无线网络安全英文课件2

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chap03 Communication Networks 无线网络通信英文课件

Message is broken into a series of packets Each node determines next leg of transmission
for each packet
Phases of Circuit Switching
Circuit establishment
Priorities can be used
Disadvantages of Packet Switching
Each packet switching node introduces a delay Overall packet delay can vary substantially
This is referred to as jitter Caused by differing packet sizes, routes taken and
varying delay in the switches
Each packet requires overhead information
Includes destination and sequencing information Reduces communication capacity
End devices that wish to communicate Each station munications Network:
A collection of switching nodes
Switched Network
packet Emulates a circuit in a circuit switching network
but is not a dedicated path

英文版04 IEEE 802.11无线网

3
infrastructure vs. ad-hoc networks
infrastructure network
AP
AP wired network AP: Access Point
AP
ad-hoc network
4
802.11 - Architecture of an infrastructure network

clear channel assessment signal (carrier sense) modulation, coding channel selection, MIB
MAC Management

PMD Physical Medium Dependent

PHY Management

Direct communication within a limited range

802.11 LAN
STA1
IBSS1
STA3
Station (STA): terminal with access mechanisms to the wireless medium Independent Basic Service Set (IBSS): group of stations using the same radio frequency
STA2
IBSS2 STA5
STA4
802.11 LAN
6
IEEE standard 802.11
fixed terminal mobile terminal
infrastructure network access point
application

英语关于网络的ppt

The dangers of online games
1
Now we are in the Internet era. First , we must admit that Internet makes our life more convenient.
Internet plays a very important role in modern life. It revolutionized our lives in many ways .
As we have not found, we will grow old.
Addicting to online games is a waste of time.
10
Addicting to online games is a waste of energy.
People spend so much time playing the computer games at the cost of their health .
8
• There are so many enticement (诱惑 ) that beyond our control!
Addicting to online games is a waste of money.
9
• People who spent more time on the game.
6
Positive effects • Internet is a window
on the world for children. • People all over the world can gathered together through the internet.

chap04 Protocols and the TCPIP Suite 无线网络通信英文课件

OSI Session Layer
Provides the control structure for communication between applications
Establishes, manages, and terminates connections (sessions) between cooperating applications
OSI Data link Layer
Provides for the reliable transfer of information across the physical link
Sends blocks (frames) with the necessary synchronization, error control, and flow control
Protocols aຫໍສະໝຸດ d the TCP/IP Suite
Chapter 4
Key Features of a Protocol
Syntax
Concerns the format of the data blocks
Semantics
Includes control information for coordination and error handling
each different type of application
Protocol Data Units (PDUs)
Common TCP/IP Applications
Simple mail transfer protocol (SMTP)
Provides a basic electronic mail facility

