set default_deny_file parameter ... modparam("permissions", "default_deny_file", "/etc/permissions.deny") ... If both of the default file parameters are set to "" the module does not try to load them. _________________________________________________________ 1.3.3. check_all_branches (integer) If set then allow_routing functions will check Request-URI of all branches (default). If disabled then only Request-URI of the first branch will be checked. Warning Do not disable this parameter unless you really know what you are doing. Default value is 1. Example 1-3. Set check_all_branches parameter ... modparam("permissions", "check_all_branches", 0) ... _________________________________________________________ 1.3.4. allow_suffix (string) Suffix to be appended to basename to create filename of the allow file when version with one parameter of either allow_routing or allow_register is used. Note Including leading dot. Default value is ".allow". Example 1-4. Set allow_suffix parameter ... modparam("permissions", "allow_suffix", ".allow") ... _________________________________________________________ 1.3.5. deny_suffix (string) Suffix to be appended to basename to create filename of the deny file when version with one parameter of either allow_routing or allow_register is used. Note Including leading dot. Default value is ".deny". Example 1-5. Set deny_suffix parameter ... modparam("permissions", "deny_suffix", ".deny") ... _________________________________________________________ 1.3.6. max_rule_files (int) Maximum number of allow/deny file pairs. Default value is 64. _________________________________________________________ 1.3.7. safe_file_load (int) Module initialization fails in case of a missing config file if safe_file_load is true. Default value is 0 (false). _________________________________________________________ 1.3.8. db_url (string) URL of the database to be used. _________________________________________________________ 1.3.9. db_mode (int) Disables/enables database cache. Default value is 0 (cache is disabled) NOTE: ipmatch functions can operate only in cache mode, set db_mode to 1 if you want to use them. _________________________________________________________ 1.3.10. ipmatch_table (string) Name of the table containing ipmatch entries. Default value is "ipmatch". _________________________________________________________ 1.4. Exported Functions 1.4.1. allow_routing() Returns true if all pairs constructed as described in Section 1.1.1 have appropriate permissions according to the configuration files. This function uses default configuration files specified in default_allow_file and default_deny_file. Example 1-6. allow_routing usage ... if (allow_routing()) { t_relay(); }; ... _________________________________________________________ 1.4.2. allow_routing(basename) Returns true if all pairs constructed as described in Section 1.1.1 have appropriate permissions according to the configuration files given as parameters. Meaning of the parameters is as follows: * basename - Basename from which allow and deny filenames will be created by appending contents of allow_suffix and deny_suffix parameters. If the parameter doesn't contain full pathname then the function expects the file to be located in the same directory as the main configuration file of the server. Example 1-7. allow_routing(basename) usage ... if (allow_routing("basename")) { t_relay(); }; ... _________________________________________________________ 1.4.3. allow_routing(allow_file, deny_file) Returns true if all pairs constructed as described in Section 1.1.1 have appropriate permissions according to the configuration files given as parameters. Meaning of the parameters is as follows: * allow_file - File containing allow rules. If the parameter doesn't contain full pathname then the function expects the file to be located in the same directory as the main configuration file of the server. * deny_file - File containing deny rules. If the parameter doesn't contain full pathname then the function expects the file to be located in the same directory as the main configuration file of the server. Example 1-8. allow_routing(allow_file, deny_file) usage ... if (allow_routing("rules.allow", "rules.deny")) { t_relay(); }; ... _________________________________________________________ 1.4.4. allow_register(basename) The function returns true if all pairs constructed as described in Section 1.1.2 have appropriate permissions according to the configuration files given as parameters. Meaning of the parameters is as follows: * basename - Basename from which allow and deny filenames will be created by appending contents of allow_suffix and deny_suffix parameters. If the parameter doesn't contain full pathname then the function expects the file to be located in the same directory as the main configuration file of the server. Example 1-9. allow_register(basename) usage ... if (method=="REGISTER") { if (allow_register("register")) { save("location"); break; } else { sl_send_reply("403", "Forbidden"); }; }; ... _________________________________________________________ 1.4.5. allow_register(allow_file, deny_file) The function returns true if all pairs constructed as described in Section 1.1.2 have appropriate permissions according to the configuration files given as parameters. Meaning of the parameters is as follows: * allow_file - File containing allow rules. If the parameter doesn't contain full pathname then the function expects the file to be located in the same directory as the main configuration file of the server. * deny_file - File containing deny rules. If the parameter doesn't contain full pathname then the function expects the file to be located in the same directory as the main