Dynamic DNS Update Script

Not all of our projects directly relate to web site design and development. We also do quite a bit of network management.

We ran into a situation recently where we wanted to implement Remote Web Access and VPN for a client, but the client had a dynamic IP address from their ISP instead of a static IP. It is a common enough situation, but with the fiasco last year when a misinformed judge handed over 23 domains to Microsoft resulting in the shutdown of over 5 million dynamic hosts, we have been very leery about using many dynamic DNS services.

Our alternative solution has been to run our own, using DnsMadeEasy‘s AnyCast DNS and dynamic host records under our own domain names.

However, most software clients for Windows for updating dynamic host records are either tied to a specific vendor that we do not use, are adware supported, require a license fee, or worst of all require JAVA to run.

After looking at the state of the market, we decided to write our own and release it to the world under the MIT license, which allows anybody to use it for commercial or non-commercial use and create derivative works, while maintaining our copyright and limiting our liability.

Our Requirements:

Use something already installed on a windows server by default
Store authentication information in a config file and not hardcode anything
Limit network traffic and only update when necessary
Work with DnsMadeEasy, our anycast DNS provider of choice
Be lightweight enough to run as a windows service or scheduled task
Passwords need to be obfuscated and not stored in clear text

The result is a script written in VBScript that runs using Microsoft Windows Script Host (either wscript or cscript). You can either cut and past the code below (click the box to expand it) or download the zip file below.