Wireless security - 无线安全技术

Wireless LAN SecurityToday and TomorrowBySangram GayalandDr. S. A. Vetha ManickamCenter for Information and Network SecurityPune UniversityTable of Contents1. Introduction (3)2. Wireless LANs (3)2.1 Types of Wireless LANS (3)Stack (4)2.2 Protocol2.3 The 802.11 Physical Layer (5)2.4 802.11 MAC layer (5)3. Security Features of Wireless LANs (6)3.1 Authentication (7)3.2 Association (7)3.3 Encryption and Decryption-The WEP Protocol (8)4. Known Attacks on WEP (10)Type of Attacks (10)Decryption Dictionaries (11)Message Modification (12)Message Injection (13)Authentication Spoofing (13)Message Decryption (14)Man in the Middle Attack (16)Tools available for attacking WLANs (16)Summary of 802.11 vulnerabilities (17)5. Countermeasures (17)5.1 Fake Access points or Honey Pots (18)5.2 Wireless Network Auditing (18)6. Future of Wireless LAN Security (18)6.1 Advanced encryption Standard (AES) (18)6.1 Temporal Key Integrity Protocol (TKIP) (18)6.2 802.1X and Extensible Authentication Protocol (19)References (20)1.IntroductionWireless LANs are a boon for organizations that don't have time to setup wired LANs, make networked temporary offices a reality and remove the wire work that goes on in setting LANs. They are reported to reduce setting up costs by 15%. But, with these benefits come the security concerns.One doesn't need to have physical access to your wires to get into your LANs now. Any attacker, even though sitting in your parking lot, or in your neighboring building, can make a mockery of the security mechanisms of your WLAN.If you don't care about security, then go ahead; buy those WLAN cards/ Access Points. But, if you do, watch out for the developments on the security front of 802.11.As this report and many such others tell, contrary to 802.11's claims, WLANs have very little security. An attacker can listen to you, take control of your laptops/desktops and forge him to be you. He can cancel your orders, make changes into your databases, or empty your credit cards.So, what is the remedy?Don't trust anybody!!!Think like an attacker and take proper countermeasures. Have dynamic system administrators. Those attackers won't be lucky every time! The key is, be informed!2.W ireless LANsWireless LANs (WLANs) are quickly gaining popularity due to their ease of installation and higher employee mobility. Together with PDAs and other mobility devices, they go on to improve the quality of life.2.1Types of Wireless LANSThe part of success behind the popularity of WLANs is due to the availability of the 802.11 standard from IEEE. The standard specifies operation of WLANs in three ways:•Infrastructure Mode: Every WLAN workstation (WS) communicates to any machine through an access point (AP). The machine can be in the same WLAN or connected to the outside world through the AP.•Ad Hoc Network Mode: Every WS talks to another WS directly.•Mixed Network Mode: Every WS can work in the above two modes simultaneously.This is also called the Extended Basic Service Set (EBSS)Fig2.1: Types of WLAN2.2Protocol StackThe protocol stack for WLANs was designed such that existing applications can use them with minor modifications. The top three layers of the stack are same as the other networks.Application LayerTransport LayerNetwork Layer802.11 MAC/Data-link Layer802.11 Physical Layer2.3 The 802.11 Physical LayerThe 802.11 physical layers modulate the data and send it over the air. Three popular standards have emerged since the inception of WLANs, 802.11a, 802.11b, and 802.11g. The comparison between the above standards are given in the following table.Parameter 802.11a 802.11b 802.11gSpeed54 Mbps11Mbps54MbpsFrequency Band 5 GHz 2.4 GHz 2.4 GHz Modulation OFDM DSSS OFDM Distance(Indoor) 18 mts 30 mts 30 mts Distance(Outdoor) 30 mts 120 mts 120 mts No. of simultaneous networks 12 3 3 Availability Came after 802.11b available Widely available in the market To hit the market by mid2002Comments No interference ; less distance due to high frequencies Interference from RF sources like cordless phonesInterference, backwardscompatible with 802.11bTable 2.1 Comparison between 802.11 a, b, g2.4 802.11 MAC layerThe MAC / datalink layer of 802.11(IEEE std., 1) specifies the following features: 1. CRC checksum 2. Fragmentation 3. Auto-Roaming 4. Authentication and Association 5. WEP (Wired Equivalent Security) ProtocolThe data-link layer level encryption was intended to perform Wired Equivalent Security, but attackers have proven all these claims false and hollow. In the subsequent sections, we shall consider the loopholes in WEP.3.Security Features of Wireless LANsA message traveling by air can be intercepted without physical access to the wiring of an organization. Any person, sitting in the vicinity of a WLAN with a transceiver with a capability to listen/talk, can pose a threat. Unfortunately, the same hardware that is used for WLAN communication can be employed for such attacks. To make the WLANs reliable the following security goals were considered:•Confidentiality•Data Integrity•Access ControlThe following security measures are a part of the 802.11 IEEE