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Zm được định nghĩa là tập hợp {0, 1, , m-1}, được trang bị phép cộng (ký hiệu +) và phép nhân (ký hiệu là ×). Phép cộng và phép nhân được thực hiện trong Zm tương tự như trong Z, ngoại trừ kết quả tính theo modulo m Ví dụ: Giả sử ta cần tính giá trị trong Z16. Trong Z, ta có kết quả của phép nhân 11 ×13=143 Do 143≡15 (mod 16) nên 11 ×13 = 15...

43 trang | Chia sẻ: vutrong32 | Ngày: 16/10/2018 | Lượt xem: 1529 | Lượt tải: 0

SATAN SATAN could improve the security of a network by performing penetration testing To determine the strength of the security for the network and what vulnerabilities may still have existed SATAN would: Recognize several common networking-related security problems Report the problems without actually exploiting them Offer a tutorial that ex...

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Protocol Analyzer Also called a sniffer Captures each packet to decode and analyze its contents Can fully decode application-layer network protocols The different parts of the protocol can be analyzed for any suspicious behavior

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Remote Access Policies Establishing strong remote access policies is important Some recommendations for remote access policies: Remote access policies should be consistent for all users Remote access should be the responsibility of the IT department Form a working group and create a standard that all departments will agree to

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Physical Access Log A record or list of individuals who entered a secure area, the time that they entered, and the time they left the area Can also identify if unauthorized personnel have accessed a secure area Physical access logs originally were paper documents Today, door access systems and physical tokens can generate electronic log documen...

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Online Certificate Status Protocol (OCSP) A client server model A client program actually queries a server to see if someone’s certificate is valid. This way the client does not need to know how to find the CRL for the given certificate Authority and doesn’t have to actually search through the CRL.

81 trang | Chia sẻ: vutrong32 | Ngày: 16/10/2018 | Lượt xem: 1484 | Lượt tải: 0

Generally when I digital sign something. I don’t encrypt the whole message. Instead Run message through hash algorithm, generated message digest Sign the “message digest” Send both the original message and the encrypted message digest

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Rogue Access Point Discovery Tools Wireless protocol analyzer Auditors carry it around sniffing for rogue access points For more security, set up wireless probes to monitor the RF frequency Types of Wireless Probes Wireless device probe Desktop probe Access point probe Dedicated probe

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Host Intrusion Detection Systems (HIDS) Monitors network traffic Detects and possibly prevents attempts to HIDS are software-based and run on a local computer These systems can be divided into four groups: File system monitors Logfile analyzers Connection analyzers Kernel analyzers HIDS compare new behavior against normal behavior

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Antispyware software will warn you when the hosts file is modified Using updated versions of DNS server software prevents older DNS attacks against the server But many DNS flaws cannot be patched Eventually: Switch to DNSSEC (Domain Name System Security Extensions) But DNSSEC is not widely deployed yet, and it has its own problems

80 trang | Chia sẻ: vutrong32 | Ngày: 16/10/2018 | Lượt xem: 1263 | Lượt tải: 0