sendmail cho phép người dùng tin cậy, được phép giả mạo thư được gửi đến máy địa phương. sendmail có thể được biên dịch trong chế độ gỡ lỗi, "một chế độ mà trong quá khứ đã được sử dụng để cho phép bên ngoài truy cập không hạn chế để sendmail hệ thống đang chạy trên. sendmail được sử dụng để chấp nhận mail | Chapter 17 Primary UNIX Network Services sendmail supports a wizard s password set in the configuration file that can be used to get a shell on a remote system wi Simpo PDF erge and Split Unregistered Version - http sendmail allows trusted users who are permitted to forge mail that is delivered to the local machine. sendmail can be compiled in debug mode a mode that in the past has been used to allow outsiders unrestricted access to the system sendmail is running on. sendmail used to accept mail with a program as the recipient thus allowing remote users to invoke shells and other programs on the destination host. sendmail has done a poor job of validating its arguments thus allowing users to overwrite arbitrary locations in memory or provide input that results in very bad side effects. One of the main reasons for sendmail s problems is its all-in-one design. The program is extremely complicated runs as superuser freely accepts connections from any computer on the Internet and has a rich command language. We are not surprised that the program has been plagued with problems although it seems to have had more than its share. Fortunately there are alternatives. Instead of having a large all-in-one program receive messages from the Internet and then deliver the mail you could split this functionality into two different programs. The Firewall Toolkit from Trusted Information Systems contains a program called smap that does exactly this. Even if you do not have a firewall you may wish to use smap for accepting SMTP connections from outside sites. For instructions on how to do this see Installing the TIS smap smapd sendmail Wrapper in Chapter 22. What s My sendmail Version If you are using the version of sendmail that was supplied with your operating system then you may have difficulty figuring out which version of sendmail you are actually running. Your sendmail program should print its version number when you telnet to it port 25 . Beware if .
