October 25, 2006

Crafty Spammers

Filed under: T3city — pj @ 4:01 pm

Yesterday, T3city started receiving complaints from AOL about spam received from our mail servers. This is not so unusual – some of our users forward email to their @aol.com email address and whenever spam is forwarded and the user complains to AOL, AOL complains to us. Even though we aren’t the source of the spam, from AOL’s perspective, forwarded spam comes from our mail servers.

At first, I incorrectly assumed that, as often happens, one of our users was reporting the forwarded mail to AOL as spam. Usually when this happens, I figure out who is reporting the spam to AOL and ask them to turn off forwarding or stop reporting spam to AOL. Sometimes the AOL spam complaint messages we get don’t have enough information to figure who is reporting the spam, so I have to wait for a message that has a header I can use.

In this case, I never got a message I could use. The spam looked pretty obnoxious and the source was mostly systems in China. I decided to start blocking the IPs of the systems that were sending us the spam. A lot of the IPs were from one ISP in China that has some huge IP address allocations. Blocking the IPs slowed down the AOL spam complaints, but there were other IPs from all over the world sending spam through us to AOL addresses. (more…)

October 24, 2006

Lots of RAM for .Net Programs

Filed under: .Net,Programming — pj @ 1:27 pm

Developing in .net and C# is OK, but every little utility uses 20MB of RAM… it’s such a waste. I’ve got this little ping utility that is just a few files of C# code… the .net code isn’t much different than it would be in MFC (or a text base UI like curses for that matter). Internally, the program uses almost no RAM – just a list of hosts and a few settings and statistics for each host.

But my little .net app uses 19MB RAM and that’s for the “release” build. It makes .net apps easy to find in Task Manager, though…. just sort the process list by RAM usage – my ping utility is #2 (2nd to MSN messenger).

The same program in C would¬†¬†probably use less than 512 KB. In C++ with MFC I’d guess 2 MB or less. Using a Virtual Machine is supposed to be safer than running native code, but there sure must be a lot of room for exploits with an “extra” 17 MB or so of code (or something) loaded into RAM…

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