default_allow_file (string)
default_deny_file (string)
check_all_branches (integer)
allow_suffix (string)
deny_suffix (string)
max_rule_files (int)
safe_file_load (int)
db_url (string)
db_mode (int)
ipmatch_table (string)
declare_ipset (string)
allow_routing()
allow_routing(basename)
allow_routing(allow_file, deny_file)
allow_register(basename)
allow_register(allow_file, deny_file)
allow_refer_to(basename)
allow_refer_to(allow_file, deny_file)
ipmatch (string/AVP/select, [avp])
ipmatch_onsend (string)
ipmatch_filter (unsigned int)
ip_is_trusted(ip_set, ip)
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.
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, “Call Routing”. 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, “Call Routing”.
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.
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.
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. Set default_allow_file parameter
...
modparam("permissions", "default_allow_file", "/etc/permissions.allow")
...
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 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.
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 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".
Module initialization fails in case of a missing config file if safe_file_load is true.
Default value is 0 (false).
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.
Name of the table containing ipmatch entries.
Default value is "ipmatch".
Returns true if all pairs constructed as described in Section 1.1.1, “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.
Returns true if all pairs constructed as described in Section 1.1.1, “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.
Returns true if all pairs constructed as described in Section 1.1.1, “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.
Example 8. 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 1.1.2, “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.
Example 9. allow_register(basename) usage
...
if (method=="REGISTER") {
if (allow_register("register")) {
save("location");
break;
} else {
sl_send_reply("403", "Forbidden");
};
};
...
The function returns true if all pairs constructed as described in Section 1.1.2, “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.
Example 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");
};
};
...
The function returns true if all pairs constructed as described in Section 1.1.2, “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.
Example 11. allow_register(basename) usage
...
if (method=="REGISTER") {
if (allow_register("register")) {
save("location");
break;
} else {
sl_send_reply("403", "Forbidden");
};
};
...
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 12. allow_register(allow_file, deny_file) usage
...
if (method=="REFER") {
if (allow_register("refer.allow", "refer.deny")) {
...
} else {
sl_send_reply("403", "Forbidden");
};
};
...
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.
Meaning of the parameters is as follows:
string/AVP/select - File containing allow rules.
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. "$myavp"
select call:
e.g. "@via[0].host"
The second parameter is optional, it is used to set an AVP value from the database. Suitable for assigning logical identifiers to gateways.
Note that IPv6 addresses must be enclosed in square brackets in case of port is defined: [1111:2222::3333]:5060
ipmatch() function replacement for onsend_route block.
The function accepts only string parameter, because even AVP reading is unsafe in onsend_route.
Meaning of the parameter:
"dst":
the destination address is used
"ruri":
the ip:port pair is extracted from the Request URI
The function can be used for example to catch unauthorized requests going to gateways: Use a flag to mark the call as PSTN either in request or in failure_route, and do not touch it in onreply_route. See the examples below.
Entries in the database can be marked to group the different kind of network elements. The function sets the filter which is used on the mark while comparing the IP addresses. The mark must be the power of 2 in the database!
Note that ipmatch() and ipmatch_onsend() functions reset the filter!
Example 13. ipmatch_filter (unsigned int) usage
+-----------------+-------------------+------+------+
| ip | avp_val | mark | flag |
+-----------------+-------------------+------+------+
| 1111:2222::1001 | first_gw | 1 | 1 |
| 10.38.2.10:5060 | second_gw | 1 | 1 |
| 10.0.0.10 | first_peering | 2 | 1 |
+-----------------+-------------------+------+------+
route[0] {
# is this a request from a GW?
ipmatch_filter("1");
if (ipmatch("src", "$gw_id")) {
# yes, it is from a GW
...
} else {
# is this a request from a peering partner?
ipmatch_filter("2");
if (ipmatch("src", "$peering_id")) {
# yes, it is from a peering partner
...
};
}
...
