IPSEC中IKE协议在LINUX上的实现和研究
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摘要
论文主要研究了IPSEC协议族中，用于建立安全联盟和密钥管理的协议——IKE协议(Internet Key Exchange protocol)的详细内容、实现细节，以及协议本身的优缺点，同时对IKE协议中的积极模式进行实现，并对积极模式的缺点进行改进和有益的探讨。
首先介绍了IPSEC协议。它是针对TCP／IP协议族中缺乏安全保证而开发的，通过在IP层实现来解决安全问题。IPSEC可以分成两大部分，一部分集成到网络协议栈中，对输入输出的IP报文进行机密性、数据完整性和身份验证方面的处理，它们是直接实现网络通信安全的协议；另一部分是为了这些安全协议能正常工作而必须的，即为安全协议进行协商建立安全联盟和加密、验证密钥，这部分称为密钥管理，由IKE和相关的协议来完成。
然后对IKE协议进行介绍。为了更好地理论联系实际，论文结合在LINUX上实现IPSEC的FreeS／WAN工程来加以说明。IKE协议的安全性是整个IPSEC协议安全的基础，因为现代密码学中安全的实现不再依靠算法的保密，而是由密钥的机密性来保证的，如果密钥被窃，整个IPSEC协议都将没有安全性可言。IKE协议正是用来产生密钥并保证密钥交换的安全性的协议，它的强安全性必然导致复杂性，因此对IKE协议细节的掌握就格外重要。
论文的主要工作在于编程实现了IKE协议中的积极模式交换(第一阶段交换)，不仅在实现中体会和把握IKE协议的繁杂和深奥之处，而且，积极模式的实现也可以增强FreeS／WAN工程的功能，以及和其它各种IKE协议实现之间的交互性。
之后，还对积极模式的缺点进行了改进，以克服积极模式本身的易被攻击性，同时也对IKE协议的改进进行了有益的探讨。
最后，为了对IKE协议的完整过程有一个全面的了解，详细介绍了Frees／WAN工程中，IKE协议第二阶段交换的实现细节。
It is mainly studied on the IKE protocol,one of the IPSEC protocols,which is used to build security association and manage keys of encryption/decryption,in this paper.And aggressive mode exchanges,one of the exchanges in IKE protocol, are implemented on Linux box.
First, IPSEC protocol is introduced. It is developed for lacks of security in TCP/IP protocol family,to add security stuff in IP layer. IPSEC can be divided into two parts. One part is used in network protocol statck and process issues about confidentiality,sanity,authentication of data. This part is protocol of security. Another part is do some works for security protocol.such as building securtiy association .It is called key management and done by IKE protocol.
After that , the implementation of IKE on Linux ?FreeS/WAN project is introduced. Security of exchange processes in IKE protocol is the most important stuff in whole IPSEC protocol because the security doesn't depend on the confidential algorithm but on the encryption keys, if keys are exposed to enemy then whole IPSEC security services are no longer secure anymore. So exchange processes are analyzed step by step ,and the resulting problem if not doing so are concerned.
FreeS/WAN also utilize the secure DNS, mechanism of public key distribution ,which is becoming the standard mechanism, and developed the Opportunistic encryption technology that facilitate IPSEC's useage.. IKE daemon needs communicate with kernel to add some security assocation data into sadb, but Linux original kernel doesn't implement such kind of socket, so FreeS/WAN had to extend the Linux kernel.
The implementation of aggressive mode is very important. It makes exchange steps faster, but it also has some disadvantage, such as is vulnerable to DoS attack. Then the method to solve this problem is be developed.
At last, the phase two exchange is introduced for a full grasping about IKE protocol.
首先介绍了IPSEC协议。它是针对TCP／IP协议族中缺乏安全保证而开发的，通过在IP层实现来解决安全问题。IPSEC可以分成两大部分，一部分集成到网络协议栈中，对输入输出的IP报文进行机密性、数据完整性和身份验证方面的处理，它们是直接实现网络通信安全的协议；另一部分是为了这些安全协议能正常工作而必须的，即为安全协议进行协商建立安全联盟和加密、验证密钥，这部分称为密钥管理，由IKE和相关的协议来完成。
然后对IKE协议进行介绍。为了更好地理论联系实际，论文结合在LINUX上实现IPSEC的FreeS／WAN工程来加以说明。IKE协议的安全性是整个IPSEC协议安全的基础，因为现代密码学中安全的实现不再依靠算法的保密，而是由密钥的机密性来保证的，如果密钥被窃，整个IPSEC协议都将没有安全性可言。IKE协议正是用来产生密钥并保证密钥交换的安全性的协议，它的强安全性必然导致复杂性，因此对IKE协议细节的掌握就格外重要。
论文的主要工作在于编程实现了IKE协议中的积极模式交换(第一阶段交换)，不仅在实现中体会和把握IKE协议的繁杂和深奥之处，而且，积极模式的实现也可以增强FreeS／WAN工程的功能，以及和其它各种IKE协议实现之间的交互性。
之后，还对积极模式的缺点进行了改进，以克服积极模式本身的易被攻击性，同时也对IKE协议的改进进行了有益的探讨。
最后，为了对IKE协议的完整过程有一个全面的了解，详细介绍了Frees／WAN工程中，IKE协议第二阶段交换的实现细节。
It is mainly studied on the IKE protocol,one of the IPSEC protocols,which is used to build security association and manage keys of encryption/decryption,in this paper.And aggressive mode exchanges,one of the exchanges in IKE protocol, are implemented on Linux box.
