Table of Contents
default_allow_file (string)
default_deny_file (string)
check_all_branches (integer)
allow_suffix (string)
deny_suffix (string)
db_url (string)
address_table (string)
grp_col (string)
ip_addr_col (string)
mask_col (string)
port_col (string)
db_mode (integer)
trusted_table (string)
source_col (string)
proto_col (string)
from_col (string)
ruri_col (string)
tag_col (string)
priority_col (string)
peer_tag_avp (AVP string)
peer_tag_mode (integer)
max_subnets (int)
load_backends (int)
allow_routing()
allow_routing(basename)
allow_routing(allow_file,deny_file)
allow_register(basename)
allow_register(allow_file, deny_file)
allow_uri(basename, pvar)
allow_address(group_id, ip_addr_pvar, port_pvar)
allow_source_address([group_id])
allow_source_address_group()
allow_address_group(addr, port)
allow_trusted([src_ip_pvar, proto_pvar, furi_pvar])
List of Examples
default_allow_file parameterdefault_deny_file parametercheck_all_branches parameterallow_suffix parameterdeny_suffix parameterdb_url parameteraddress_table parametergrp_col parameterip_addr_col parametermask_col parameterport_col parameterdb_mode parametertrusted_table parametersource_col parameterproto_col parameterfrom_col parameterruri_col parametertag_col parameterpriority_col parameterpeer_tag_avp parameterpeer_tag_mode parametermax_subnets parameterload_backends parameterallow_routing usageallow_routing(basename) usageallow_routing(allow_file, deny_file) usageallow_register(basename) usageallow_register(allow_file, deny_file) usageallow_uri(basename, pvar) usageallow_address() usageallow_source_address(group_id) usageallow_source_address_group() usageallow_source_address_group() usageallow_trusted() usageTable of Contents
default_allow_file (string)
default_deny_file (string)
check_all_branches (integer)
allow_suffix (string)
deny_suffix (string)
db_url (string)
address_table (string)
grp_col (string)
ip_addr_col (string)
mask_col (string)
port_col (string)
db_mode (integer)
trusted_table (string)
source_col (string)
proto_col (string)
from_col (string)
ruri_col (string)
tag_col (string)
priority_col (string)
peer_tag_avp (AVP string)
peer_tag_mode (integer)
max_subnets (int)
load_backends (int)
allow_routing()
allow_routing(basename)
allow_routing(allow_file,deny_file)
allow_register(basename)
allow_register(allow_file, deny_file)
allow_uri(basename, pvar)
allow_address(group_id, ip_addr_pvar, port_pvar)
allow_source_address([group_id])
allow_source_address_group()
allow_address_group(addr, port)
allow_trusted([src_ip_pvar, proto_pvar, furi_pvar])
The Permissions module provides functions for handling IP based access control lists (ACL) in a number of ways.
Call Routing
Registration permissions
URI permissions
Address permissions
Trusted Requests
The Address permissions and Trusted request handling supports using a database to load ACLs into RAM for fast processing.
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.
Kamailio 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.
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.
The function for registration checking is called allow_register and the algorithm is very
similar to the algorithm described in
Section 1.1, “Call Routing”. The only difference is in the way
how pairs are created.
Instead of the From header field the function uses the To header field because th To header field in REGISTER messages contains the URI of the person being registered. Instead of the Request-URI of branches the function uses the Contact header field.
Thus, the 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 the same as described in Section 1.1, “Call Routing”.
The module can be used to determine if a request to a destination
is allowed, based on an URI stored in a pvar. Permission rules are
stored in plaintext configuration files similar to
hosts.allow and
hosts.deny used by tcpd.
When the allow_uri
function is called, it tries to find a rule that matches
selected fields of the message.
The matching algorithm is as follows, where the first match wins:
Create a pair <From URI, URI stored in pvar>.
Request will be allowed when the pair matches an entry in the allow file.
Request will be denied when the pair matches an entry in the deny file.
Otherwise, request 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.
The From URI and the URI stored in pvar are always compared with regular
expressions! For the syntax see the sample file:
config/permissions.allow.
The module can be used to determine if an address (IP address and port or DNS domain name) matches any of the addresses stored in a cached Kamailio database table. IP addresses in the database table can be subnet addresses. Port 0 in cached database table matches any port. The address and port to be matched can be either taken from the request (allow_source_address) or given as pvar arguments (allow_address).
Addresses stored in the database table can be grouped together into one or more groups specified by a group identifier (positive integer value, i.e., equal or greater than 1). The group identifier is given as an argument to the allow_address() and allow_source_address() functions. One group can contain all of the three types of addresses: exact IP address, subnet IP address or DNS domain name.
When the argument is an IP address, it is tried to be matched with the records from that group that are of type exact IP or subnet. If the argument is not an IP it is tried to be matched with the records that are DNS domain names. No DNS lookup is performed, only strict matching.
As a side effect of matching the address, non-NULL tag (see tag_col module parameter) is added as value to peer_tag AVP if peer_tag_avp module parameter has been defined.
