Allow only .txt native files in file upload c#

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Hi,

In my file upload control I can able to upload only txt file extension. Suppose if user change the file type from .exe to .txt and trying to upload I should not allow to upload it. Because of security reason. So .txt should be native. It should not be changed from other format to .txt. How to acheive this in c#?

Please help me.

Posted 31-May-13 3:41am

Member 7684075

Updated 31-May-13 3:42am

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Dave Kreskowiak · Answer 1 · 2013-05-31T04:43:00

You can't prevent the upload from happening. The user will be able to upload anything they want. The identification of an .EXE file comes on the server-side. There is no way to reliably determine if a file is native text, but you can look for the signature of an .EXE file in the first few bytes of the file. They all start with with "MZ".