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computer network internet security phần 9

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Đối tượng trẻ em được tạo ra trong một container mẹ thừa kế cho phép các đối tượng cha.Giấy chứng nhận kỹ thuật số Một hộ chiếu điện tử bao gồm một mô hình số, giá trị, quan trọng và được sử dụng để nhận dạng cá nhân. | The .rhosts file can be used to allow remote access to a system and is sometimes used by intruders to create easy backdoors into a system. If this file has recently been modified examine it for evidence of tampering. Initially and periodically verify that the remote host and user names in the files are consistent with local user access requirements. View with extreme caution a entry this allows users from any host to access the local system. An older vulnerability is systems set up with a single in the etc hosts.equiv file. This allows any other system to log in to your system. The should be replaced with specific system names. Note however that an intruder cannot gain root access through etc rhosts entries. ftp Files Directories which can be written to by anonymous FTP users are commonly used for storing and exchanging intruder files. Do not allow the user ftp to own any directories or files. System Executables in User Directories Copies of what may appear to be system executables in user directories may actually be an attempt to conceal malicious software. For example recent attacks have made use of binaries called vi and sed two commonly used Unix utilities. However these particular binaries were actually renamed intrusion software files designed to scan systems for weaknesses. System binaries found in unusual locations may be compared to the actual executable using the cmp command Determining if System Executables Have Been Trojaned SPI or Tripwire must be set up before an exposure in order to determine if your system executables have been Trojaned. Use your CD-ROM to make sure you have a good copy of all your system executables then run the above mentioned products according to the instructions that accompany them to create a basis for later comparison. Periodically run SPI or Tripwire to detect any modification of the system executables. etc inetd.conf Print a baseline listing of this file for comparison. Look for new services. etc aliases Look for unusual .