The module can be used to determine if an incoming request can be trusted without authentication.
When the allow_trusted
function is called, it tries to find a rule that matches
the request. Rules contain the following fields:
<source address, transport protocol, regular
expression>.
A requests is accepted if there exists a rule, where
source address is equal to the source address of the request or the source address given in pvar,
transport protocol is either "ANY" or equal to the transport protocol of request or the transport protocol given in pvar, and
regular expression is either empty (NULL in database) or matches the request's From (or optionally provided) URI.
Otherwise the request is rejected.
As a side effect of accepting the request, the peer's non-NULL tag (see tag_col module parameter) is added as value to peer_tag AVP if the peer_tag_avp module parameter has been defined.
Rules are stored in a database table specified by the module
parameters. There is a module parameter called
db_mode that
determines if the rules are cached into memory for faster
matching or if the database is consulted for each invocation
of the allow_trusted() function call.
The following modules must be loaded before this module:
No dependencies on other Kamailio modules.
Default allow file used by the functions with no parameters. If you don't specify a 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")
...
Default file containing deny rules. The file is used by functions with no parameters. If you don't specify a 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 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.
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)
...
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.
Including leading dot.
Default value is “.allow”.
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.
Including leading dot.
Default value is “.deny”.
This is URL of the database to be used to store rules used by
allow_trusted function.
Default value is “NULL”.
Example 1.6. Set db_url parameter
...
modparam("permissions", "db_url", "dbdriver://username:password@dbhost/dbname")
...
The name of the database table containing IP subnets and DNS domain names used by
allow_address and
allow_source_address
functions.
Default value is “address”.
Name of address table column containing the group identifier of the address.
Default value is “grp”.
Name of address table column containing the IP address part of the address.
Default value is “ip_addr”.
Name of address table column containing the network mask of the address. Possible values are 0-32 for IPv4 and 0-128 for IPv6 addresses. If the value is 0, the network mask is set to 32 for IPv4 addresses and to 128 for IPv6 addresses.
Default value is “mask”.
Name of address table column containing the port part of the address.
Default value is “port”.
Database mode. 0 means non-caching, 1 means caching.
Valid only for the allow_trusted function.
Default value is 0 (non-caching).
Name of database table containing the matching rules used by
the allow_trusted function.
Default value is “trusted”.
Name of column in the “trusted” table containing the source IP address that is matched against source IP address of received request.
Default value is “src_ip”.
Example 1.14. Set source_col parameter
...
modparam("permissions", "source_col", "source_ip_address")
...
Name of column in the “trusted” table containing the transport protocol that is matched against transport protocol of the received request. Possible values that can be stored in proto_col are “any”, “udp”, “tcp”, “tls”, “sctp”, “ws”, “wss”, and “none”. Value “any” matches always and value “none” never.
Default value is “proto”.
Name of the column trusted table containing a regular expression that is matched against the From URI.
Default value is “from_pattern”.
Name of the column trusted table containing a regular expression that is matched against the Request URI.
Default value is “ruri_pattern”.
Name of the column in the “address” or “trusted” table containing a string that is added as value to peer_tag AVP if peer_tag AVP has been defined and if the address or peer matches.
Default value is “tag”.
The column name used to store the priority of the corresponding rule from the database row. Priority values should be integer. When db_mode is set to 1 (caching), priorities are ordered from highest to lowest. In non-caching mode, priority order (ASC vs DESC) is determined by database.
Default value is “priority”.
Example 1.19. Set priority_col parameter
...
modparam("permissions", "priority_col", "column_name")
...
If defined, the AVP will be
set as a side effect of allow_trusted
call to not NULL tag column value of the matching peer.
Default value is “undefined”.
Example 1.20. Set peer_tag_avp parameter
...
modparam("permissions", "peer_tag_avp", "$avp(i:707)")
...
Tag mode for allow_trusted.
“0” sets only the tag of the first match.
“1” adds the tags of all matches to the avp. In addition
the return value of allow_trusted
is the number of matches. This parameter is not used for address table matching functions.
Default value is “0”.
The maximum number of subnet addresses to be loaded from address table.
Default value is “512”.
Control what backends should be loaded: 1 - address table; 2 - trusted table; 4 - allow file; 8 - deny file.
It can be a combination (sum) of the options to load many backends (e.g., 3 - loads address and trusted tables).
Default value is “0xffff” (load all backends).
Returns true if all pairs constructed as described in Section 1.1, “Call Routing” have appropriate permissions according to
the configuration files. This function uses default configuration
files specified in default_allow_file and
default_deny_file.
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
Returns true if all pairs constructed as described in Section 1.1, “Call Routing” 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.
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
Returns true if all pairs constructed as described in Section 1.1, “Call Routing” 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.
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
Example 1.26. allow_routing(allow_file, deny_file) usage
...
if (allow_routing("rules.allow", "rules.deny")) {
t_relay();
};
...
The function returns true if all pairs constructed as described in Section 1.2, “Registration Permissions” 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.
