CN103685168B - A kind of inquiry request method of servicing of DNS recursion server - Google Patents
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Abstract
本发明公开了一种DNS递归服务器的查询请求服务方法，属于网络技术领域。本方法为：1)将DNS递归服务器的缓存划分可信缓存区和不可信缓存区；2)递归服务器收到一查询请求后，在可信缓存区的资源记录中查找是否有匹配的资源；如果有，则将匹配资源记录返回给查询端；如果没有，则向权威服务器发起查询请求；3)递归服务器监测该查询请求的响应数据包到达率；4)如果响应数据包到达率超过可信门限，则递归服务器将该查询请求的响应数据包置于不可信缓存区；如果未超过该可信门限，则重新向权威服务器发起查询请求，将得到的DNS资源记录发送给查询端，并将其添加到可信缓存区。本发明减小了缓存中毒的可能性，保证了查询的效率。
The invention discloses a query request service method of a DNS recursive server, which belongs to the technical field of networks. The method is as follows: 1) dividing the cache of the DNS recursive server into a trusted cache area and an untrusted cache area; 2) after the recursive server receives a query request, it searches whether there is a matching resource in the resource record of the trusted cache area; If there is, the matching resource record is returned to the query end; if not, a query request is initiated to the authoritative server; 3) the recursive server monitors the arrival rate of the response data packet of the query request; 4) if the arrival rate of the response data packet exceeds the trusted threshold, the recursive server will place the response packet of the query request in the untrusted cache; if the trusted threshold is not exceeded, the recursive server will re-initiate the query request to the authoritative server, send the obtained DNS resource record to the query end, and It is added to the trusted cache. The invention reduces the possibility of cache poisoning and ensures query efficiency.
Description
技术领域 technical field
本发明涉及一种DNS递归服务器的查询请求服务方法，属于计算机网络技术领域。The invention relates to a query request service method of a DNS recursive server, belonging to the technical field of computer networks.
背景技术 Background technique
互联网域名系统(Domain Name System，DNS)的主要实体包括提供解析查询服务的递归服务器和提供权威应答服务的权威服务器。其查询过程如图1所示。具体步骤为：The main entities of the Internet Domain Name System (Domain Name System, DNS) include recursive servers that provide resolution query services and authoritative servers that provide authoritative answer services. The query process is shown in Figure 1. The specific steps are:
1)当终端用户希望访问www.sina.com时，向递归服务器发送DNS查询请求消息；1) When the end user wishes to visit www.sina.com, send a DNS query request message to the recursive server;
2)如果递归服务器的缓存中完全没有该域名的相关信息(假设既没有com的权威服务器地址，也没有sina.com的权威服务器地址)，递归服务器便需要向根服务器发起查询过程，从而获知com权威服务器的地址；2) If there is no relevant information about the domain name in the cache of the recursive server (assuming that there is neither the authoritative server address of com nor the authoritative server address of sina.com), the recursive server needs to initiate a query process to the root server to learn that com the address of the authoritative server;
3)递归服务器接着向com权威服务器发送查询消息，于是获知到sina.com权威服务器的地址信息；3) The recursive server then sends a query message to the com authoritative server, and thus obtains the address information of the sina.com authoritative server;
4)通过向sina.com权威服务器的继续查询，递归服务器最终获知了www.sina.com的地址；4) By continuing to query the authoritative server of sina.com, the recursive server finally obtains the address of www.sina.com;
5)递归服务器将查询所得到的资源记录返回给客户端，并将该记录存储在缓存中。当其他终端用户向该递归服务器查询www.sina.com时，递归服务器直接在缓存中查找匹配的资源记录就能进行及时响应。而终端用户也可以经由该地址信息访问对应网络资源。5) The recursive server returns the resource record obtained by the query to the client, and stores the record in the cache. When other terminal users query www.sina.com from the recursive server, the recursive server can directly search the cache for matching resource records to respond in time. And the terminal user can also access the corresponding network resources through the address information.
在上述查询过程中，递归服务器向任何一个权威服务器发送查询消息后，如果对应的伪造响应数据包能够在正确响应数据包到达之前被递归服务器接收，且匹配了递归服务器发送出的查询数据包的UDP端口号和数据包ID，递归服务器就会把错误的权威资源记录缓存起来，从而造成缓存中毒。当后续用户查询该域名时，都被引导到错误或恶意的站点。In the above query process, after the recursive server sends a query message to any authoritative server, if the corresponding forged response data packet can be received by the recursive server before the correct response data packet arrives, and matches the query data packet sent by the recursive server UDP port number and packet ID, the recursive server will cache the wrong authoritative resource records, thus causing cache poisoning. When subsequent users query the domain name, they are directed to the wrong or malicious site.
