域名系统 – BIND – 升级到CentOS 6.7后,传出的NS查询增加了吗？

在几个缓存名称服务器中将BIND升级到9.8.2rc1-RedHat-9.8.2-0.37.rc1.el6_7.2后,我注意到它正在进行大量传出的NS查询,而不会更改传入的流量或模式.
结果,服务器消耗了更多的CPU和网络带宽,从而导致了性能和容量问题.

以前安装的版本9.8.2rc1-RedHat-9.8.2-0.30.rc1.el6_6.1或9.8.2-0.30.rc1.el6_6.3(CentOS 6.6上的最新版本)没有发生这种情况,我可以查看与升级时间匹配的图表中的更改.

图表如下,棕色带对应于NS查询.中断是由于升级BIND后服务器重新启动.

传入的查询：

传出查询：

tcpdump显示数千个查询/秒,要求为每个查询的主机名提供NS记录.这很奇怪,因为我期望看到域(example.com)的NS查询而不是主机(www.example.com).

16:19:42.299996 IP xxx.xxx.xxx.xxx.xxxxx > 198.143.63.105.53:  45429% [1au] NS? e2svi.x.incapdns.net. (49)
16:19:42.341638 IP xxx.xxx.xxx.xxx.xxxxx > 198.143.61.5.53:    53265% [1au] NS? e2svi.x.incapdns.net. (49)
16:19:42.348086 IP xxx.xxx.xxx.xxx.xxxxx > 173.245.59.125.53:  38336% [1au] NS? www.e-monsite.com. (46)
16:19:42.348503 IP xxx.xxx.xxx.xxx.xxxxx > 205.251.195.166.53: 25752% [1au] NS? moneytapp-api-us-1554073412.us-east-1.elb.amazonaws.com. (84)
16:19:42.367043 IP xxx.xxx.xxx.xxx.xxxxx > 205.251.194.120.53: 24002% [1au] NS? LB-lomadee-adservernew-678401945.sa-east-1.elb.amazonaws.com. (89)
16:19:42.386563 IP xxx.xxx.xxx.xxx.xxxxx > 205.251.194.227.53: 40756% [1au] NS? ttd-euwest-match-adsrvr-org-139334178.eu-west-1.elb.amazonaws.com. (94)

客户端请求的tcpdump显示：

## client query
17:30:05.862522 IP <client> > <my_server>.53: 1616+ A? cid-29e117ccda70ff3b.users.storage.live.com. (61)

    ## recursive resolution (OK)
    17:30:05.866190 IP <my_server> > 134.170.107.24.53: 64819% [1au] A? cid-29e117ccda70ff3b.users.storage.live.com. (72)
    17:30:05.975450 IP 134.170.107.24.53 > <my_server>: 64819*- 1/0/1 A 134.170.111.24 (88)

    ## garbage NS queries
    17:30:05.984892 IP <my_server> > 134.170.107.96.53: 7145% [1au] NS? cid-29e117ccda70ff3b.users.storage.live.com. (72)
    17:30:06.105388 IP 134.170.107.96.53 > <my_server>: 7145- 0/1/1 (158)

    17:30:06.105727 IP <my_server> > 134.170.107.72.53: 36798% [1au] NS? cid-29e117ccda70ff3b.users.storage.live.com. (72)
    17:30:06.215747 IP 134.170.107.72.53 > <my_server>: 36798- 0/1/1 (158)

    17:30:06.218575 IP <my_server> > 134.170.107.48.53: 55216% [1au] NS? cid-29e117ccda70ff3b.users.storage.live.com. (72)
    17:30:06.323909 IP 134.170.107.48.53 > <my_server>: 55216- 0/1/1 (158)

    17:30:06.324969 IP <my_server> > 134.170.107.24.53: 53057% [1au] NS? cid-29e117ccda70ff3b.users.storage.live.com. (72)
    17:30:06.436166 IP 134.170.107.24.53 > <my_server>: 53057- 0/1/1 (158)

## response to client (OK)
17:30:06.438420 IP <my_server>.53 > <client>: 1616 1/1/4 A 134.170.111.24 (188)

我认为这可能是一个缓存填充问题,但即使在服务器运行一周后它也没有消退.

