Information
If the XNM-SSL service is configured, the Rate Limit should be set.
Rationale:
JUNOScript can be configured to use SSL transport to prevent the exposure of sensitive data and authentication details on the network. If configured the XNM-SSL service will provide services on port TCP/3220.
An attacker may attempt to open a large number of sessions to the XNM-SSL service to exhaust the routers resources or an authorized user may do so accidently, especially given that the service is designed to allow a scripting interface to JUNOS.
To limit the impact of any such incident, the rate at which new connections to the XNM-SSL service should explicitly limited. Rate Limits are set in terms of the number of connection attempts per minute. Established connections do not count towards this count. A relatively low value of 60 (the equivalent of one attempt per second, sustained over a minute) is recommended, but may not be appropriate for all environments so it is left to the administrator's discretion.
Impact:
If the Rate Limit is exceeded, new connection attempts will be rejected until the new connection rate drops below the configured limit.
Solution
The XNM-SSL Rate Limit can be configured by issuing the following command from the [edit system services xnm-ssl] hierarchy;
[edit system services xnm-ssl]
user@host#set rate-limit <limit>
Where <limit> is the desired Rate Limit measured in Connection Attempts per Minute.
Default Value:
The XNM-SSL Service is disabled by default. When it is first configured the default Rate Limit is 150 connection attempts per second.