protocol:•Authentication•Association•EncryptionThe need of a client to be mobile brought in the separation of authentication and association processes. Since a client frequently changes AP boundaries, he can be authenticated to various AP at a given point, yet remains associated to his chosen one. Before a client gets associated to other, he must be first authenticated.Fig 3.1: Authentication & Association3.1Authentication802.11 specify two authentication mechanisms:1 Open system authentication2 Shared key authentication•Open system authenticationA client needs an SSID for successful Association. Any new client that comes in an EBSS area is provided with an SSID. This is equivalent to no security.Fig 3.2: Open System Authentication•Shared system authenticationThe client cannot authenticate himself if he doesn't have the WEP shared secret key. WEP protocol is used for encryption.Fig 3.3: Shared key authentication3.2AssociationAn SSID is used to differentiate two networks logically. To successfully associate to a WS, one must have the SSID of the other WS. This was not intended to be a security feature, and in fact SSID is sent in open in the beacon frame of the AP.3.3Encryption and Decryption-The WEP ProtocolThe WLAN administrator has an option (if the administrator decides to send the packets unencrypted) to make all the communication over the air encrypted, i.e. every frame that is below the Ethernet Header is encrypted using the WEP protocol. The WEP protocol has three components:• A shared secret key, k (40bit /104 bit): The fact that the secret key is shared helps reduce the load on AP, while simultaneously assuming that whoever is given the secret key is a trusted person. This shared key is never sent over the air.802.11 doesn't discuss the deployment of this key onto Work Stations. It has to be installed manually at each WS/AP. Most APs can handle up to four shared secret keys.•Initialization vector, IV (24 bit): IV is a per-packet number that is sent in clear over the air. This number is most effective if generated randomly, because it is used as one of the inputs to the RC4 algorithm. 802.11 don’t specify generation of IV. Infact, many cards generate IVs in linear fashion, i.e., 1,2,3…•RC4 algorithm, RC4 (IV, k): This algorithm is used to generate a key stream K, length equal to that of the message to be transmitted by the data-link layer. It takes the IV and k as inputs.Fig 3.4: Encryption & Decryption on WEP•EncryptionAn IV is chosen on a per-packet basis and is sent along with the Ethernet header.P = <M,c(M)>K = RC4(IV,k)C = P⊕KwhereM : Message to be sent; contains all layers upto the network layer P : PlaintextC : Cipher text transmitted over the air•DecryptionThe IV is extracted from the header and is used to find the K.P'=C⊕K = <M',(c(M))'>It is checked ifc(M')=(c(M))' and the plaintext, P' is accepted.4.K nown Attacks on WEPWEP is considered to be very vulnerable to attackers. Any attacker sitting in the parking lot of a building can attack the building's WLAN security. This is unlike the wired case whereby the attacker needs a physical access to the wires. The following known attacks have been employed on WEP.Type of AttacksThe following known attacks are known to be effective:•Passive Attacks1 Dictionary based attacks2 Cracking the WEP key•Active attacks1 Authentication Spoofing2 Message Injection3 Message Modification4 Message Decryption5 Man in the Middle AttackAs with other networks, the active attacks are riskier but provide greater powers to the attacker.Passive Attacks Active attacksNo risk involved RiskierNo need to be the part of networks, because the WLAN cards support monitor mode, whereby one can listen to the communication without being a part of the network The attacker has to first get into the network, before doing damagesThe attacker can only listen to whatever is going on. He can not fiddle with the network The attacker can interrupt, hijack and control the network at his willTable 4.1. Passive vs. Active attacksDecryption DictionariesThe attacker passively sniffs every packet of the victim. He keeps storing the ciphertext along with the corresponding IV. Whenever the same IV repeats, he has two ciphertexts for the corresponding IV. As shown in the figure he has C31,0 and C31,1 for K 31C31,1⊕ C31,0 = P31,1⊕ P31,0Using classical techniques it is possible to find a and b from a ⊕ b. Thus the attacker can get the knowledge of P31,0 ,P31,1 and K31 provided he has patience and resources to do it.IV Ciphertext1IV0 C0,.... ....IV31 C0,31.... ....IVN C0,NTable 4.2. A Decryption Dictionary3.3 Cracking the WEP key (The working of Airsnort)This passive attack is used to find the secret key, k. The attack is based on the premise that some weak IVs exist (Fluhrer et. al., 2 ), i.e. they reveal information of a byte x of k. The following facts/assumptions are used:•The first byte of plaintext is known, it happens to be 0xAA for ARP and IP packets. We thus know the first byte K1 of the key stream K.•K1 is enough to find the byte x of k.•All the bytes of k prior to x have been deciphered correctly.