References:
1. S.K.Ganiev, M.M.Karimov va K.A. Toshev, “Axborot xavfsizligi,” Toshkent, 2008.
2. RFC 4026, L. Andersson, T. Madsen and A.B. Acreo, "Provider-Provided Virtual Private Network (VPN) Terminology", March 2005.
3. SAFE “VPN IPSec virtual private networks,” Cisco Systems, Inc., 2004 y.
4. D. Dyuks, and R. Pereyra, " ISAKMP configuration method," draftietf-ipsec-isakmp-cfg-03.txt.