Nameserver SOA Check

[Celay]

Hello Host-Monitor community,

I want to write a script to check the SOA records from different Nameservers for differences, does anyone have an example script or an script that does that already?
I have nearly to no experience in Powershell so I don't really know how to make a script all by myself and sadly couldn't find any good examples either.

Greetings
Celay

[KS-Soft]

If you are using PowerShell version 3 or 4, you may use Resolve-DnsName command
>resolve-dnsname www.microsoft.com -type soa

https://technet.microsoft.com/en-us/lib ... 90781.aspx

Regards
Alex

[KS-Soft Europe]

Windows nslookup utility also can be used with script.
example of JavaScript that uses nslookup tool and checks SOA record for modification (for HostMonitor Shell Script test method):

Code: Select all

statusUnknown     = "scriptRes:Unknown:";
statusOk          = "scriptRes:Ok:";
statusBad         = "scriptRes:Bad:";

objArgs = WScript.Arguments;

if (objArgs.length != 3) {
  WScript.StdOut.Write(statusUnknown + "Required 3 parameters: <host name> <DNS server> <tempfilePath>");
  WScript.Quit;
}

var host = objArgs(0);
var DNS = objArgs(1);
var fname = objArgs(2);

var WshShell = new ActiveXObject("WScript.Shell");
var Str = WshShell.Exec("nslookup -querytype=soa "+host+" "+DNS).StdOut.ReadAll();
var StrB = getFile(fname);

if (Str == StrB) {
  WScript.StdOut.Write(statusOk);
} else {
  writeFile(fname,Str)
  WScript.StdOut.Write(statusBad+"SOA modified");
}

function writeFile(fname,data) {
  var fso = new ActiveXObject("Scripting.FileSystemObject"),
  thefile=fso.CreateTextFile(fname,true);
  thefile.Write(data);
  thefile.Close();
}

function getFile(fname) {
try {
  var oFS = new ActiveXObject('Scripting.FileSystemObject');

  if (oFS.FileExists(fname)) {
  var oFile = oFS.OpenTextFile(fname);
  var str = ''
  while (!oFile.AtEndOfStream) {
  str = oFile.ReadAll();
  }
  oFile.Close();
  return str;
  }

} catch(e) {
  WScript.StdOut.Write(statusUnknown + e.message+' ['+fname.replace(/\\\\/g,'\\')+']');
  WScript.Quit;
  return e.message;
}
}

Start cmd: cmd /c cscript /B /E:JScript %Script% %Params%
Script requires 3 parameters: <host name> <DNS server> <tempfilePath>
E.g.:
google.com 8.8.8.8 D:\dnssoa_temp1.txt

Please note, separate temp file should be used for each test item.

[Celay]

First of all thanks for the fast response, great support as always.

The problem I have is not getting the SOA record of one Nameserver but of more than one and then checking them for differences.

I thought about saving the SOA record of one Nameserver in an temp .txt but I believe there could also be an way to save them as an variable and then check the variables for differences. But as I said, I don't really have any experience in Powershell/VBScript so I am not sure if it is even possible to save an variable in an Powershell script.

[KS-Soft Europe]

You will not be able to store data in powershell/JS/VB varible, because, each time test starts script, new script instance is running.
You may save data into file and compare records from different DNS servers with records from file.
If you'll provide more information we may help you with the script:
1. What records should be compared? Example using nslookup tool?
2. What should be done, when some DNS server returns different record?
e.g.:
set Bad Status, overwrite temp file with updated info
or
set Bad Status, do not overwrite temp file (file will be overwritten manually)
3. May we see some examples of different SOA records using nslookup tool?

[Celay]

Again thanks for the fast response and offer to help me.
To answer your questions:

1.The SOA records of all the Nameservers assigned to one site. example: google.com ns1.google.com - ns4.google.com
(nslookup -type=ns google.com) +
(nslookup -type=soa google.com NS1.google.com)

2.When a Server returns a different record it should simply set Bad Status in Host-Monitor.

