Forum Home
Press F1
Thread ID: 18196	2002-04-19 23:45:00	Selective blocking of PDF files	Guest (0)	Press F1

Post ID	Timestamp	Content	User
44678	2002-04-19 23:45:00	Hi Team I have been experiencing selective blocking of PDF files at various but not all sites. The error message states that I am not authorised to view that page. The problem is our old friend ZA Pro V3 (version 3.0.118) and more specifically, the 'Block mime type integrated objects' under Mobile Code Control. The solution is easy, just uncheck this item if a problem pops up but why does ZA differentiate between PDF sources? Is a mime integrated object just one of the ways to access PDF files and others are OK, or is this another bug? I favour the latter view at present because I have the 'Privacy Adviser' function enabled and although it usually tells me when something is being blocked, nothing comes up when these PDFs are blocked. Current problem source was a NZ Govt website but it happens on others when browsing via Google. It must have affected earlier versions of ZA as well because the effect is not a new one to me, it just seemed to have got worse lately. I had always wondered why authorisation seemed to be required on some sites yet I could open and read the HTML copy in Google. I figured that if access was genuinely denied it would have rejected web bots as well. Finding the short answer to this has opened up previously closed opportunities in my surfing but has also twitched my curiosity control and I'm looking for explanations. Cheers Billy 8-{)	Guest (0)
44679	2002-04-20 10:02:00	So that's why I'm not allowed to access some of the PDF pages I've tried looking at. I thought it was because they wanted me to cough up dosh for the privilege. Duh! I thought it was strange that there were no boxes to enter a credit card number in.... Aren't using ZoneAlarm though. Just installed Outpost this week to try that but I'm pretty sure some sites still wouldn't let me look at the files 'without authorisation' prior to Outpost. Oh well, at least I'm a bit wiser now.	Guest (0)
44680	2002-04-20 12:18:00	Thank god you're out there Susan. I though I'd outstayed my welcome and nobody wanted to talk to me. Tricky thing posting questions when you already know most of the answer, but I was hoping an expert would tell me what to do. I didn't win Lotto either! Cheers Billy 8-{)	Guest (0)
44681	2002-04-21 03:18:00	ZA might not like it because a PDF file is a 'sort of script file' --- it's actually executable code for the Adobe reader. So is Postscript code executable code (from which PDF is descended) --- you can write very powerful programmes in PostScript. (There are Internet myths about the CIA and NSA getting special code inserted in the interpreters of PostScript printers exported to 'At Risk' countries, so that the printers can take down the defence computing networks of those countries when the US wants to invade or bomb them). All PostScript files actually do contain a password which is checked by the interpreters. Some pages give the 'you are not authorised to view this page' message because the sites don't want you going directly to pages; they want you to go down from the home page, or the directory permissions 'just happen' to be set that way. I had that a few minutes ago: I was looking for some documentation which I knew was in the same place as some PDF pages which I had printed a week or two ago. I had noted the partial path to the page as : 'www.blah.blah.edu/DataSheets/'. I got that message. I knocked the directory name off the URL, and got to the home page. I walked down the site with no problem. (I can also get directly to the list of PDF files by giving the URL as .../DataSheets/microchipreferencesheets.html) . You can see why I didn't want to type all of that. I had to get a special setup file for Ghostscript from an Australian site (Linux PostScript interpreter, which can read PDF) because PDF files can be encrypted. The US export restrictions meant that the interpreter could not read any PDF files (even those not encrypted) without that setup file. In case you wondered, the Postscript password is the numeric value 0. I don't think it was ever proprly implemented, so the interpreters recognise the null value. It has been implemented for PDF. The files can be encrypted, and you need the real passowrd to read the file. (This requirement would come later, after you have actually got the file).	Guest (0)
44682	2002-04-21 09:22:00	Ah, now I know! That is really heavy stuff and I'm glad to hear that it is a 'myth' that the CIA arranged to be able to take down the defence computing networks of At Risk countries whenever they wanted. After all, we never know when NZ might be considered 'At Risk', do we? Now, I wonder what you are going to do with a file by the name of 'DataSheets/microchipreferencesheets.html'? Or maybe I won't ask... ;-)	Guest (0)
44683	2002-04-21 12:15:00	Thank you Graham It all makes sense now. I didn't realise PDFs were executable code but now that I know I'll not be so bothered when I get the run-around. See Susan? I just knew that there would be a real expert out there somewhere. Press F1 rules! Cheers Billy 8-{) (CIA please note, I am non-executable)	Guest (0)
1