DDNS.VBS
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433	`' DDNS.VBS - Windows shell script to update dynamic dns hosted on DnsMadeEasy` `'` `' Author: Donn Bly @ DBLY Group, LLC - https://dbly.com` `' License: The MIT License (MIT)` `' =============================================================================` `'` `' Copyright (c) 2015-2016 DBLY Group, LLC [ https://dbly.com ]` `'` `' Permission is hereby granted, free of charge, to any person obtaining a copy` `' of this software and associated documentation files (the "Software"), to deal` `' in the Software without restriction, including without limitation the rights` `' to use, copy, modify, merge, publish, distribute, sublicense, and/or sell` `' copies of the Software, and to permit persons to whom the Software is` `' furnished to do so, subject to the following conditions:` `'` `' The above copyright notice and this permission notice shall be included in all` `' copies or substantial portions of the Software.` `'` `' THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR` `' IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,` `' FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE` `' AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER` `' LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,` `' OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE` `' SOFTWARE.` `'` `' =============================================================================` `'` `' Version History:` `'` `' Version 1.0.0 - Initial Release - May 14, 2015` `'` `' Background:` `'` `' I ran into a situation where I wanted to utilize dynamic DNS for a client` `' but every ddns update client I found for windows was either tied to a` `' specific vendor that I didn't use, was adware supported, required a` `' licence fee, or worse of all, required JAVA to run.` `'` `' I wasn't going to install java runtime on a server for just this function` `' and I wasn't going to buy a license for such a trivial function. So, I` `' decided to write my own.` `'` `' My Requirements:` `'` `' 1. Use something already installed on a windows server by default` `' 2. Store authentication information in a config file and not hardcode anything` `' 3. limit network traffic and only update when necessary` `' 4. work with DnsMadeEasy, my anycast DNS provider of choice` `' 5. be lightweight enough to run as a windows service` `' 6. passwords need to be obfuscated and not stored in clear text` `'` `' Usage:` `'` `' Before using with DnsMadeEasy, you must first create the host record in the` `' control panel, setting the Dynamic flag, and creating a record-specific` `' password. The control panel will generate the recordid which you will need` `' to configure the script. I HIGHLY RECOMMEND creating a unique password for` `' the host record, and not using your own control panel password.` `'` `' By default the config file is stored in the same folder as the script, but` `' the script allows you to specify the config file on the command line using` `' the /config: command line switch. This is useful if you want to store the` `' config file in a folder other than the script, which you may wish to do` `' because the config file is updated every time the script runs in order to` `' keep track of the public ip and the last time it was verified. From a` `' security standpoint, especially if running as a scheduled task, you may` `' wish to store the script in a secure folder where the user running it only` `' has read-only access, and put the config file in a folder where only the` `' user context in which the script is running has access.` `'` `' The other command line switches are only for initial configuration and are` `' pretty much self-explanatory:` `'` `' /username:{username} Your DnsMadeEasy Username` `' /recordid:{recordid} The Record ID for the dynamic host` `' /password:{password} The password for the dynamic host record.` `'` `' The switches update the config file, and the data is stored as a base-64` `' encoded string (not plain text, but not overly secure - thus the recommendation` `' of using the /config: switch for production use). Encryption of passwords is` `' a worthless exercise for something that runs as a script. It would be a` `' trivial exercise to hack the decryption routine out of the script, or throw` `' an echo statement to display the password after it has already been` `' decrypted. Please be secure and make use of the operating system's security` `' to prevent unauthorized access to the script and config file.` `'` `' Version 1.0.1 - Maintenance Release - July 5, 2015` `'` `' Changes to the DNS Made Easy API URL have required a maintenance release.` `'` `' To change the API URL, edit your ddns.config file and update the UrlWrite line` `'` `' Before:` `' UrlWrite=https://www.dnsmadeeasy.com/servlet/updateip` `'` `' After:` `' UrlWrite=https://cp.dnsmadeeasy.com/servlet/updateip` `'` `' No change to the script is necessary, but an updated version with the new URL` `' as default is available as version 1.0.1` `'` `' Version 1.0.2 - Maintenance Release - July 6, 2015` `'` `' Changes to the DNS Made Easy API URL have required a maintenance release.