3.I certainly (luckily) don't have any Site with different SOA records currently, but heres an example with Google. The NS1.google.com has the SOA 2014112500 currently, so do all other NS*.google.com Nameservers, the Script should first check site and get all nameservers
(nslookup -type=ns google.com) then get the SOA of all the nameservers (nslookup -type=soa google.com NS1.google.com,...) and then check them for differences if they're all the same = Good Status, otherwise = Bad Status.

[KS-Soft Europe]

Would it be enough to compare only SOA serial numbers from different DNS servers?

[Celay]

Would it be enough to compare only SOA serial numbers from different DNS servers?

It needs to check the Nameservers assigned to the Website, only SOA nothing more.

[KS-Soft Europe]

SOA record consist of several fields:

• Serial number
  Refresh rate
  Update Retry
  Expiry
  TTL

My question: do you need to check/compare only "Serial number" or other fields should also be checked/compared?

[Celay]

Ah that's what you meant, yes it only needs to check the serial.

Again thanks for your help, I am going to sleep now will be back tomorrow around 10am.

[KS-Soft Europe]

JS script for Shell Script test method.
Script checks assigned DNS servers for the domain, then compares "serial" field of all DNS servers for specified domain.
Reply shows SOA serial and DNS count.

Code: Select all

statusUnknown     = "scriptRes:Unknown:";
statusOk          = "scriptRes:Ok:";
statusBad         = "scriptRes:Bad:";

objArgs = WScript.Arguments;

if (objArgs.length < 1||objArgs.length > 2) {
  WScript.StdOut.Write(statusUnknown + "Required 1 or 2 parameters: <host name> [<DNS>]");
  WScript.Quit;
}

var host = objArgs(0);
var DNS = "";
if (objArgs.length>1) DNS = objArgs(1);

var WshShell = new ActiveXObject("WScript.Shell");

DNSs = getDNSs(host,DNS);

if (DNSs.length==0) {
  WScript.StdOut.Write(statusUnknown+"Cannot get DNS servers for "+host+". Try to specify any DNS as 2nd parameter for the test.");
  WScript.Quit;
  }

var SOA = getSOAserial(host,DNSs[0]);
var SOA2 = "";

for (i = 1; i < DNSs.length; i++)
{
  SOA2 =  getSOAserial(host,DNSs[i]);
  if (SOA!=SOA2) {
    WScript.StdOut.Write(statusBad+SOA2+" "+DNSs[i]);
    WScript.Quit;
    }
}
  WScript.StdOut.Write(statusOk+SOA+" ("+DNSs.length+")");

function getSOAserial(host,DNS) {
var Str = WshShell.Exec("nslookup -querytype=soa "+host+" "+DNS).StdOut.ReadAll();

var pos = Str.indexOf("serial  =");
if (pos==-1) return "<serial not found>";

Str = Str.substr(pos+10);
pos = Str.indexOf("\r\n");
Str = Str.substr(0,pos);

return Str;
}

function getDNSs(host,DNS) {
if (DNS!="") DNS=" "+DNS;
var Str = WshShell.Exec("nslookup -querytype=ns "+host+DNS).StdOut.ReadAll();
var servers = [];
var pos = -1;
var tmp = "";

while (Str.indexOf("nameserver =")>-1) {
  pos = Str.indexOf("nameserver =");
  Str = Str.substr(pos+13);
  pos = Str.indexOf("\r\n");
  tmp = Str.substr(0,pos);
  Str = Str.substr(pos);

  servers.push(tmp);
}
  return servers;
}

Start cmd: cmd /c cscript /B /E:JScript %Script% %Params%
Script requires 1 or 2 parameters: <host name> [<DNS>]
E.g.:
google.com

[Celay]

Thanks for the script, gonna try it later to see if it works perfectly, gonna write again later.

Greetings,
Celay