At 09:06 AM 10/20/96 -0700, William Davidheiser <wgd@netcom.com> wrote:
Hi all. I want to try to write a re-mailer that will run on my ISP's UNIX shell account. I am familiar with Windows socket programming (C/C++) but have never done anything in the UNIX environment.
Any pointers on where I should start?
I'd start by looking at the existing remailers, and thinking about the problems they're trying to solve and the service objectives they have. Mixmaster code is easy to find, and I've got my own modified ghio2 somewhere under my web page (idiom.com/~wcs/remailer, probably). Freedom remailer is another Type 1. Nymservers are trying to solve a different, and harder, problem. Writing a remailer that solves a slightly different problem than the others is a good thing to do. For instance, a remailer that's useful at work, such as one that decrypts PGP mail and forwards it inside the domain, or one that only sends mail to the suggestion box account, could gain acceptance and help add respectability for remailers. I don't remember if code for the Winsock remailer is available, but it works by fetching mail from a POP3 server and remailing it out SMTP servers. Also, you could benefit from feedback from people who used to run remailers and have switched to other code or quit. The usual problem is abuse, whether it's spam posted to the net, mailbombing victims, or forging mail/postings from victims to lists/newsgroups that will generate flames in response. Any blocking code you can write is good - you definitely need to be able to block by source, destination, and Subject:, and grepping message bodies may help. Limiting source and destination to pre-approved lists is also a good feature. Good code for auto-detecting attacks would help, e.g. shutting down or blocking if you get more than N messages for a given source or destination in a given time period, with a tolerable user interface for the administrator. You also need to integrate with encryption - PGP is the obvious choice (it'll be _so_ much easier when PGP 3.0 comes out, as we've been saying for the last couple of years :-) but S/MIME or SSL may also be good. I'd recommend having the default behaviour be to refuse non-encrypted mail - otherwise, any eavesdropper can compromise your system. # Thanks; Bill # Bill Stewart, +1-415-442-2215 stewarts@ix.netcom.com # You can get PGP outside the US at ftp.ox.ac.uk Imagine if three million people voted for somebody they _knew_, and the politicians had to count them all.