First, IPSEC protocol is introduced. It is developed for lacks of security in TCP/IP protocol family,to add security stuff in IP layer. IPSEC can be divided into two parts. One part is used in network protocol statck and process issues about confidentiality,sanity,authentication of data. This part is protocol of security. Another part is do some works for security protocol.such as building securtiy association .It is called key management and done by IKE protocol.
After that , the implementation of IKE on Linux ?FreeS/WAN project is introduced. Security of exchange processes in IKE protocol is the most important stuff in whole IPSEC protocol because the security doesn't depend on the confidential algorithm but on the encryption keys, if keys are exposed to enemy then whole IPSEC security services are no longer secure anymore. So exchange processes are analyzed step by step ,and the resulting problem if not doing so are concerned.
FreeS/WAN also utilize the secure DNS, mechanism of public key distribution ,which is becoming the standard mechanism, and developed the Opportunistic encryption technology that facilitate IPSEC's useage.. IKE daemon needs communicate with kernel to add some security assocation data into sadb, but Linux original kernel doesn't implement such kind of socket, so FreeS/WAN had to extend the Linux kernel.
The implementation of aggressive mode is very important. It makes exchange steps faster, but it also has some disadvantage, such as is vulnerable to DoS attack. Then the method to solve this problem is be developed.
At last, the phase two exchange is introduced for a full grasping about IKE protocol.
引文
(1) Naganand Doraswamy, Dan Harkins. 《IPSEC新一代因特网安全标准》．机械工业出版社．2000年1月
(2) Bruse Schneier.《应用密码学(协议算法与C源程序)》机械工业出版社．2000年1月
(3) S.Kent, R.Atkinson, IP Encapsulation Security Payload(ESP). RFC2406. November 1998
(4) S.Kent, R.Atkinson, IP Authentication Header. RFC2402. November 1998.
(5) S.Kent, R.Atkinson, Security Architecture for the Internet Protocol. RFC2401. November 1998.
(6) D.Harkins, D.Carrel. The Internet Key Exchange (IKE). RFC2409. November 1998.
(7) D.Maughan, M.Schertler, M.Schneider, J.Turner. Internet Security Association and Key Management Protocol (ISAKMP). RFC2408. November 1998.
(8) D.Piper. The Internet IP Security Domain of Interpretation for ISAKMP. RFC2407. November 1998.
(9) W.Townsley, A.Valencia, A.Rubens etc. Layer Two Tunneling Protocol "L2TP". RFC2661. August 1999
(10) Alessandro Rubini. Virtual Network Interfaces.http://www.linux-mag.com/2000-04/gear_01.html.
(11) Glenn Herrin. Linux IP Networking. A Guide to the Implementation and Modification of the LinuxProtocol Stack. May 31 2000. http://kernelnewbies.org/documents/ipnetworking/linuxipnetworking.html
(12) D.McDonald, C.Metz, B.Phan. PF_KEY Key Management API,Version 2. RFC2367. July 1998.
(13) W.Richard Stevens. 《UNIX网络编程(第1卷)》(第2版)．清华大学出版社．1999年7月．
(2) Bruse Schneier.《应用密码学(协议算法与C源程序)》机械工业出版社．2000年1月
(3) S.Kent, R.Atkinson, IP Encapsulation Security Payload(ESP). RFC2406. November 1998
(4) S.Kent, R.Atkinson, IP Authentication Header. RFC2402. November 1998.
(5) S.Kent, R.Atkinson, Security Architecture for the Internet Protocol. RFC2401. November 1998.
(6) D.Harkins, D.Carrel. The Internet Key Exchange (IKE). RFC2409. November 1998.
(7) D.Maughan, M.Schertler, M.Schneider, J.Turner. Internet Security Association and Key Management Protocol (ISAKMP). RFC2408. November 1998.
(8) D.Piper. The Internet IP Security Domain of Interpretation for ISAKMP. RFC2407. November 1998.
(9) W.Townsley, A.Valencia, A.Rubens etc. Layer Two Tunneling Protocol "L2TP". RFC2661. August 1999
(10) Alessandro Rubini. Virtual Network Interfaces.http://www.linux-mag.com/2000-04/gear_01.html.
(11) Glenn Herrin. Linux IP Networking. A Guide to the Implementation and Modification of the LinuxProtocol Stack. May 31 2000. http://kernelnewbies.org/documents/ipnetworking/linuxipnetworking.html
(12) D.McDonald, C.Metz, B.Phan. PF_KEY Key Management API,Version 2. RFC2367. July 1998.
(13) W.Richard Stevens. 《UNIX网络编程(第1卷)》(第2版)．清华大学出版社．1999年7月．