` `'` `' To change the API URL, edit your ddns.config file and update the UrlWrite line` `'` `' Before:` `' UrlRead=http://www.dnsmadeeasy.com/myip.jsp` `'` `' After:` `' UrlRead=http://myip.dnsmadeeasy.com/` `'` `' No change to the script is necessary, but an updated version with the new URL` `' as default is available as version 1.0.2` `'` `' Version 1.0.3 - Maintenance Release - August 24, 2016` `'` `' Changes to data returned by the the DNS Made Easy API URL have required a` `' maintenance release.` `'` `' We have observed the API intermitently returning whitespace in the form of` `' tabs and spaces after the IP address. The updated script strips non IPv4` `' characters before testing.` `Option` `Explicit` `Dim` `oConfig, sConfigFile, sCurrentIP, rc` `Dim` `UpdateConfigFlag` `Dim` `ConfigError` `Public` `oFSO, oXMLHTTP, oShell` `Const` `C_USERNAME = "eUsername"` `Const` `C_PASSWORD = "ePassword"` `Const` `C_RECORDID = "eRecordID"` `Const` `C_URLREAD = "UrlRead"` `Const` `C_URLWRITE = "UrlWrite"` `Const` `C_PUBLICIP = "PublicIP"` `Const` `C_LASTUPDATE = "LastUpdate"` `Const` `C_LASTVERIFY = "LastVerify"` `Const` `C_STATUS = "Status"` `Const` `C_STATUS_ERROR_READ = "Error` `On` `Read"` `Const` `C_STATUS_ERROR_UPDATE = "Error` `On` `Update"` `Const` `C_STATUS_OK = "Ok"` `Const` `C_CONFIG_FLAG = "[DBLYGROUP DDNS UPDATER "` `Const` `C_CONFIG_SUFFIX = "v1.0.3]"` `' While the default is to use Base64 Encoding, you can always replace the` `' following with something else for further obfuscation. Just remember that` `' the first character is the padding character and the overall length of the` `' string must be 65 characters.` `Const` `BASE64_TRANSLATION = "=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"` `UpdateConfigFlag =` `False` `ConfigError =` `False` `set oConfig = createobject("scripting.dictionary")` `set oFSO = CreateObject("scripting.filesystemobject")` `set oXMLHTTP = CreateObject("MSXML2.XMLHTTP.3.0")` `set oShell = CreateObject("WScript.Shell")` `' Set Up Default Configuration` `sConfigFile = ".\ddns.config"` `oConfig.Add C_USERNAME, ""` `oConfig.Add C_PASSWORD, ""` `oConfig.Add C_RECORDID, ""` `oConfig.Add C_URLREAD, "http://myip.dnsmadeeasy.com/"` `oConfig.Add C_URLWRITE, "https://cp.dnsmadeeasy.com/servlet/updateip"` `oConfig.Add C_PUBLICIP, ""` `oConfig.Add C_LASTUPDATE, ""` `oConfig.Add C_LASTVERIFY, ""` `' apply any command line overrides to the defaults` `If` `WScript.Arguments.Named.Exists("config")` `Then` `sConfigFile = WScript.Arguments.Named.Item("config")` `End` `If` `if oFSO.FileExists(sConfigFile) then` `set oConfig = getConfigFile( sConfigFile, oConfig )` `else` `UpdateConfigFlag =` `True` `end if` `If` `WScript.Arguments.Named.Exists("username")` `Then` `oConfig( C_USERNAME ) = WScript.Arguments.Named.Item("username")` `UpdateConfigFlag =` `True` `End` `If` `If` `WScript.Arguments.Named.Exists("password")` `Then` `oConfig( C_PASSWORD ) = WScript.Arguments.Named.Item("password")` `UpdateConfigFlag =` `True` `End` `If` `If` `WScript.Arguments.Named.Exists("recordid")` `Then` `oConfig( C_RECORDID ) = WScript.Arguments.Named.Item("recordid")` `UpdateConfigFlag =` `True` `End` `If` `If` `UpdateConfigFlag` `Then` `UpdateConfigFile sConfigFile, oConfig` `Wscript.StdOut.WriteLine "Config File Updated"` `End` `If` `if oConfig( C_USERNAME ) = ""` `Then` `LogError "ERROR: Username not specified. Use /username:{username} to set"` `ConfigError =` `True` `End` `If` `if oConfig( C_PASSWORD ) = ""` `Then` `LogError "ERROR: Password not specified. Use /password:{password} to set"` `ConfigError =` `True` `End` `If` `if oConfig( C_RECORDID ) = ""` `Then` `LogError "ERROR: RecordID not specified. Use /recordid:{recordid} to set"` `ConfigError =` `True` `End` `If` `If` `ConfigError` `Then` `Wscript.Quit(1)` `End` `If` `sCurrentIP = GetCurrentPublicIP( oConfig( C_URLREAD ) )` `if sCurrentIP = oConfig( C_PUBLICIP )` `Then` `oConfig( C_LASTVERIFY ) = FormatDateTime(Now)` `oConfig.Add C_STATUS, C_STATUS_OK` `elseif len( sCurrentIP )` `Then` `rc = PutCurrentPublicIP( sCurrentIP, oConfig )` `if rc = 0 then` `oConfig( C_PUBLICIP ) = sCurrentIP` `oConfig( C_LASTUPDATE ) = FormatDateTime(Now)` `oConfig.Add C_STATUS, C_STATUS_OK` `Else` `oConfig.Add C_STATUS, C_STATUS_ERROR_UPDATE` `end if` `Else` `oConfig.Add C_STATUS, C_STATUS_ERROR_READ` `end if` `UpdateConfigFile sConfigFile, oConfig` `if oConfig( C_STATUS ) = C_STATUS_OK` `Then` `wscript.quit 0` `Else` `wscript.quit 1` `end if` `' ----------------------------------------` `Function` `getCurrentPublicIP( sUrlRead )` `' use an http request to determine the outside, public ip address. Since` `' this script is designed around DnsMadeEasy, it defaults to their public` `' page.` `Dim` `IpRegex, sResponse, sReturn` `sReturn = ""` `Set` `IpRegex =` `New` `RegExp` `IpRegex.Pattern = "^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$"` `On` `Error` `Resume` `Next` `oXMLHTTP.Open "GET", sUrlRead,` `False` `oXMLHTTP.Send` `if oXMLHTTP.Status = 200` `Then` `sResponse = oXMLHTTP.responseText` `IpRegex.Pattern = "[^0-9\.]"