# request goes to PSTN
setflag(PSTN);
}
onsend_route[0] {
if (method == "INVITE" && (!isflagset(PSTN))) {
# is this a request to a GW?
ipmatch_filter("1");
if (ipmatch_onsend("dst")) {
# request is not marked with PSTN flag, but it goes to a gateway
drop;
}
}
...
}
The function returns true if ip is contained in ip_set. Both IPv4 and IPv6 are supported.
Meaning of the parameters is as follows:
ip_set is identified by comma/space/semicolon delimited list of IP addresses or subnet masks. The subnet mask is written in IP_slash_number form or as IP. If the mask is not mentioned then default value is taken, the default value is number of bits of particular IP address, i.e. 32 in case of IPv4, 128 in case of IPv6.
Besides list also ip set identifier declared by declare_ipset may
be provided. In this case ip is checked against set maintainded by RPC commands.
ip to test. Besides direct address in string form there are extra identifiers to force IP related to current message: Source, Destination, Received. Note that only the first character is essential.
Example 14. ip_is_trusted usage
modparam("permissions", "declare_ipset", "my_ipset1");
modparam("permissions", "declare_ipset", "my_ipset2=127.0.0.0/24;10.0.0.0/255.255.255.0");
route[TT2] {
if (ip_is_trusted("$net", "$ip")) {
xlog("L_E", "'%$ip' - TRUE\n");
} else {
xlog("L_E", "'%$ip' - FALSE\n");
}
}
route[TT1] {
xlog("L_E", "Testing netmask '%$net'\n");
$ip = "s"; # source address
route(TT2);
$ip = "127.0.0.1";
route(TT2);
$ip = "127.0.0.2";
route(TT2);
$ip = "10.0.0.1";
route(TT2);
$ip = "11.0.0.1";
route(TT2);
$ip = "172.1.8.1";
route(TT2);
$ip = "192.168.1.1";
route(TT2);
$ip = "192.168.1.255";
route(TT2);
$ip = "192.168.2.1";
route(TT2);
$ip = "192.168.3.1";
route(TT2);
$ip = "192.168.4.97";
route(TT2);
$ip = "192.168.4.100";
route(TT2);
$ip = "[0:2:4:A:B:D:E:F301]";
route(TT2);
$ip = "[0:2:4:A:B:D:E:F401]";
route(TT2);
$ip = "[0:0:0:0:0:0:0:0]";
route(TT2);
}
route[TEST] {
$net = "0.0.0.0 128.2.3.4/1 127.0.128.16 [0:2:4:A:B:D:E:F301]";
route(TT1);
$net = "255.255.255.255/0"; # all IPv4 addresses, dentical to 0.0.0.0/0
route(TT1);
$net = "127.0.0.1/255.255.255.0";
route(TT1);
$net = "10.0.0.0/8"; # All type A addresses
route(TT1);
$net = "192.168.1.0/24";
route(TT1);
$net = "192.168.4.96/27";
route(TT1);
$net = "192.168.1.1/32"; # only one IP matches
route(TT1);
$net = "192.168.1.0/24,192.168.2.0/24";
route(TT1);
$net = "192.168.1.0/24,192.168.2.0/24,127.0.0.1/31";
route(TT1);
