13. Security and Maintenance

Once the sip:provider CE is in production, security and maintenance becomes really important. In this chapter, we’ll go through a set of best practices for any production system.

13.1. Firewalling

The sip:provider CE runs a wide range of services. Some of them need to interact with the user, while some others need to interact with the administrator or with nobody at all. Assuming that we trust the sip:provider CE server for outgoing connections, we’ll focus only on incoming traffic to define the services that need to be open for interaction.

Table 5. Subscribers

Service	Default port	Config option
Customer self care interface	443 TCP	www_csc→apache→port
SIP	5060 UDP, TCP	kamailio→lb→port
SIP over TLS	5061 TCP	kamailio→lb→tls→port + kamailio→lb→tls→enable
RTP	30000-40000 UDP	rtpproxy→minport + rtpproxy→maxport
XCAP	1080 TCP	kamailio→proxy→presence→enable + nginx→xcap_port

Table 6. Administrators

Service	Default port	Config option
SSH/SFTP	22 TCP	NA
Administrator interface	1443 TCP	www_admin→apache→port
Provisioning interfaces	2443 TCP	ossbss→apache→port

To function correctly, the mediaproxy requires an additional iptables rule installed. This rule (with a target of MEDIAPROXY) is automatically installed and removed when the mediaproxy starts and stops, so normally you don’t need to worry about it. However, any 3rd party firewall solution can potentially flush out all existing iptables rules before installing its own, which would leave the system without the required MEDIAPROXY rule and this would lead to decreased performance. It is imperative that any 3rd party firewall solution either leaves this rule untouched, or installs it back into place after flushing all rules out. The complete parameters to install this rule (which needs to go into the INPUT chain of the filter table) are: -p udp -j MEDIAPROXY --id 0

13.2. Password management

The sip:provider CE comes with some default passwords the user should change during the deployment of the system. They have been explained in the previous chapters of this document.

The default password of the system account cdrexport is cdrexport. Although this is a jailed account, it has access to sensitive information, namely the Call Detail Records of all calls. SSH keys should be used to login this user, or alternatively a really strong password should be generated.
The root user in MySQL has no default password. A password should be set using the mysqladmin password command.
The administrative web interface has a default user administrator with password administrator. It should be changed within this interface.


	Many NGCP services use MySQL backend. Users and passwords for these services are created during the installation. These passwords are unique for each installation, and the connections are restricted to localhost. You should not change these users and passwords.

13.3. SSL certificates.

The sip:provider CE provides default, self-signed SSL certificates for SSL connections. These certificates are common for every installation. Before going to production state, the system administrator should provide SSL certificates for the web services. These certificates can either be shared by all web interfaces (provisioning, administrator interface and customer self care interface), or separate ones for each them can be used.

Generate the certificates. The customer self care interface certificate should be signed by a certification authority to avoid browser warnings.
Upload the certificates to the system
Set the path to the new certificates in /etc/ngcp-config/config.yml:
- ossbss→apache→sslcertfile and ossbss→apache→sslcertkeyfile for the provisioning interface.
- www_admin→apache→sslcertfile and www_admin→apache→sslcertkeyfile for the admin interface.
- www_csc→apache→sslcertfile and www_csc→apache→sslcertkeyfile for the customer self care interface.
Apply the configuration changes with ngcpcfg apply.

The sip:provider CE also provides the self-signed SSL certificates for SIP over TLS services. The system administrator should replace them with certificates signed by a trusted certificate authority if he is going to enable it for the production usage (kamailio→lb→tls→enable (disabled by default)).

Generate the certificates.
Upload the certificates to the system
Set the path to the new certificates in /etc/ngcp-config/config.yml:
- kamailio→lb→tls→sslcertfile and kamailio→lb→tls→sslcertkeyfile .
Apply the configuration changes with ngcpcfg apply.

13.4. Backup and recovery

13.4.1. Backup

The sip:provider CE can be integrated with most of the existing backup solutions. While it does not provide any backup system by default, any Debian compatible system can be installed. It’s not the scope of this chapter to go through backup system configuration. We’ll focus on which information needs to be saved.

The minimum set of information to be backed up is:

The database information.

This is the most important data in the system. All subscriber information, billing, CDRs, user preferences etc. are stored in the MySQL server. A periodical dump of all the databases should be performed.

System configuration options

/etc/ngcp-config/config.yml, /etc/ngcp-config/constants.yml, /etc/ngcp-config/network.yml, /etc/mysql/debian.cnf and /etc/mysql/sipwise.cnf files, where your specific system configurations are stored, should be included in the backup as well. Saving the entire /etc/ngcp-config__ folder is a good idea in general.

Optional: Exported CDRs

The directory /home/jail/home/cdrexport contains the exported CDRs the system has generated so far. It depends on your local call data retention policy whether or not to remove these files after exporting them to an external system.

