  The 5G network systems are evolving and have complex network infrastructures.
There is a great deal of work in this area focused on meeting the stringent
service requirements for the 5G networks. Within this context, security
requirements play a critical role as 5G networks can support a range of
services such as healthcare services, financial and critical infrastructures.
3GPP and ETSI have been developing security frameworks for 5G networks. Our
work in 5G security has been focusing on the design of security architecture
and mechanisms enabling dynamic establishment of secure and trusted end to end
services as well as development of mechanisms to proactively detect and
mitigate security attacks in virtualised network infrastructures. The focus of
this paper is on the latter, namely the facilities and mechanisms, and the
design of a security architecture providing facilities and mechanisms to detect
and mitigate specific security attacks. We have developed and implemented a
simplified version of the security architecture using Software Defined Networks
(SDN) and Network Function Virtualisation (NFV) technologies. The specific
security functions developed in this architecture can be directly integrated
into the 5G core network facilities enhancing its security. We describe the
design and implementation of the security architecture and demonstrate how it
can efficiently mitigate specific types of attacks.