$net = "[0:0:0:0:0:0:0:0]/0"; # all IPv6 addresses
route(TT1);
$net = "[0:2:4:A:B:D:E:f300]/120";
route(TT1);
$net = "my_ipset1";
route(TT1);
}
# the result is:
Testing netmask '0.0.0.0 128.2.3.4/1 127.0.128.16 [0:2:4:A:B:D:E:F301]'
's' - FALSE
'127.0.0.1' - FALSE
'127.0.0.2' - FALSE
'10.0.0.1' - FALSE
'11.0.0.1' - FALSE
'172.1.8.1' - TRUE
'192.168.1.1' - TRUE
'192.168.1.255' - TRUE
'192.168.2.1' - TRUE
'192.168.3.1' - TRUE
'192.168.4.97' - TRUE
'192.168.4.100' - TRUE
'[0:2:4:A:B:D:E:F301]' - TRUE
'[0:2:4:A:B:D:E:F401]' - FALSE
'[0:0:0:0:0:0:0:0]' - FALSE
Testing netmask '255.255.255.255/0'
's' - TRUE
'127.0.0.1' - TRUE
'127.0.0.2' - TRUE
'10.0.0.1' - TRUE
'11.0.0.1' - TRUE
'172.1.8.1' - TRUE
'192.168.1.1' - TRUE
'192.168.1.255' - TRUE
'192.168.2.1' - TRUE
'192.168.3.1' - TRUE
'192.168.4.97' - TRUE
'192.168.4.100' - TRUE
'[0:2:4:A:B:D:E:F301]' - FALSE
'[0:2:4:A:B:D:E:F401]' - FALSE
'[0:0:0:0:0:0:0:0]' - FALSE
Testing netmask '127.0.0.1/24'
's' - FALSE
'127.0.0.1' - TRUE
'127.0.0.2' - TRUE
'10.0.0.1' - FALSE
'11.0.0.1' - FALSE
'172.1.8.1' - FALSE
'192.168.1.1' - FALSE
'192.168.1.255' - FALSE
'192.168.2.1' - FALSE
'192.168.3.1' - FALSE
'192.168.4.97' - FALSE
'192.168.4.100' - FALSE
'[0:2:4:A:B:D:E:F301]' - FALSE
'[0:2:4:A:B:D:E:F401]' - FALSE
'[0:0:0:0:0:0:0:0]' - FALSE
Testing netmask '10.0.0.0/8'
's' - FALSE
'127.0.0.1' - FALSE
'127.0.0.2' - FALSE
'10.0.0.1' - TRUE
'11.0.0.1' - FALSE
'172.1.8.1' - FALSE
'192.168.1.1' - FALSE
'192.168.1.255' - FALSE
'192.168.2.1' - FALSE
'192.168.3.1' - FALSE
'192.168.4.97' - FALSE
'192.168.4.100' - FALSE
'[0:2:4:A:B:D:E:F301]' - FALSE
'[0:2:4:A:B:D:E:F401]' - FALSE
'[0:0:0:0:0:0:0:0]' - FALSE
Testing netmask '192.168.1.0/24'
's' - FALSE
'127.0.0.1' - FALSE
'127.0.0.2' - FALSE
'10.0.0.1' - FALSE
'11.0.0.1' - FALSE
'172.1.8.1' - FALSE
'192.168.1.1' - TRUE
'192.168.1.255' - TRUE
'192.168.2.1' - FALSE
'192.168.3.1' - FALSE
'192.168.4.97' - FALSE
'192.168.4.100' - FALSE
'[0:2:4:A:B:D:E:F301]' - FALSE
'[0:2:4:A:B:D:E:F401]' - FALSE
'[0:0:0:0:0:0:0:0]' - FALSE
Testing netmask '192.168.4.96/27'
's' - FALSE
'127.0.0.1' - FALSE
'127.0.0.2' - FALSE
'10.0.0.1' - FALSE
'11.0.0.1' - FALSE
'172.1.8.1' - FALSE
'192.168.1.1' - FALSE
'192.168.1.255' - FALSE
'192.168.2.1' - FALSE
'192.168.3.1' - FALSE
'192.168.4.97' - TRUE
'192.168.4.100' - TRUE
'[0:2:4:A:B:D:E:F301]' - FALSE
'[0:2:4:A:B:D:E:F401]' - FALSE
'[0:0:0:0:0:0:0:0]' - FALSE
Testing netmask '192.168.1.1/32'
's' - FALSE
'127.0.0.1' - FALSE
'127.0.0.2' - FALSE
'10.0.0.1' - FALSE
