From f1b71c9fe7dbb4886588a036399cf5ebe16b7c47 Mon Sep 17 00:00:00 2001 From: Jannis Hoffmann Date: Tue, 9 Jul 2024 11:44:11 +0200 Subject: removed top level directory --- sqmail-4.3.07/man/forgeries.7 | 104 ------------------------------------------ 1 file changed, 104 deletions(-) delete mode 100644 sqmail-4.3.07/man/forgeries.7 (limited to 'sqmail-4.3.07/man/forgeries.7') diff --git a/sqmail-4.3.07/man/forgeries.7 b/sqmail-4.3.07/man/forgeries.7 deleted file mode 100644 index 85cc947..0000000 --- a/sqmail-4.3.07/man/forgeries.7 +++ /dev/null @@ -1,104 +0,0 @@ -.TH s/qmail: forgeries 7 -.SH "NAME" -forgeries \- how easy it is to forge mail -.SH "SUMMARY" -An electronic mail message can easily be forged. -Almost everything in it, -including the return address, -is completely under the control of the sender. - -An electronic mail message can be manually traced to its origin -if (1) all system administrators of intermediate machines -are both cooperative and competent, -(2) the sender did not break low-level TCP/IP security, -and -(3) all intermediate machines are secure. - -Users of -.I cryptography -can automatically ensure the integrity and secrecy -of their mail messages, as long as -the sending and receiving machines are secure. -.SH "FORGERIES" -Like postal mail, -electronic mail can be created entirely at the whim of the sender. -.BR From , -.BR Sender , -.BR Return-Path , -and -.BR Message-ID -can all contain whatever information the sender wants. - -For example, if you inject a message through -.B sendmail -or -.B qmail-inject -or -.BR SMTP , -you can simply type in a -.B From -field. -In fact, -.B qmail-inject -lets you set up -.BR MAILUSER , -.BR MAILHOST , -and -.B MAILNAME -environment variables -to produce your desired -.B From -field on every message. -.SH "TRACING FORGERIES" -Like postal mail, -electronic mail is postmarked when it is sent. -Each machine that receives an electronic mail message -adds a -.B Received -line to the top. - -A modern -.B Received -line contains quite a bit of information. -In conjunction with the machine's logs, -it lets a competent system administrator -determine where the machine received the message from, -as long as the sender did not break low-level TCP/IP security -or security on that machine. - -Large multi-user machines often come with inadequate logging software. -Fortunately, a system administrator can easily obtain a copy of a -931/1413/Ident/TAP server, such as -.BR pidentd . -Unfortunately, -some system administrators fail to do this, -and are thus unable to figure out which local user -was responsible for generating a message. - -If all intermediate system administrators are competent, -and the sender did not break machine security or low-level TCP/IP security, -it is possible to trace a message backwards. -Unfortunately, some traces are stymied by intermediate system -administrators who are uncooperative or untrustworthy. -.SH "CRYPTOGRAPHY" -The sender of a mail message may place his message into a -.I cryptographic -envelope stamped with his seal. -Strong cryptography guarantees that any two messages with the same seal -were sent by the same cryptographic entity: -perhaps a single person, perhaps a group of cooperating people, -but in any case somebody who knows a secret originally held -only by the creator of the seal. -The seal is called a -.I public key\fR. - -Unfortunately, the creator of the seal is often an insecure machine, -or an untrustworthy central agency, -but most of the time seals are kept secure. - -One popular cryptographic program is -.BR pgp . -.SH "SEE ALSO" -pgp(1), -identd(8), -qmail-header(8) -- cgit v1.2.3