我正在EC2中运行一个DNS服务器,昨天当我检查我的计费仪表板并且本月发现1.86 TB的已用数据时它正在推动大约20mbps.这对我的小型项目实验室来说是个大账单.我从来没有注意到性能下降,也没有费心去设置流量阈值,但我现在已经花费了200美元的带宽费用.
似乎有人使用我的DNS服务器作为放大攻击的一部分,但是我不知道如何.
配置在下面.
// BBB.BBB.BBB.BBB = ns2.mydomain.com ip address options { listen-on port 53 { any; }; // listen-on-v6 port 53 { ::1; }; directory "/var/named"; dump-file "/var/named/data/cache_dump.db"; statistics-file "/var/named/data/named_stats.txt"; memstatistics-file "/var/named/data/named_mem_stats.txt"; allow-transfer { BBB.BBB.BBB.BBB; }; allow-query-cache { BBB.BBB.BBB.BBB; }; allow-query { any; }; allow-recursion { none; }; empty-zones-enable no; forwarders { 8.8.8.8; 8.8.4.4; }; fetch-glue no; recursion no; dnssec-enable yes; dnssec-validation yes; /* Path to ISC DLV key */ bindkeys-file "/etc/named.iscdlv.key"; managed-keys-directory "/var/named/dynamic"; }; logging { channel default_debug { file "data/named.run"; severity dynamic; }; }; zone "." IN { type hint; file "named.ca"; }; zone "mydomain.com" IN { type master; file "zones/mydomain.com"; allow-transfer { BBB.BBB.BBB.BBB; localhost; }; };
鉴于这种配置,我不应该回答任何关于区域的查询我不在本地托管吗?这个服务器是几个域的SOA,但不用于查看我的其他服务器(每个人都针对OpenDNS或Google).我在这里有什么指示错误,还是我忘了?我的日志(63MB)充满了这个:
client 58.215.173.155#4444: query (cache) 'cpsc.gov/ANY/IN' denied client 58.215.173.155#4444: query (cache) 'cpsc.gov/ANY/IN' denied client 58.215.173.155#4444: query (cache) 'cpsc.gov/ANY/IN' denied client 58.215.173.155#4444: query (cache) 'cpsc.gov/ANY/IN' denied client 58.215.173.155#4444: query (cache) 'cpsc.gov/ANY/IN' denied client 58.215.173.155#4444: query (cache) 'cpsc.gov/ANY/IN' denied client 218.93.206.228#4444: query (cache) 'cpsc.gov/ANY/IN' denied client 218.93.206.228#4444: query (cache) 'cpsc.gov/ANY/IN' denied client 218.93.206.228#4444: query (cache) 'cpsc.gov/ANY/IN' denied client 218.93.206.228#4444: query (cache) 'cpsc.gov/ANY/IN' denied client 218.93.206.228#4444: query (cache) 'cpsc.gov/ANY/IN' denied client 218.93.206.228#4444: query (cache) 'cpsc.gov/ANY/IN' denied client 50.19.220.154#4444: query (cache) 'cpsc.gov/ANY/IN' denied client 50.19.220.154#4444: query (cache) 'cpsc.gov/ANY/IN' denied client 50.19.220.154#4444: query (cache) 'cpsc.gov/ANY/IN' denied client 50.19.220.154#4444: query (cache) 'cpsc.gov/ANY/IN' denied client 50.19.220.154#4444: query (cache) 'cpsc.gov/ANY/IN' denied client 50.19.220.154#4444: query (cache) 'cpsc.gov/ANY/IN' denied client 123.207.161.124#4444: query (cache) 'cpsc.gov/ANY/IN' denied client 123.207.161.124#4444: query (cache) 'cpsc.gov/ANY/IN' denied client 123.207.161.124#4444: query (cache) 'cpsc.gov/ANY/IN' denied client 123.207.161.124#4444: query (cache) 'cpsc.gov/ANY/IN' denied client 123.207.161.124#4444: query (cache) 'cpsc.gov/ANY/IN' denied
解决方法
即使您的服务器设置为仅响应您的权威查询,它仍然可能用于放大攻击 – 任何针对区域根的查询都可能触发相当大的UDP响应,因为区域根目录倾向于有许多记录,特别是SPF / DKIM / DNSSEC.
这可能是您系统上发生的事情 – 使用tcpdump进行确认.如果他们在放大攻击中使用您的权威记录,那么您最好的选择就是简单地转移到新的IP并希望他们不遵循,更改您的区域根记录以使其成为效率较低的放大载体,或实施响应率限制(如果您的BIND支持它).
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