configuration file of the server. Example 1-10. allow_register(allow_file, deny_file) usage ... if (method=="REGISTER") { if (allow_register("register.allow", "register.deny")) { save("location"); break; } else { sl_send_reply("403", "Forbidden"); }; }; ... _________________________________________________________ 1.4.6. allow_refer_to(basename) The function returns true if all pairs constructed as described in Section 1.1.2 have appropriate permissions according to the configuration files given as parameters. Meaning of the parameters is as follows: * basename - Basename from which allow and deny filenames will be created by appending contents of allow_suffix and deny_suffix parameters. If the parameter doesn't contain full pathname then the function expects the file to be located in the same directory as the main configuration file of the server. Example 1-11. allow_refer_to(basename) usage ... if (method=="REFER") { if (allow_refer_to("refer")) { ... } else { sl_send_reply("403", "Forbidden"); }; }; ... _________________________________________________________ 1.4.7. allow_refer_to(allow_file, deny_file) The function returns true if all pairs constructed as described in Section 1.1.2 have appropriate permissions according to the configuration files given as parameters. Meaning of the parameters is as follows: * allow_file - File containing allow rules. If the parameter doesn't contain full pathname then the function expects the file to be located in the same directory as the main configuration file of the server. * deny_file - File containing deny rules. If the parameter doesn't contain full pathname then the function expects the file to be located in the same directory as the main configuration file of the server. Example 1-11. allow_register(allow_file, deny_file) usage ... if (method=="REFER") { if (allow_register("refer.allow", "refer.deny")) { ... } else { sl_send_reply("403", "Forbidden"); }; }; ... _________________________________________________________ 1.4.8. ipmatch (string/AVP/select, [avp]) The function tries to find an IP address and port pair (defined by the first function parameter) in the cached database table. Port is optional, it is compared only if both the function parameter and the database entry contain it. The first parameter can be: - string: "src": the source address of the packet is used "via2": the ip address of the 2nd via line is used other values are not defined currently - AVP: e.g. "$myavp" - Select call: e.g. "@via[0].host" The second parameter is optional, it is used to set an AVP value from the database. Suitable for assigning logical identifiers to gateways. Note that IPv6 addresses must be enclosed in square brackets in case of port is defined: [1111:2222::3333]:5060 _________________________________________________________ 1.4.9. ipmatch_onsend (string) ipmatch() function replacement for onsend_route block. The function accepts only string parameter, because even AVP reading is unsafe in onsend_route. the parameter can be: - "dst": the destination address is used - "ruri": the ip:port pair is extracted from the Request URI The function can be used for example to catch unauthorized requests going to gateways: Use a flag to mark the call as PSTN either in request or in failure_route, and do not touch it in onreply_route. See the examples below. _________________________________________________________ 1.4.10. ipmatch_filter (unsigned int) Entries in the database can be marked to group the different kind of network elements. The function sets the filter which is used on the mark while comparing the IP addresses. The mark must be the power of 2 in the database! Note that ipmatch() and ipmatch_onsend() functions reset the filter! Example: +-----------------+-------------------+------+------+ | ip | avp_val | mark | flag | +-----------------+-------------------+------+------+ | 1111:2222::1001 | first_gw | 1 | 1 | | 10.38.2.10:5060 | second_gw | 1 | 1 | | 10.0.0.10 | first_peering | 2 | 1 | +-----------------+-------------------+------+------+ route[0] { # is this a request from a GW? ipmatch_filter("1"); if (ipmatch("src", "$gw_id")) { # yes, it is from a GW ... } else { # is this a request from a peering partner? ipmatch_filter("2"); if (ipmatch("src", "$peering_id")) { # yes, it is from a peering partner ... }; } ... # request goes to PSTN setflag(PSTN); } onsend_route[0] { if (method == "INVITE" && (!isflagset(PSTN))) { # is this a request to a GW? ipmatch_filter("1"); if (ipmatch_onsend("dst")) { # request is not marked with PSTN flag, but it goes to a gateway drop; } } ... } _________________________________________________________ 1.5. XML-RPC interface 1.5.1. ipmatch.reload Reloads the cached ipmatch table. The original table remains active in case of any failure. _________________________________________________________ Chapter 2. Developer's Guide The module does not provide any sort of API to use in other SER modules. _________________________________________________________ Chapter 3. Frequently Asked Questions 3.1. Where can I find more about SER? 3.2. Where can I post a question about this module? 3.3. How can I report a bug? 3.1. Where can I find more about SER? Take a look at http://iptel.org/ser. 3.2. Where can I post a question about this module? First at all check if your question was already answered on one of our mailing lists: * http://mail.iptel.org/mailman/listinfo/serusers * http://mail.iptel.org/mailman/listinfo/serdev E-mails regarding any stable version should be sent to <serusers@iptel.org> and e-mail regarding development versions or CVS snapshots should be send to <serdev@iptel.org>. 3.3. How can I report a bug? Please follow the guidelines provided at: http://iptel.org/ser/bugs