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Ubuntu 16.04LTS 的 DNS 问题

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Ubuntu 16.04LTS 的 DNS 问题

我面临的问题如下：

我已经配置了一个虚拟机 Ubuntu，但该机器无法使用我的内部 DNS 服务器解析 DNS 记录。“DNS 服务器是 windows_server_2008_R2 AD/DNS 组合”

拓扑： 拓扑

Ubuntu 配置：

root@rboshmaf-ubuntu:~# cat /etc/network/interfaces

interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet static
          address 192.168.1.12
          netmask 255.255.255.0
          dns-nameservers 172.16.1.11 144.254.71.184
          gateway 192.168.1.1



root@rboshmaf-ubuntu:~# route

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         192.168.1.1     0.0.0.0         UG    0      0        0 eth0
link-local      *               255.255.0.0     U     1000   0        0 eth0
192.168.1.0     *               255.255.255.0   U     0      0        0 eth0



root@rboshmaf-ubuntu:~# cat /etc/resolv.conf

Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 172.16.1.11
nameserver 144.254.71.184

与Ubuntu处于同一网络“使用同一个DNS服务器”的vm wimdows_7机器能够得到结果。

ASA 配置“流量从高安全性 > 低安全性，需要进行检查”

在 ASA 上捕获了信息以查看发生了什么，我发现奇怪的是，在 Ubuntu“不工作的情况下”，查询将转到 1.1.168.192.in-addr.arpa ubuntu_cap
在 Windows“工作情况”下，查询将转到 1.1.16.172.in-addr.arpa windows_cap

请记住，Windows 服务器 IP 是 172.16.1.11，DNS 记录都在那里dns_config_windows

从 windows_7 ping\nslookup

C:\Users\administrator>ping 172.16.1.11
Pinging 172.16.1.11 with 32 bytes of data:
Reply from 172.16.1.11: bytes=32 time=1ms TTL=128

Ping statistics for 172.16.1.11:
    Packets: Sent = 1, Received = 1, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 1ms, Maximum = 1ms, Average = 1ms
Control-C
^C

C:\Users\administrator>nslookup rboshmaf-ubuntu 172.16.1.11

Server:  win-o33saf37ksq.raedlab.local

Address:  172.16.1.11

Name:    rboshmaf-ubuntu.raedlab.local

Address:  192.168.1.12

从 Ubuntu ping\nslookup

root@rboshmaf-ubuntu:~# ping 172.16.1.11
PING 172.16.1.11 (172.16.1.11) 56(84) bytes of data.
64 bytes from 172.16.1.11: icmp_seq=1 ttl=128 time=1.25 ms
^C
--- 172.16.1.11 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 1.258/1.258/1.258/0.000 ms

root@rboshmaf-ubuntu:~# nslookup rboshmaf-ubuntu 172.16.1.11
Server:         172.16.1.11
Address:        172.16.1.11#53

** server can't find rboshmaf-ubuntu: SERVFAIL

我不喜欢捕获的内容是，Ubuntu 查询将转到 1.1.168.192.in-addr.arpa，而这不是 DNS 服务器，实际上 192.168.1.1 是 Ubuntu 的网关，位于“ASA 的内部接口”

对于该情况有任何想法或建议吗？

谢谢！

编辑#1

为了从图片中删除 ASA，我重新配置了拓扑，如下所示：

新拓扑

新的 Ubuntu 配置：

   root@rboshmaf-ubuntu:~# cat /etc/network/interfaces 
     # interfaces(5) file used by ifup(8) and ifdown(8)
     auto lo
     iface lo inet loopback
     auto eth0
     iface eth0 inet static
           address 172.16.1.12
           netmask 255.255.255.0
           dns-nameservers 172.16.1.11 144.254.71.184
           gateway 172.16.1.1

   root@rboshmaf-ubuntu:~# ifconfig
   eth0      Link encap:Ethernet  HWaddr 00:50:56:99:3c:b3  
             inet addr:172.16.1.12  Bcast:172.16.1.255  Mask:255.255.255.0
             UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
             RX packets:20756 errors:0 dropped:0 overruns:0 frame:0
             TX packets:6959 errors:0 dropped:0 overruns:0 carrier:0
             collisions:0 txqueuelen:1000 
             RX bytes:29614255 (29.6 MB)  TX bytes:480744 (480.7 KB)

