Firewall Hell

[caddyman]

Firewalls are the bane of my existence at the moment.

Tomorrow we have a meeting and, despite having commissioned a paper for it before Christmas, we received the dread tome this afternoon together with an accompanying spreadsheet.

Not only is the paper late, but it is long, too.

Splendid...

So, with profuse apologies I e-mail the damned thing out only to find that our benighted firewall had other ideas. Oh, the document went fine, but the spreadsheet? Oh no.

So that's a print job and more apologies at the meeting tomorrow.

Rude word animal.

Comments

Re:

[romney.livejournal.com]

A firewall shouldn't know about attachments as it's more concerned with deciding if one IP address can talk to another.

It will have been somefing like a mailsweeper that inspects emails and their attachments, looking for viruses or blocking attempts to spread dancing baby movies etc.

Sometimes password protecting a spreadsheet will get it blocked because the sweeper then cannot peek inside to look for malicious Macro code.

Zipping them up won't help as mailsweepers are trained to look inside ZIP files and peer at their contents.

All this is getting boring, so here's a way you can sometimes blow up a mailsweeper with a ZIP file.

Edit a document in Word full of any single character and cut-and-paste like crazy till it's enormous, say 1 meg. Save it and Zip it. Tiny, isn't it? Now make lots of copies of that zipped file and Zip them. Repeat a few times. You end up with a single zip file that is not very big but represents oodles of megabytes of Word documents.

Post the zip file and see if your mailsweeper or the mailsweeper at the receiving end goes bang when it unpacks the lot to scan it and runs out of disk space.

Alas, new generations of these things know about this and code against it, but there's still the chance you'll manage to spoil an IT managers day.