☰

MDNS 多播 DNS 和 resolv.conf 文件

tag-icon • tag-icon linux networking dns dmesg mdns
MDNS 多播 DNS 和 resolv.conf 文件

MDNS（多播 dns）问题是否会导致 resolv.conf 文件中出现重复行？

例如，我们有以下 resolv.conf 文件

more /etc/resolv.conf
search coronplesdf.hh.com
server 108.16.1.71
domain coronplesdf.hh.com
domain coronplesdf.hh.com
domain coronplesdf.hh.com
domain coronplesdf.hh.com
domain coronplesdf.hh.com
domain coronplesdf.hh.com
domain coronplesdf.hh.com
domain coronplesdf.hh.com
domain coronplesdf.hh.com
domain coronplesdf.hh.com

例如我们从 dmesg 得到的信息

[6484420.812643] raid6: using avx2x2 recovery algorithm
[6484420.859086] Btrfs loaded
[6484426.278636] nr_pdflush_threads exported in /proc is scheduled for removal
[6484708.776239] ixgbe 0000:04:00.0: invalid short VPD tag 06 at offset 4
[6900952.098901] perf: interrupt took too long (6247 > 6167), lowering kernel.perf_event_max_sample_rate to 32000
[7372848.819396] Peer 0000:0000:0000:0000:0000:ffff:0a15:f030:1054/8042 unexpectedly shrunk window 3002395993:3002395997 (repaired)
[8139485.039423] Turbo disabled by BIOS or unavailable on processor
[8380300.891343] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380320.890541] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380440.896206] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380460.895001] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380463.207397] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380467.316531] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380468.363352] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380469.332044] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380489.330943] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380509.329849] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380529.328678] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380549.468256] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380569.326474] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380589.340946] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380609.339969] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380619.870472] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380620.964216] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380621.979847] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380641.869255] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380661.883737] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69

答案1

第 2 层网络性能优化/怪癖不应影响resolv.conf.我敢打赌，您的某些 devops 脚本上的一些非幂等操作会在多次调用中添加/添加域行。

此外，mDNS 不使用中心点，并且独立于常规 DNS；进行通信的设备向整个网络宣布它们的名称/IP 地址（m 代表多播）。由于我拥有 DNS 中的所有内容，因此我通常会停止“我的”企业服务器中的 mDNS 守护进程/avahi。

答案2

不，错误的 MDNS 数据包校验和不应导致多domain行输入，/etc/resolv.conf反之亦然。

消息

UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69

将表明 IP 为 82.2.33.1 的系统正在接收来自 73.2.33.11 的错误 UDP 数据包，因此 IP 为 73.2.33.11 的系统可能存在软件错误或某些 NIC 硬件故障。它还可能试图通过故意发送不良数据包并查看您的系统如何/是否响应它们来探测您的系统。

我假设您出于隐私原因修改了 IP 地址，因为在同一网段中使用 73.xxx 和 82.xxx 这样的 IP 通常没有意义。 MDNS 通常仅在单个网段内有用，因此，如果 73.2.33.11 不是本地网络的一部分，您可能希望在路由器（或专用防火墙设备、如果你有一个）。

相关内容