` `IpRegex.Global =` `True` `sResponse = IpRegex.Replace( sResponse, "" )` `IpRegex.Pattern = "^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$"` `if IpRegex.Test( sResponse )` `Then` `sReturn = sResponse` `Wscript.StdOut.WriteLine "Public` `IP Address = " & sReturn` `Else` `LogError "Error` `Getting` `Public` `IP Address. Response = [" & sResponse & "]"` `End` `If` `Else` `LogError "Error` `Getting` `Public` `IP Address. Status = " & oXMLHTTP.Status` `End` `If` `getCurrentPublicIP = sReturn` `End` `Function` `Function` `PutCurrentPublicIP( sCurrentIP, oConfig )` `' update dns server with current ip address using an HTTPS GET request` `Dim` `sUrl, sResponse, lReturn` `sUrl = oConfig( C_URLWRITE ) _` `& "?username=" & oConfig( C_USERNAME ) _` `& "&password=" & oConfig( C_PASSWORD ) _` `& "&id=" & oConfig( C_RECORDID ) _` `& "&ip=" & sCurrentIP` `lReturn = 1` `On` `Error` `Resume` `Next` `oXMLHTTP.Open "GET", sUrl,` `False` `oXMLHTTP.Send` `if oXMLHTTP.Status = 200` `Then` `sResponse = oXMLHTTP.responseText` `if sResponse = "success"` `Then` `lReturn = 0` `Else` `LogError "Error` `Setting` `Public` `IP Address. Response = " & sResponse` `End` `If` `Else` `LogError "Error` `Setting` `Public` `IP Address. Status = " & oXMLHTTP.Status` `End` `If` `PutCurrentPublicIP = lReturn` `End` `Function` `Function` `getConfigFile ( sConfigFile, oDefaultConfig )` `' read config file, return dictionary object` `Dim` `oFile, sKey, oNewConfig, sBuff, sValue, i` `set oNewConfig = CreateObject("scripting.dictionary")` `For` `Each` `sKey in oDefaultConfig.Keys` `oNewConfig.Add sKey, oDefaultConfig(sKey)` `Next` `set oFile = oFSO.OpenTextFile(sConfigFile,1)` `sBuff = oFile.ReadLine` `if left(sBuff,len( C_CONFIG_FLAG)) = C_CONFIG_FLAG` `Then` `Do` `Until` `oFile.AtEndOfStream` `sBuff = oFile.ReadLine` `sKey = ""` `sValue = ""` `i = instr(sBuff,"=")` `if i then` `sKey = left(sBuff,i-1)` `sValue = mid(sBuff,i+1)` `' if key begins with a lower case "e" then we have encoded it` `if left(sKey,1) = "e"` `Then` `sValue = StringDecode(sValue)` `Else` `LogError "Unexpected Data: " & sBuff` `end if` `if len(sKey)` `Then` `if oNewConfig.Exists(sKey)` `Then` `oNewConfig(sKey) = sValue` `End` `If` `End` `If` `Loop` `Else` `LogError "Configuration File of Unexpected Format"` `Wscript.Quit(1)` `End` `If` `oFile.Close` `set getConfigFile = oNewConfig` `End` `Function` `Sub` `UpdateConfigFile( sConfigFile, oConfig )` `Dim` `oFile, sKey` `set oFile = oFSO.OpenTextFile(sConfigFile,2,true)` `oFile.WriteLine C_CONFIG_FLAG & C_CONFIG_SUFFIX` `For` `Each` `sKey in oConfig.Keys` `if left(sKey,1) = "e"` `Then` `oFile.WriteLine sKey & "=" & StringEncode(oConfig(sKey))` `Else` `oFile.WriteLine sKey & "=" & oConfig(sKey)` `End` `If` `Next` `oFile.Close` `End` `Sub` `Function` `StringDecode( sPayload )` `' Basic Base64 String Decode` `Dim` `sReturn, Padding, Segment, c, ch(3), sHex, sOut` `sReturn = ""` `if len(sPayload)` `Mod` `4` `Then` `LogError "Decode` `Error: " & sPayload` `Exit` `Function` `End` `If` `For` `Segment = 1 to Len(sPayload)` `Step` `4` `Padding = 0` `For` `c = 0 to 3` `ch(c) = instr( BASE64_TRANSLATION, mid( sPayload, Segment + c, 1 ) ) - 2` `if ch(c) = -2` `Then` `LogError "Decode` `Error, Offset " & cstr( Segment + c ) & " : " & sPayload` `Exit` `Function` `ElseIf` `ch(c) = -1` `Then` `ch(c) = 0` `Padding = Padding + 1` `end if` `Next` `sHex = Right( "000000" & Hex( ch(3) + ch(2)&h40 + ch(1)&h1000 + ch(0)&h40000 ), 6)` `sOut = Left(Chr(CByte("&h" & Mid(sHex, 1, 2))) & Chr(CByte("&h" & Mid(sHex, 3, 2))) & Chr(CByte("&h" & Mid(sHex, 5, 2))),3 - Padding)` `sReturn = sReturn & sOut` `Next` `StringDecode = sReturn` `End` `Function` `Function` `StringEncode( sPayload )` `' Basic Base64 String Encode` `Dim` `Segment, c, ch(2), vSeg, sOut, sReturn, LastBlock` `sReturn = ""` `For` `Segment = 1 to len(sPayload) step 3` `for c = 0 to 2` `if Segment+c <= Len(sPayload)` `Then` `ch(c) = asc(mid(sPayload, Segment + c, 1))` `Else` `ch(c) = 0` `End` `If` `next` `vSeg = ch(2) + ch(1)&h100 + ch(0)*&h10000` `sOut = ""` `For` `c = 0 to 3` `sOut = mid( BASE64_TRANSLATION,(vSeg` `Mod` `64) + 2,1) & sOut` `vSeg = vSeg \ 64` `Next` `sReturn = sReturn & sOut` `Next` `' if payload doesn't translate evenly into a 24 bit block, replace extras with padding character` `LastBlock = 3 - len(sPayload) mod 3` `if LastBlock <> 3` `Then` `sReturn = left(sReturn, len(sReturn) - LastBlock ) & string(LastBlock, Left( BASE64_TRANSLATION, 1 ))` `End` `If` `StringEncode = sReturn` `End` `Function` `Sub` `LogError( sNotice )` `Dim` `oShell` `set oShell = CreateObject("WScript.Shell")` `' 0 SUCCESS` `' 1 ERROR` `' 2 WARNING` `' 4 INFORMATION` `' 8 AUDIT_SUCCESS` `' 16 AUDIT_FAILURE` `oShell.LogEvent 1, "[DDNS] " & sNotice` `Wscript.StdErr.WriteLine sNotice` `End` `Sub`

or download the program: ddns-1-0-3.zip (6935 Bytes)

** August 24, 2016 Update **

Changes to data returned by the DNS Made Easy API URL have required a maintenance release.

We have observed the API intermittently returning whitespace in the form of tabs and spaces after the IP address. The updated script strips non IPv4 characters before processing.

If you have questions or comments, please contact us and we will get back to you.

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