MassDNS是一种简单的高性能DNS存根解析器，其目标读者是那些寻求解析数百万甚至数十亿数量级域名的人。无需特殊配置，MassDNS就能使用公开可用的解析器每秒解析超过350,000个名称。
工具编译
将git仓库克隆cd到项目根文件夹中。然后运行make从源代码构建。
工具用法
Usage: ./bin/massdns [options] [domainlist]
-b –bindto Bind to IP address and port. (Default: 0.0.0.0:0)
–busy-poll Use busy-wait polling instead of epoll.
-c –resolve-count Number of resolves for a name before giving up. (Default: 50)
–drop-group Group to drop privileges to when running as root. (Default: nogroup)
–drop-user User to drop privileges to when running as root. (Default: nobody)
–flush Flush the output file whenever a response was received.
-h –help Show this help.
-i –interval Interval in milliseconds to wait between multiple resolves of the same
domain. (Default: 500) -l
–error-log Error log file path. (Default: /dev/stderr)
–norecurse Use non-recursive queries. Useful for DNS cache snooping.
-o –output Flags for output formatting.
–predictable Use resolvers incrementally. Useful for resolver tests.
–processes Number of processes to be used for resolving. (Default: 1)
-q –quiet Quiet mode.
–rcvbuf Size of the receive buffer in bytes.
–retry Unacceptable DNS response codes. (Default: REFUSED)
-r –resolvers Text file containing DNS resolvers.
–root Do not drop privileges when running as root. Not recommended.
-s –hashmap-size Number of concurrent lookups. (Default: 10000)
–sndbuf Size of the send buffer in bytes.
–sticky Do not switch the resolver when retrying.
–socket-count Socket count per process. (Default: 1)
-t –type Record type to be resolved. (Default: A)
–verify-ip Verify IP addresses of incoming replies.
-w –outfile Write to the specified output file instead of standard output.
Output flags:
S – simple text output
F – full text output
B – binary output
J – ndjson output
使用示例
解析目标域名（位于lists的resolvers.txt中）的AAAA记录，转化结果存储至result.txt中：
$ ./bin/massdns -r lists/resolvers.txt -t AAAA domains.txt > results.txt
或者运行下列命令：
$ ./bin/massdns -r lists/resolvers.txt -t AAAA -w results.txt domains.txt
样本输出
默认配置下，MassDNS将输出响应数据包，格式为文本格式，输出样例如下：
;; Server: 77.41.229.2:53
;; Size: 93
;; Unix time: 1513458347
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 51298
;; flags: qr rd ra ; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 0
;; QUESTION SECTION:
example.com. IN A
;; ANSWER SECTION:
example.com. 45929 IN A 93.184.216.34
;; AUTHORITY SECTION:
example.com. 24852 IN NS b.iana-servers.net.
example.com. 24852 IN NS a.iana-servers.net.
输出结果包含了解析的IP地址，可以帮助我们轻松对输出结果进行过滤。
数据解析
代码库中包含了一个名为resolvers.txt的文件，其中包含了一套有子项目提供的已过滤的解析器子集。请注意，MassDNS的使用可能会提升系统/网络负载，因为需要加载大量解析器，具体将决定你的ISP。
MassDNS的DNS解析实现目前还不完整，只支持最常见的一些记录类型。欢迎您通过代码贡献来帮助改变这种状况。
PTR记录
MassDNS包含了一个Python脚本，允许我们解析所有的IPv4 PTR记录：
$ ./scripts/ptr.py | ./bin/massdns -r lists/resolvers.txt -t PTR -w ptr.txt
请注意，in-addr.arpa中的标签会被反转。为了解析域名为1.2.3.4的地址，MassDNS将需要以“ 4.3.2.1.in-addr.arpa”的方式来作为输入查询名称。此时，Python脚本并不会按升序解析记录，这样可以避免在IP v4子网的域名服务器上突然出现的负载激增。
网络侦察＆爆破子域名
注意：请不要随意使用该工具，适当调整-s参数预设给权威域名服务器造成负载压力。
跟subbrute类似，MassDNS允许我们使用subbrute.py脚本来对子域名进行爆破枚举举：
$ ./scripts/subbrute.py lists/names.txt example.com | ./bin/massdns -r lists/resolvers.txt -t A -o S -w results.txt
作为一种额外的网络侦察手段，ct.py脚本可以从crt.sh中抓取数据，并从证书透明日志中提取子域名：
$ ./scripts/ct.py example.com | ./bin/massdns -r lists/resolvers.txt -t A -o S -w results.txt
文章来源：
https://github.com/blechschmidt/massdns0daybank
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