   root@rboshmaf-ubuntu:~# cat /etc/resolv.conf 
   # Dynamic resolv.conf(5) file for glibc resolver(3) generated by 
   resolvconf(8)
   #     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
   nameserver 172.16.1.11
   nameserver 144.254.71.184

   root@rboshmaf-ubuntu:~# route
   Kernel IP routing table
   Destination     Gateway         Genmask         Flags Metric Ref    Use 
   Iface
   default         172.16.1.1      0.0.0.0         UG    0      0        0 
   eth0
   link-local      *               255.255.0.0     U     1000   0        0 
   eth0
   172.16.1.0      *               255.255.255.0   U     0      0        0 
   eth0

从 Ubuntu 执行 ping/nslookup

root@rboshmaf-ubuntu:~# ping 172.16.1.11
PING 172.16.1.11 (172.16.1.11) 56(84) bytes of data.
64 bytes from 172.16.1.11: icmp_seq=1 ttl=128 time=1.23 ms
64 bytes from 172.16.1.11: icmp_seq=2 ttl=128 time=0.811 ms
64 bytes from 172.16.1.11: icmp_seq=3 ttl=128 time=0.981 ms
^C
--- 172.16.1.11 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2001ms
rtt min/avg/max/mdev = 0.811/1.007/1.231/0.176 ms
root@rboshmaf-ubuntu:~# nslookup rboshmaf-ubuntu 172.16.1.11
Server:     172.16.1.11
Address:    172.16.1.11#53

** server can't find rboshmaf-ubuntu: SERVFAIL

捕获 ASA 确认没有流量到达 ASA

rboshmaf-asa# capture cap1 interface dmz match ip h 172.16.1.12 h 172.16.1.11
rboshmaf-asa# show capture
capture cap1 type raw-data interface dmz [Capturing - 0 bytes]
  match ip host 172.16.1.12 host 172.16.1.11

我在 ubuntu 上使用 tcpdump

root@rboshmaf-ubuntu:~# tcpdump -n -i eth0 | grep 172.16.1.11.53
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
10:17:07.417553 IP 172.16.1.12.54685 > 172.16.1.11.53: 43282+ A? rboshmaf-ubuntu. (33)
10:17:07.418939 IP 172.16.1.11.53 > 172.16.1.12.54685: 43282 ServFail 0/0/0 (33)
10:17:27.270067 IP 172.16.1.12.56675 > 172.16.1.11.53: 50648+ A? ntp.ubuntu.com. (32)
10:17:27.270803 IP 172.16.1.11.53 > 172.16.1.12.56675: 50648 3/0/0 A 91.189.89.198, A 91.189.89.199, A 91.189.91.157 (80)

从 windows_server 本地捕获新捕获

谢谢！

答案1

我的猜测是：

  1. DNS 服务器不接受端口 53 上的请求。请尝试使用telnet端口53来测试。
  2. 如果流程正常，请检查您的/etc/hostsUbuntu，可能有一个可能产生冲突的本地记录。
  3. 如果以上方法没有给你答案，那么可能是 DNS 服务器的配置有问题。确保你已配置 A 记录以及用于授权的 NS 记录。

答案2

问题是机器不知道在哪个 FQDN 中搜索，我编辑了 /etc/network/interfaces 以包含“dns-search raedlab.local”

rboshmaf@rboshmaf-ubuntu:~$ cat /etc/network/interfaces
# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet static
      address 192.168.1.12
      netmask 255.255.255.0
      dns-nameservers 172.16.1.11 144.254.71.184
      gateway 192.168.1.1
      dns-search raedlab.local < this was missing in my configuration

rboshmaf@rboshmaf-ubuntu:~$ nslookup rboshmaf-ubuntu 172.16.1.11
Server:     172.16.1.11
Address:    172.16.1.11#53

Name:   rboshmaf-ubuntu.raedlab.local
Address: 192.168.1.12

你也可以查看 askubuntu 上的这篇文章，了解有关 dns-search 功能的信息/etc/network/interfaces 中的 dns-search 选项含义是什么？

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