如何识别和避免递归服务器缓存不可信的或伪造的响应信息，以尽量减小DNS递归服务器缓存中毒的可能性是一亟待解决的技术问题。How to identify and avoid untrustworthy or forged response information cached by the recursive server so as to minimize the possibility of cache poisoning of the DNS recursive server is a technical problem to be solved urgently.
发明内容 Contents of the invention
针对现有技术中存在的技术问题，本发明的目的在于提供一种DNS递归服务器的查询请求服务方法。本发明提出将DNS递归服务器的缓存划分成两个部分：可信缓存区和不可信缓存区。其中可信缓存区是通过正常查询而缓存的正确DNS资源记录；不可信缓存区是由于DNS递归服务器通过监测DNS流量对某些响应产生怀疑而对应的资源记录。可信缓存区的使用依照递归服务器通常使用缓存数据的规则，而不可信缓存区的数据不能直接用于回复客户端。只有当监测结果回落到递归服务器选择的可信门限以下，才对不可信缓存区的资源记录重新发起查询过程，并将对应的响应添加到可信缓存区。Aiming at the technical problems existing in the prior art, the purpose of the present invention is to provide a DNS recursive server query request service method. The present invention proposes to divide the cache of the DNS recursive server into two parts: a trusted cache area and an untrusted cache area. The trusted cache area is the correct DNS resource record cached through normal query; the untrusted cache area is the corresponding resource record because the DNS recursive server suspects certain responses by monitoring DNS traffic. Trusted caches are used in accordance with the rules that recursive servers usually use cached data, and data in untrusted caches cannot be used directly to reply to clients. Only when the monitoring result falls below the credible threshold selected by the recursive server, will the query process be re-initiated for the resource records in the untrusted cache, and the corresponding response will be added to the credible cache.
本发明的技术方案为：Technical scheme of the present invention is:
一种DNS递归服务器的查询请求服务方法，其步骤为：A query request service method for a DNS recursive server, the steps of which are:
1)将DNS递归服务器的缓存划分可信缓存区和不可信缓存区；其中，可信缓存区用于缓存可信的DNS资源记录，不可信缓存区是用于存储可疑查询请求对应的DNS资源记录；1) The cache of the DNS recursive server is divided into a trusted cache area and an untrusted cache area; wherein, the trusted cache area is used to cache trusted DNS resource records, and the untrusted cache area is used to store DNS resources corresponding to suspicious query requests Record;
2)递归服务器收到一查询请求后，在可信缓存区的资源记录中查找是否有匹配的资源；如果有，则将匹配资源记录返回给查询端；如果没有，则向权威服务器发起查询请求；2) After the recursive server receives a query request, it searches the resource record in the trusted cache to see if there is a matching resource; if there is, it returns the matching resource record to the query end; if not, it initiates a query request to the authoritative server ;
3)递归服务器监测该查询请求的响应数据包到达率；所述响应数据包到达率为设定时间长度内接收到的针对同一查询请求的响应数据包；3) the recursive server monitors the response data packet arrival rate of the query request; the response data packet arrival rate is received within the set time length for the response data packets of the same query request;
4)如果该查询请求的响应数据包到达率超过预设可信门限，则递归服务器将该查询请求的响应数据包置于不可信缓存区；如果该查询请求的响应数据包到达率未超过该预设可信门限，则重新向权威服务器发起查询请求，将得到的DNS资源记录发送给查询端，并将其作为一可信的DNS资源记录添加到可信缓存区。4) If the arrival rate of the response packet of the query request exceeds the preset trusted threshold, the recursive server places the response packet of the query request in an untrusted buffer; if the arrival rate of the response packet of the query request does not exceed the If the trusted threshold is preset, a query request is re-initiated to the authoritative server, the obtained DNS resource record is sent to the query end, and it is added to the trusted cache as a trusted DNS resource record.