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
Example 1.27. allow_register(basename) usage
...
if (method=="REGISTER") {
if (allow_register("register")) {
save("location");
exit;
} else {
sl_send_reply("403", "Forbidden");
};
};
...
The function returns true if all pairs constructed as described in Section 1.2, “Registration Permissions” 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.
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
Example 1.28. allow_register(allow_file, deny_file) usage
...
if (method=="REGISTER") {
if (allow_register("register.allow", "register.deny")) {
save("location");
exit;
} else {
sl_send_reply("403", "Forbidden");
};
};
...
Returns true if the pair constructed as described in Section 1.3, “URI Permissions” have appropriate permissions according to the configuration files specified by the parameter.
Meaning of the parameter 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.
pvar - Any pseudo-variable defined in Kamailio.
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
Example 1.29. allow_uri(basename, pvar) usage
...
if (allow_uri("basename", "$rt")) { // Check Refer-To URI
t_relay();
};
if (allow_uri("basename", "$avp(i:705)") { // Check URI stored in $avp(i:705)
t_relay();
};
...
Returns true if the address and port given as values of pvar arguments belonging to a group given as group_id argument matches an IP subnet or a DNS domain name found in cached address table.
When matching is done if the argument is an IP address, it is matched with the records from that group that are of type exact IP or subnet. If the argument is not an IP it is tried to be matched with the records that are DNS domain names. No DNS lookup is performed, only strict matching. Cached address table entry containing port value “0” matches any port. The “group_id” argument can be an integer string or a pseudo variable.
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
Example 1.30. allow_address() usage
...
// Check if source address/port is in group 1
if (!allow_address("1", "$si", "$sp")) {
sl_send_reply("403", "Forbidden");
};
// Check address/port stored in AVPs src_adr/src_port is in group 2
$avp(dst_adr) = "sipdomain.com";
$avp(dst_port) = "0";
if (!allow_address("2", "$avp(dst_adr)", "$avp(dst_port)") {
sl_send_reply("403", "Forbidden");
};
...
Equal to “allow_address(group_id, "$si", "$sp")”. If 'group_id' is missing, the function is equal to allow_address("1", "$si", "$sp").
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
Example 1.31. allow_source_address(group_id) usage
...
// Check source address/port of request
if (!allow_source_address("1")) {
sl_send_reply("403", "Forbidden");
};
...
Checks if source address/port is found in cached address or subnet table in any group. If yes, returns that group. If not returns -1. Port value 0 in cached address and group table matches any port.
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
Example 1.32. allow_source_address_group() usage
...
$var(group) = allow_source_address_group();
if ($var(group) != -1) {
# do something with $var(group)
};
...
Checks if address/port is found in cached address or subnet table in any group. If yes, returns that group. If not returns -1. Port value 0 in cached address and group table matches any port. The parameters can be pseudo-variables.
This function can be used from ANY_ROUTE.
Example 1.33. allow_source_address_group() usage
...
$var(group) = allow_address_group("1.2.3.4", "5060");
if ($var(group) != -1) {
# do something with $var(group)
};
...
Checks based either on request's source address and transport
protocol or source address and transport protocol given
in pvar arguments, and From URI of request (or furi_pvar if provided)
if request can be trusted without
authentication. Returns “1” if a match is found
as described in Section 1.5, “Trusted Requests”
and “-1” otherwise. If a match is found
and peer_tag_avp has been defined, adds a
non-NULL tag column value of the
matching peer to AVP peer_tag_avp.
NOTE: source IP is matched using string comparison. Be careful if the IP can have different forms, for a safer alternative for matching IP addresses, look at allow_source_address or allow_address().
Source address, transport protocol and uri given in the arguments must be in string format and they can contain script variables. Valid transport protocol values are (ignoring case) "any", "udp, "tcp", "tls", "ws", "wss" and "sctp".
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
Example 1.34. allow_trusted() usage
...
if (allow_trusted()) {
t_relay();
}
...
if (allow_trusted("$si", "$proto")) {
t_relay();
}
...
if (allow_trusted("$si", "any", "$ai")) {
t_relay();
}
...
Causes the permissions module to re-read the contents of address database table into cache memory. In cache memory the entries are for performance reasons stored in two different tables: address table and subnet table depending on the value of the mask field (IPv6: 64 or smaller, IPv4: 32 or smaller).
Parameters: none
Causes the permissions module to dump the contents of cache memory address table. (Not the subnet table).
Parameters: none
Causes permissions module to dump contents of cache memory subnet table.
Parameters: none
Causes permissions module to dump contents of cache memory domain table.
Parameters: none
Tests if the (URI, Contact) pair is allowed according to allow/deny files. The files must already have been loaded by Kamailio.
Parameters:
basename - Basename from which allow and deny filenames will be created by appending contents of the allow_suffix and deny_suffix parameters.
URI - URI to be tested
Contact - Contact to be tested
Causes the permissions module to re-read the contents of the trusted database table into cache memory.
Parameters: none