一些细节：

>问题没有发生在CentOS 6.6 x86_64完全修补
>服务器正在运行CentOS 6.7 x86_64(完全修补,截至2015-08-13).
> BIND在chroot的环境中运行,带有额外的参数ROOTDIR = / var / named / chroot; OPTIONS =“ – 4 -n4 -S 8096”
>编辑下面的named.conf内容

这里发生了什么？有没有办法更改配置以避免此行为？

acl xfer {
(snip)
};

acl bogusnets {
0.0.0.0/8; 1.0.0.0/8; 2.0.0.0/8; 192.0.2.0/24; 224.0.0.0/3;
};

acl clients {
(snip)
};

acl privatenets {
127.0.0.0/24; 10.0.0.0/8; 172.16.0.0/12; 192.168.0.0/16;
};

acl ops {
(snip)
};

acl monitoring {
(snip)
};

include "/etc/named.root.key";
key rndckey {
        algorithm       hmac-md5;
        secret          (snip);
};

key "monitor" {
        algorithm hmac-md5;
        secret (snip);
};

controls { inet 127.0.0.1 allow { localhost; } keys { rndckey; };
           inet (snip) allow { monitoring; } keys { monitor; }; };

logging {
        channel default_syslog { syslog local6; };
        category lame-servers { null; };
        channel update_debug {
                 file "/var/log/named-update-debug.log";
                 severity  debug 3;
                 print-category yes;
                 print-severity yes;
                 print-time     yes;
        };
        channel security_info    {
                 file "/var/log/named-auth.info";
                 severity  info;
                 print-category yes;
                 print-severity yes;
                 print-time     yes;
        };
        channel querylog{
                file "/var/log/named-querylog" versions 3 size 10m;
                severity info;
                print-category yes;
                print-time     yes;
        };

        category queries { querylog; };
        category update { update_debug; };
        category security { security_info; };
        category query-errors { security_info; };
};

options {
        directory "/var/named";
        pid-file "/var/run/named/named.pid";
        statistics-file "/var/named/named.stats";
        dump-file "/var/named/named_dump.db";
        zone-statistics yes;
        version "Not disclosed";

        listen-on-v6 { any; };
        allow-query { clients; privatenets; };
        recursion yes;                             // default
        allow-recursion { clients; privatenets; };
        allow-query-cache { clients; privatenets; };
        recursive-clients 10000;
        resolver-query-timeout 5;
        dnssec-validation no;
        querylog no;

        allow-transfer { xfer; };
        transfer-format many-answers;
        max-transfer-time-in 10;
        notify yes;                                // default

        blackhole { bogusnets; };

        response-policy {
                zone "rpz";
                zone "netrpz";
        };
};

include "/etc/named.rfc1912.zones";
include "/etc/named.zones";

statistics-channels { inet (snip) port 8053 allow { ops; }; inet 127.0.0.1 port 8053 allow { 127.0.0.1; }; };

zone "rpz" { type slave; file "slaves/rpz"; masters { (snip) }; };
zone "netrpz" { type slave; file "slaves/netrpz"; masters { (snip) }; };

行为的变化似乎与此更改日志有关(来自RedHat的网站)：

2015-02-19 12:00:00
Tomas Hozza <thozza@redhat.com> 32:9.8.2-0.35.rc1:
- Enable RPZ-NSIP and RPZ-NSDNAME during compilation (#1176476)

NSDNAME启用基于权威名称服务器的过滤策略,可以编写例如：

a.ns.facebook.com.rpz-nsdname CNAME .

阻止任何将a.ns.facebook.com作为权威服务器的记录的响应.

我们在RPZ区域文件的顶部有一个迷路条目：

ns.none.somewhere.rpz-nsdname   CNAME   .

删除此条目会使行为停止.

不幸的是,添加任何NSDNAME指令将再次触发相同的行为.

根据this article,在BIND 9.10中,优化了RPZ功能的CPU消耗.只有RHEL7才能提供此补丁.

域名系统 – BIND – 升级到CentOS 6.7后,传出的NS查询增加了吗？

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