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最终目标

tag-icon • tag-icon dig nslookup
最终目标

我的研究表明，nslookup从来没有真正打算用于脚本化使用：dig而是使用它，它带有+short选项，根据查询参数生成机器可读的输出。

dig +short myip.opendns.com @resolver1.opendns.com

话虽这么说，我的路由器不支持 dig 并支持nslookup.我试图将返回的 IP 地址保存为一个变量，以便与实际 IP 地址进行比较：

ip=$(curl --沉默http://api.ipify.org/）

awk在Ubuntu上成功：

nslookup yahoo.com  | awk -F': ' 'NR==6 { print $2 } '

但在 DD-WRT 路由器上返回错误：

nslookup: can't resolve '(null)'
2001:4998:58:1836::10 media-router-fp1.prod1.media.vip.bf1.yahoo.com

最终目标

我有 CLI.sh命令更新 DDNS 服务：每当测量和存储的 DDNS IP 地址不同时，我想执行更新命令（CRON 作业每 5 分钟检查一次）。

问题

相当于上面所说的 dig 示例的最简单的 nslookup 是什么？

观察、反馈和测试区域

添加了第二个参数：

root@DD-WRT:/opt# nslookup mydomain.asuscomm.com  resolver1.opendns.com
Server:    208.67.222.222
Address 1: 208.67.222.222 resolver1.opendns.com

Name:      mydomain.asuscomm.com
Address 1: 7W.10X.7Y.6Z c-7W-10X-7Y-6Z.hsd1.fl.comcast.net

devnull: > /dev/null

root@DD-WRT:/opt# nslookup mydomain.asuscomm.com  > /dev/null
nslookup: can't resolve '(null)'

devnull: > /dev/null 2>&1

root@DD-WRT:/opt# nslookup mydomain.asuscomm.com  > /dev/null 2>&1
root@DD-WRT:/opt#

键入 nslookup：

root@DD-WRT:~# type nslookup
nslookup is /usr/bin/nslookup

管道到 grep 然后到文件：

root@DD-WRT:/opt# nslookup myDomain.asuscomm.com | grep Address > test.txt
nslookup: can't resolve '(null)'
root@DD-WRT:/opt# cat test.txt
Address 1: 7W.10X.7Y.6Z c-7W-10X-7Y-6Z.hsd1.fl.comcast.net

查找

root@DD-WRT:/opt/test# nslookup myFQDN.asuscomm.com

Name:      mydomain.asuscomm.com
Address 1: 7x.10x.7.x6x c-7x-10x-7x-6x.hsd1.fl.comcast.net

nslookup 雅虎

root@DD-WRT:/opt# nslookup yahoo.com

nslookup: can't resolve '(null)'

Name:      yahoo.com
Address 1: 2001:4998:c:1023::5 media-router-fp2.prod1.media.vip.gq1.yahoo.com
Address 2: 2001:4998:58:1836::10 media-router-fp1.prod1.media.vip.bf1.yahoo.com
Address 3: 2001:4998:58:1836::11 media-router-fp2.prod1.media.vip.bf1.yahoo.com
Address 4: 2001:4998:c:1023::4 media-router-fp1.prod1.media.vip.gq1.yahoo.com
Address 5: 2001:4998:44:41d::3 media-router-fp1.prod1.media.vip.ne1.yahoo.com
Address 6: 2001:4998:44:41d::4 media-router-fp2.prod1.media.vip.ne1.yahoo.com
Address 7: 72.30.35.9 media-router-fp1.prod1.media.vip.bf1.yahoo.com
Address 8: 98.137.246.7 media-router-fp1.prod1.media.vip.gq1.yahoo.com
Address 9: 98.138.219.231 media-router-fp1.prod1.media.vip.ne1.yahoo.com
Address 10: 98.138.219.232 media-router-fp2.prod1.media.vip.ne1.yahoo.com
Address 11: 72.30.35.10 media-router-fp2.prod1.media.vip.bf1.yahoo.com
Address 12: 98.137.246.8 media-router-fp2.prod1.media.vip.gq1.yahoo.com

格列普：

root@DD-WRT:/# nslookup yahoo.com | grep gq1


nslookup: can't resolve '(null)'
Address 1: 2001:4998:c:1023::4 media-router-fp1.prod1.media.vip.gq1.yahoo.com
Address 6: 2001:4998:c:1023::5 media-router-fp2.prod1.media.vip.gq1.yahoo.com
Address 7: 98.137.246.8 media-router-fp2.prod1.media.vip.gq1.yahoo.com
Address 8: 98.137.246.7 media-router-fp1.prod1.media.vip.gq1.yahoo.com

格列普：

root@DD-WRT:/opt# nslookup yahoo.com | grep -o -E '([0-9][0-9]?[0-9]?\.?){4}$'

nslookup: can't resolve '(null)'

grep3:

root@DD-WRT:/opt# nslookup mydomain.asuscomm.com | grep -o -E '([0-9][^:][0-9]?[0-9]?\.?){4}' > output.txt
nslookup: can't resolve '(null)'
root@DD-WRT:/opt# cat output.txt
7W.10X.7Y.6Z
W-10X-7Y-6Z.

答案1

这有效：

nslookup "$D" 2>/dev/null  | grep "Address " | sed 's/.*: //g;s/ .*//g'

但请注意

  • 它可以返回多个地址，因此循环遍历它们
  • 如果你不需要它们，则 grep 出 ipv6
  • 许多域名每次查询都会解析不同的内容（例如亚马逊随机使用cloudfront、fastly或其他ip）

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