进一步的，如果该查询请求的响应数据包到达率超过预设可信门限时，递归服务器收到其他查询端发出的与该查询请求相同的查询请求2，且该查询请求2的响应数据包到达率未超过该预设可信门限，则递归服务器针对该查询请求2向权威服务器发起查询请求。Further, if the arrival rate of the response packet of the query request exceeds the preset credible threshold, the recursive server receives the same query request 2 as the query request from other query terminals, and the response packet of the query request 2 arrives rate does not exceed the preset credible threshold, the recursive server initiates a query request to the authoritative server for the query request 2.
进一步的，如果某查询请求的响应数据包到达率超过预设可信门限，则所述递归服务器通过根据该查询请求发送出去的查询消息中的目的IP地址，确定出缓存中毒攻击源。Further, if the arrival rate of response data packets of a certain query request exceeds a preset credible threshold, the recursive server determines the source of the cache poisoning attack through the destination IP address in the query message sent by the query request.
进一步的，所述递归服务器实时监测查询请求的响应数据包到达率。Further, the recursive server monitors the arrival rate of response data packets of query requests in real time.
本发明具有如下特点：The present invention has following characteristics:
1)通过划分缓存区域实现对不可信资源记录的隔离；1) Realize the isolation of untrusted resource records by dividing the cache area;
2)同一个查询请求的响应数据包到达率过大时，递归服务器认为有缓存中毒攻击发生，从而将接收到的响应判定为不可信；2) When the arrival rate of response data packets for the same query request is too large, the recursive server considers that a cache poisoning attack has occurred, and thus determines the received response as untrustworthy;
3)通过把不可信缓存区中资源记录的重查结果填充到可信缓存区，保证了递归服务器通过使用缓存提高查询处理效率的目的。3) By filling the recheck results of the resource records in the untrusted cache area into the trusted cache area, the recursive server can ensure the purpose of improving query processing efficiency by using the cache.
与现有技术相比，本发明的积极效果为：Compared with prior art, positive effect of the present invention is:
本发明通过将缓存区域划分可信缓存区和不可信缓存区，实现对不可信资源记录的隔离；从而避免递归服务器缓存不可信的或伪造的响应信息，减小了DNS递归服务器缓存中毒的可能性，保证了递归服务器查询处理的效率。The present invention realizes the isolation of untrustworthy resource records by dividing the cache area into a credible cache area and an untrustworthy cache area; thereby avoiding recursive servers from caching untrustworthy or forged response information and reducing the possibility of DNS recursive server cache poisoning It ensures the efficiency of recursive server query processing.
附图说明 Description of drawings
图1为现有DNS查询流程图；Fig. 1 is the flow chart of existing DNS query;
图2为本发明的方法流程图。Fig. 2 is a flow chart of the method of the present invention.
具体实施方式 detailed description
本发明中递归服务器的处理流程如图2所示。The processing flow of the recursive server in the present invention is shown in FIG. 2 .
1)递归服务器收到一查询请求后，先在可信缓存的资源记录中查找是否有匹配的资源；递归服务器首先希望通过可信缓存的查询，将匹配响应尽快返回给用户，从而提高查询效率(在没有发现攻击情况下，所有查询到的结果都会保存到可信缓存中，比如图1例子中com的权威服务器地址、sina.com的权威服务器地址和www.sina.com的地址。当检测到攻击时，接收到的响应信息就存储到不可信区中。)；如果没有，则向权威服务器发起查询请求，当该查询请求对应的响应数据包到达率超过预设的门限，就认为该缓存正遭受毒化攻击，中毒源就是递归服务器发送出去的查询消息的目的IP地址。比如当缓存中毒攻击源向递归服务器发送域名如xxx.yyy.cn的查询请求时，其未在可信缓存中找到对应资源记录的递归服务器随即向权威服务器发起查询过程；权威服务器的主要功能就是维护DNS数据。“响应数据包到达率”就是通过统计一定时间内接收到的针对同一查询请求的响应数据包。1) After the recursive server receives a query request, it first searches for matching resources in the resource records of the trusted cache; the recursive server first hopes to return the matching response to the user as soon as possible through the query of the trusted cache, thereby improving query efficiency (In the case that no attack is found, all query results will be saved in the trusted cache, such as the authoritative server address of com, the authoritative server address of sina.com, and the address of www.sina.com in the example in Figure 1. When detecting When an attack occurs, the received response information is stored in the untrusted zone.); if not, a query request is initiated to the authoritative server, and when the arrival rate of the response data packet corresponding to the query request exceeds the preset threshold, the The cache is under poisoning attack, and the poisoning source is the destination IP address of the query message sent by the recursive server. For example, when the cache poisoning attack source sends a query request for a domain name such as xxx.yyy.cn to the recursive server, the recursive server that does not find the corresponding resource record in the trusted cache immediately initiates a query process to the authoritative server; the main function of the authoritative server is Maintain DNS data. The "response data packet arrival rate" is to count the response data packets received within a certain period of time for the same query request.
