The IMS IPSec-Registrar Module

Dragos Vingarzan

FhG Fokus

Jason Penton

Smile Communications

Richard Good

Smile Communications

Carsten Bock

ng-voice GmbH

Tsvetomir Dimitrov


Table of Contents

1. Admin Guide
1. Overview
2. Dependencies
2.1. Kamailio Modules
2.2. External Libraries or Applications
3. Parameters
3.1. ipsec_listen_addr (string)
3.2. ipsec_listen_addr6 (string)
3.3. ipsec_client_port (int)
3.4. ipsec_server_port (int)
3.5. ipsec_max_connections (int)
3.6. ipsec_reuse_server_port (int)
3.7. ipsec_spi_id_start (int)
3.8. ipsec_spi_id_range (int)
3.9. ipsec_preferred_alg (string)
3.10. ipsec_preferred_ealg (string)
4. Functions
4.1. ipsec_create(domain)
4.2. ipsec_forward(domain, flags)
4.3. ipsec_destroy(domain)

List of Examples

1.1. ipsec_listen_addr parameter usage
1.2. ipsec_listen_addr6 parameter usage
1.3. ipsec_client_port parameter usage
1.4. ipsec_server_port parameter usage
1.5. ipsec_max_connections parameter usage
1.6. ipsec_reuse_server_port parameter usage
1.7. ipsec_spi_id_start parameter usage
1.8. ipsec_spi_id_range parameter usage
1.9. ipsec_preferred_alg parameter usage
1.10. ipsec_preferred_ealg parameter usage
1.11. ipsec_create
1.12. ipsec_forward
1.13. ipsec_destroy

Chapter 1. Admin Guide

1. Overview

This module contains methods for IPSec initialisation/deinitialisation related for usage of Kamailio as a Proxy-CSCF.

2. Dependencies

2.1. Kamailio Modules

The Following modules must be loaded before this module:

  • Usrloc PCSCF

  • TM

2.2. External Libraries or Applications

This modules requires the internal IMS library and libmnl for operating with netlink sockets.

3. Parameters

3.1. ipsec_listen_addr (string)

IP address which the Proxy-CSCF will use for incoming/outgoing SIP traffic over IPSec.

Default value is empty string (null) - IPv4 listen interface will not be added

Example 1.1. ipsec_listen_addr parameter usage

...
modparam("ims_ipsec_pcscf", "ipsec_listen_addr", "")
...

3.2. ipsec_listen_addr6 (string)

IPv6 address which the Proxy-CSCF will use for incoming/outgoing SIP traffic over IPSec.

Default value is empty string (null) - IPv6 listen interface will not be added

Example 1.2. ipsec_listen_addr6 parameter usage

...
modparam("ims_ipsec_pcscf", "ipsec_listen_addr6", "")
...

3.3. ipsec_client_port (int)

Port number which will be bound for incoming (server) IPSec traffic.

Default value is 5062.

Example 1.3. ipsec_client_port parameter usage

...
modparam("ims_ipsec_pcscf", "ipsec_client_port", 5062)
...

3.4. ipsec_server_port (int)

Port number which will be bound for incoming (server) IPSec traffic.

Default value is 5063.

Example 1.4. ipsec_server_port parameter usage

...
modparam("ims_ipsec_pcscf", "ipsec_server_port", 5063)
...

3.5. ipsec_max_connections (int)

Maximum simultanious IPSec connections

Default value is 2.

Example 1.5. ipsec_max_connections parameter usage

...
modparam("ims_ipsec_pcscf", "ipsec_max_connections", 10)
...

3.6. ipsec_reuse_server_port (int)

Reuse (1) or not (0) the P-CSCF IPSec information for Re-registration for one UA. When set to 0 - During Re-registration P-CSCF will create new IPSec tunnels. When set to 1 - During Re-registration P-CSCF will reuse the old IPSec tunnels.

Default value is 1.

Example 1.6. ipsec_reuse_server_port parameter usage

...
modparam("ims_ipsec_pcscf", "ipsec_reuse_server_port", 1)
...

3.7. ipsec_spi_id_start (int)

Each IPSec tunnel has a unique system-wide identifier. This and the following option allows to tune the SPIs used by Kamailio in order to avoid collisions with other IPSec useres. If Kamailio is the only process on the system which uses IPSec, don't bother with this option.

Default value is 100.

Example 1.7. ipsec_spi_id_start parameter usage

...
modparam("ims_ipsec_pcscf", "ipsec_spi_id_start", 100)
...

3.8. ipsec_spi_id_range (int)

How many SPIs to be allocated for the process. E.g. if ipsec_spi_id_start = 100 and ipsec_spi_id_range = 1000, SPIs between 100 and 1100 will be used.

Default value is 1000.

Example 1.8. ipsec_spi_id_range parameter usage

...
modparam("ims_ipsec_pcscf", "ipsec_spi_id_range", 1000)
...

3.9. ipsec_preferred_alg (string)

A name of an authentication algorithm which the Proxy-CSCF will prefer when creating IPSec tunnels.

Default value is empty string (null) - the last algorithm in the Sec-Agree header will be used.

Example 1.9. ipsec_preferred_alg parameter usage

...
modparam("ims_ipsec_pcscf", "ipsec_preferred_alg", "hmac-sha-1-96")
...

3.10. ipsec_preferred_ealg (string)

A name of an encrytion algorithm which the Proxy-CSCF will prefer when creating IPSec tunnels.

Default value is empty string (null) - the last algorithm in the Sec-Agree header will be used. Note that the possibility of it being the "null" algorithm is not insignificant.

Example 1.10. ipsec_preferred_ealg parameter usage

...
modparam("ims_ipsec_pcscf", "ipsec_preferred_ealg", "aes-cbc")
...

4. Functions

4.1. ipsec_create(domain)

This function creates IPSec SA and Policy based on the parameters sent in Security-Client header in the REGISTER message. It's called when OK is received. The function also adds Security-Server header to the REGISTER.

Meaning of the parameters is as follows:

  • domain - Logical domain within the registrar. If a database is used then this must be name of the table which stores the contacts.

    flags - bitwise flag: 0x01 - if set - delete unused tunnels before every registration. This is an optional parameter, default value - 0.

Example 1.11. ipsec_create

...
ipsec_create("location");
# or
ipsec_create("location", "1");
...

4.2. ipsec_forward(domain, flags)

The function processes redirects outgoing message via the IPSec tunnel initiated with ipsec_create().

Meaning of the parameters is as follows:

  • domain - Logical domain within the registrar. If a database is used then this must be name of the table which stores the contacts.

    flags - bitwise flag: 0x01 - set force socket for request messages. Useful for ipsec and TCP. 0x02 - reverse search for a contact in the memory. Useful when contact alias is disabled. This is an optional parameter, default value - 0.

Example 1.12. ipsec_forward

...
ipsec_forward("location");
# or
ipsec_forward("location", "1");
...

4.3. ipsec_destroy(domain)

The function destroys IPSec tunnel, created with ipsec_create.

Meaning of the parameters is as follows:

  • domain - Logical domain within the registrar. If a database is used then this must be name of the table which stores the contacts.

Example 1.13. ipsec_destroy

...
ipsec_destroy("location");
...