The authentication header (AH) is an additional header added directly after the IP header to provide packet authentication.
认证报头(AH)是直接添加到IP报头之后的附加报头，以提供包认证。
2
While IP-related authentication certainly raises the bar high enough to keep out all except those of significant skill, it's not something you should ever consider likely to be perfect.
虽然除了那些顶尖高手之外，IP相关认证确实给攻击者设置了足够的障碍，但它也并非近乎完美。
3
The interoperation technology about IP telephony is very concerned now. Some aspects, such as call handling procedures, authentication and authorization procedures, are discussed in this paper.