Optional: Custom files

Any custom configurations, like modified templates or additionally implemented services which are not provided by the sip:provider CE

13.4.2. Recovery

In the worst case scenario, when the system needs to be recovered from a total loss, you only need 4 steps to get back online:

Install the sip:provider CE as explained in chapter 2.
Restore config.yml, constants.yml, debian.cnf and sipwise.cnf from the backup, overwriting your local files.
Restore the database dump.
Execute ngcpcfg apply.

13.5. Reset database

To reset database to its original state you can use the script provided by CE: * Execute ngcp-reset-db. It will assign new unique password for the NGCP services and restart all services. IMPORTANT: All existing data will be wiped out without possibility of restoring.

13.6. System requirements and performance

The sip:provider CE is a very flexible system, capable of serving from hundreds to several tens of thousands of subscribers in a single node. The system comes with a default configuration, capable of serving up to 50.000 subscribers in a normal environment. But there is no such thinkg as a normal environment. And the sip:provider CE has sometimes to be tunned for special environments, special hardware requirements or just growing traffic.

In this section some paramenters will be explained to allow the sip:provider CE administrator tune the system requirements for optimum performance.

Table 7. Requirement_options

Option	Default value	Requirement impact
cleanuptools→binlog_days	15	Heavy impact on the harddisk storage needed for mysql logs. It can help to restore the database from backups or restore broken replication.
database→bufferpoolsize	64MB	For test systems or low RAM systems, lowering this setting is one of the most effective ways of releasing RAM. The administrator can check the innodb buffer hit rate on production systems; a hit rate over 99% is desired to avoid bottlenecks.
kamailio→lb→pkg_mem	16	This setting affects the amount of RAM the system will use. Each kamailio-lb worker will have this amount of RAM reserved. Lowering this setting up to 8 will help to release some memory depending on the number of kamailio-lb workers running. This can be a dangerous setting as the lb process could run out of memory. Use with caution.
kamailio→lb→shm_mem	1/16 * Total System RAM	The installer will set this value to 1/16 of the total system RAM. This setting does not change even if the system RAM does so it’s up to the administrator to tune it. It has been calculated that 1024 (1GB) is a good value for 50K subscriber environment. For a test environment, setting the value to 64 should be enough. "Out of memory" messsages in the kamailio log can indicate that this value needs to be raised.
kamailio→lb→tcp_children	8	Number of TCP workers kamailio-lb will spawn per listening socket. The value should be fine for a mixed UDP-TCP 50K subscriber system. Lowering this setting can free some RAM as the number of kamailio processess would decrease. For a test system or a pure UDP subscriber system 2 is a good value. 1 or 2 TCP workers are always needed.
kamailio→lb→tls→enable	yes	Enable or not TLS signaling on the system. Setting this value to "no" will prevent kamailio to spawn TLS listening workers and free some RAM.
kamailio→lb→udp_children	8	See kamailio→lb→tcp_children explanation
kamailio→proxy→children	8	See kamailio→lb→tcp_children explanation. In this case the proxy only listens udp so these children should be enough to handle all the traffic. It could be set to 2 for test systems to lower the requirements.
kamailio→proxy→*_expires		Set the default and the max and min registration interval. The lower it is more REGISTER requests will be handled by the lb and the proxy. It can impact in the network traffic, RAM and CPU usage.
kamailio→proxy→natping_interval	30	Interval for the proxy to send a NAT keepalive OPTIONS message to the nated subscriber. If decreased, this setting will increase the number of OPTIONS requests the proxy needs to send and can impact in the network traffic and the number of natping processes the system needs to run. See kamailio→proxy→natping_processes explanation.
kamailio→proxy→natping_processes	7	Kamailio-proxy will spawn this number of processes to send keepalive OPTIONS to the nated subscribers. Each worker can handle about 250 messages/second (depends on the hardware). Depending the number of nated subscribers and the kamailio→proxy→natping_interval parameter the number of workers may need to be adjusted. The number can be calculated like nated_subscribers/natping_interval/pings_per_second_per_process. For the default options, asuming 50K nated subscribers in the system the parameter value would be 50.000/30/250 = (6,66) 7 workers. 7 is the maximum number of processes kamailio will accept. Raising this value will cause kamailio not to start.
kamailio→proxy→shm_mem	1/16 * Total System RAM	See kamailio→lb→shm_mem explanation.
rateomat→enable	yes	Set this to no if the system shouldn’t perform rating on the CDRs. This will save CPU usage.
rsyslog→external_log	0	If enabled, the system will send the log messages to an external server. Depending on the rsyslog→external_loglevel parameter this can increase dramatically the network traffic.
rsyslog→ngcp_logs_preserve_days	93	This setting will set the number of days ngcp logs under /var/log/ngcp will be kept in disk. Lowering this setting will free a high amount of disk space.