'11.0.0.1' - FALSE
'172.1.8.1' - FALSE
'192.168.1.1' - TRUE
'192.168.1.255' - FALSE
'192.168.2.1' - FALSE
'192.168.3.1' - FALSE
'192.168.4.97' - FALSE
'192.168.4.100' - FALSE
'[0:2:4:A:B:D:E:F301]' - FALSE
'[0:2:4:A:B:D:E:F401]' - FALSE
'[0:0:0:0:0:0:0:0]' - FALSE
Testing netmask '192.168.1.0/24,192.168.2.0/24'
's' - FALSE
'127.0.0.1' - FALSE
'127.0.0.2' - FALSE
'10.0.0.1' - FALSE
'11.0.0.1' - FALSE
'172.1.8.1' - FALSE
'192.168.1.1' - TRUE
'192.168.1.255' - TRUE
'192.168.2.1' - TRUE
'192.168.3.1' - FALSE
'192.168.4.97' - FALSE
'192.168.4.100' - FALSE
'[0:2:4:A:B:D:E:F301]' - FALSE
'[0:2:4:A:B:D:E:F401]' - FALSE
'[0:0:0:0:0:0:0:0]' - FALSE
Testing netmask '192.168.1.0/24,192.168.2.0/24,127.0.0.1/31'
's' - FALSE
'127.0.0.1' - TRUE
'127.0.0.2' - FALSE
'10.0.0.1' - FALSE
'11.0.0.1' - FALSE
'172.1.8.1' - FALSE
'192.168.1.1' - TRUE
'192.168.1.255' - TRUE
'192.168.2.1' - TRUE
'192.168.3.1' - FALSE
'192.168.4.97' - FALSE
'192.168.4.100' - FALSE
'[0:2:4:A:B:D:E:F301]' - FALSE
'[0:2:4:A:B:D:E:F401]' - FALSE
'[0:0:0:0:0:0:0:0]' - FALSE
Testing netmask '[0:0:0:0:0:0:0:0]/0'
's' - FALSE
'127.0.0.1' - FALSE
'127.0.0.2' - FALSE
'10.0.0.1' - FALSE
'11.0.0.1' - FALSE
'172.1.8.1' - FALSE
'192.168.1.1' - FALSE
'192.168.1.255' - FALSE
'192.168.2.1' - FALSE
'192.168.3.1' - FALSE
'192.168.4.97' - FALSE
'192.168.4.100' - FALSE
'[0:2:4:A:B:D:E:F301]' - TRUE
'[0:2:4:A:B:D:E:F401]' - TRUE
'[0:0:0:0:0:0:0:0]' - TRUE
Testing netmask '[0:2:4:A:B:D:E:f300]/120'
's' - FALSE
'127.0.0.1' - FALSE
'127.0.0.2' - FALSE
'10.0.0.1' - FALSE
'11.0.0.1' - FALSE
'172.1.8.1' - FALSE
'192.168.1.1' - FALSE
'192.168.1.255' - FALSE
'192.168.2.1' - FALSE
'192.168.3.1' - FALSE
'192.168.4.97' - FALSE
'192.168.4.100' - FALSE
'[0:2:4:A:B:D:E:F301]' - TRUE
'[0:2:4:A:B:D:E:F401]' - FALSE
'[0:0:0:0:0:0:0:0]' - FALSE
}
Some functionality may be controled using RPC commands.
ipmatch.reload - Reloads the cached ipmatch table. The original table remains active in case of any failure.
ipset.clean(ipset_name) - Clear all entries in "pending" ipset.
ipset.add(ipset_name, ip, netmask) - Add ip and mask into ipset. IPv6 should should be enclosed in brackets. Netmask may be identified as number or in IP form. Note that number requires leading slash, e.g. "/24" or "255.255.255.0".
ipset.commit(ipset_name) - Makes
pending ip set usable by ip_is_trusted.
Pending ip set is cleared.
ipset.list() - List declared ip sets.
ipset.print(ipset_name, pending) - Dump
ipset trees. If pending non zero then
pending ipset is dumped.