2)为了对该递归服务器进行毒化，攻击源向递归服务器发送大批量的伪造响应消息，以期匹配递归服务器向权威服务器发送DNS查询消息的UDP端口号和数据包ID；2) In order to poison the recursive server, the attack source sends a large number of forged response messages to the recursive server, in order to match the UDP port number and packet ID of the DNS query message sent by the recursive server to the authoritative server;
3)如果递归服务器通过同一个查询请求的响应数据包到达率判定该响应的不可信程度，那么如果响应数据包到达率超过预设门限后，递归服务器将接收到的匹配响应消息置于不可信缓存区(为对本发明技术方案进行清晰展示，本发明以同一个查询请求的响应数据包到达率判定该响应的不可信程度，但本发明也可以支持其他判定规则)；3) If the recursive server determines the untrustworthiness of the response through the arrival rate of the response data packet of the same query request, then if the arrival rate of the response data packet exceeds the preset threshold, the recursive server will place the received matching response message as untrustworthy Buffer area (in order to clearly demonstrate the technical solution of the present invention, the present invention judges the degree of unreliability of the response with the arrival rate of the response packet of the same query request, but the present invention can also support other judgment rules);
4)如果递归服务器此时接收到其他客户端发起的对应该毒化缓存的查询请求，且其他客户端发出的请求的对应响应回落到可信门限以下，则递归服务器不采用不可信缓存区中的数据，并重新向权威服务器发起查询过程予以回复；4) If the recursive server receives query requests from other clients corresponding to the poisoned cache at this time, and the corresponding responses to the requests sent by other clients fall below the trusted threshold, the recursive server does not use the cache in the untrusted cache. data, and re-initiate the query process to the authoritative server to reply;
5)直到递归服务器接收到的该查询请求的响应数据包到达率回落到可信门限以下，递归服务器认为攻击已经结束，于是重新发起查询过程，并将响应中的资源记录添加到可信区，以实现对后续查询的快速响应。比如：如有查询请求消息1、2，对应查询消息1，有大量伪造响应，对应查询消息2，还是有大量伪造响应，那么递归服务器就认为查询1和查询2都是伪造的查询，是毒化缓存所用，而不予以响应。但是如果这两个查询对应的响应在可信门限以下，那么递归服务器就认为这是个正常的查询，从而向权威服务器发起查询，然后将响应中的资源记录添加到可信区，以实现对后续查询的快速响应。5) Until the arrival rate of the response packet of the query request received by the recursive server falls below the credible threshold, the recursive server thinks that the attack has ended, so it re-initiates the query process, and adds the resource record in the response to the trusted zone, To enable a quick response to subsequent inquiries. For example: if there are query request messages 1 and 2, corresponding to query message 1, there are a large number of forged responses, and corresponding to query message 2, there are still a large number of forged responses, then the recursive server thinks that query 1 and query 2 are both forged queries, which is poisoning Used by caches, not for responses. However, if the responses corresponding to these two queries are below the trusted threshold, the recursive server considers this a normal query, and initiates a query to the authoritative server, and then adds the resource record in the response to the trusted zone, so as to realize subsequent Quick response to inquiries.
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| CN108494891A (en) * | 2018-02-28 | 2018-09-04 | 网宿科技股份有限公司 | A kind of domain name analytic method, server and system |
| CN112543215B (en) * | 2019-09-23 | 2024-06-21 | 北京国双科技有限公司 | Access request processing method, system, device, storage medium and electronic equipment |
| CN113742783A (en) * | 2020-05-27 | 2021-12-03 | 伏羲科技(菏泽)有限公司 | Domain name data processing method and device, server and storage medium |
| CN111698345B (en) * | 2020-06-10 | 2022-09-20 | 山东伏羲智库互联网研究院 | Domain name query method, recursive server and storage medium |
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