•The probability of finding byte x of k correctly is more than 0.05.We illustrate here, with an example, the working of the attack:1. We take a packet and keep its IV.2. There can be two cases (Function classify of crack.c of Airsnort, 5)•If it is not a weak IV we dump it.•If it is a weak IV, we find that it helps us in finding 6th byte of k3. We calculate the value of 6th byte (Function key Guess of it RC4.c of Airsnort, 5).We find out that this weak IV w.r.t 6th byte of k calculates k6 to 0x67. We keep this Value of k6 in a table (because the calculated value 0x67 may be wrong).4Such a table keeps filling. After sufficient entries, we find that the calculated value0x67 of k6 is correct because it occurred the maximum times.5 After finding all the bytes of k, we make a try on all the packets, used above, bydecrypting them and checking whether indeed, CRC(M) is consistent for all ofthem.(This step is same as the decryption method described earlier)Fig 4.1: Working of AirsnortValue Value Value Value Value Value ByteNo. ofk.... .... .... .... .... .... ....6 0x67 0xab 0x37 0x67 0x67 0x20.... .… .... .... .... .... ....Table 4.3. Working of AirsnortThe actual number of packets needed to crack the WEP key was not checked by us ,but reports say that it can be done in a matter of a few hours for 40-bit secret key and a matter of days for 104-bit secret key.Message ModificationThis active attack is used to change a particular part of the message M that is known to the attacker, along with its position in the packet. This field can be an email ID, HTML form.Fig 4.2: Message ModificationThe attacker doesn't need to have the knowledge of key stream K or the secret key k for the attack. The attack is based on the fact that CRC(M) is an unkeyed function of MMessage InjectionThe attack assumes that the attacker has a pair of K, IV. This pair can be reused over and over again without arousing suspicions, because there is no mechanism to check continuous repetition of IVs. Again the fact that CRC (M) is an unkeyed function of M.Fig 4.3: Message InjectionAuthentication SpoofingThis attack is another form of Message Injection. By sniffing the shared key authentication process, the attacker knows a pair of Plaintext (Random Challenge) and Cipher text (Challenge Response) and the corresponding IV. Thus he knows the required <IV, K> pair. This pair can be used for authentication purposes.Fig 4.4: Authentication Spoofing Message DecryptionThere are two methods of decrypting the message by active attacks.1. IP Redirection2. Reaction Attack• IP RedirectionThis attack is an extension to message modification. The attacker modifies the destination IP in the IP header of the packet. By doing this, the attacker sends a packet from WEP encrypted zone to No WEP Zone , where he holds a machine .Fig 4.5: IP RedirectionTo do this he has to make changes in the IP Header Checksum. In most cases the initial IP Checksum is not known although the attacker is assumed to have the initial destination IP address. So the attacker keeps sending packets with various values of checksum till he gets the packet across to his machine in No WEP Zone.We did a simulation of this attack. The number of packets required, as a function of initial and final destination IPs, before getting a hit is open for interpretation.•Reaction AttackThis attack only works for TCP Packets.If TCP checksum is valid w.r.t. to the checksum, an ack is sent, otherwise the packet is dropped silently. This attack is based on the receiver’s willingness to decrypt arbitrary cipher text and feed them to another component of the system that leaks a tiny bit of information about it's inputs. The attack is rightly called reaction attack as it works by monitoring the recipient’s reaction to our forgeries.Fig 4.6: Reaction AttackWe have coded a simulation that verifies the property of TCP checksum that if bits P i and P i+16 are complements of each other then putting complemented values into each, P i and P i+16 doesn't affect the TCP checksum. Thus, the attack works in following fashion:1. Take complements of C i and C i+16.2. Make appropriate changes in the CRC checksum (this is not to be confused with the IP or TCP checksums) of message, CRC (M), and send the packet to the recipient.3. There are two cases:1.ACK received: P i and P i+16} were complements of each other.2. No ACK: P i and P i+16 were same.We didn’t test the actual effectiveness of this attack.Man in the Middle AttackThis is a standard attack employed on all sorts of networks. In WLANs, the attack works in the following fashion:Fig 4.7: Man in the MiddleSteps in Man in Middle attack:1.The attacker sets up a fake AP near to existing AP using a WS to masquerade networklogons.2.The user connects, in error, to the fake AP, and enters username and password.3.The intruder collects data and informs user of incorrect password, then sleeps for fiveminutes, and successfully logs on to the real AP.Tools available for attacking WLANsThese are few of the tools that are available for attacking the WLANs:1. Airsnort (Linux) - cracks the WEP key.2. WEPCrack (Linux) - cracks the WEP key.3. NetStumbler (Windows) - finds the network parameters like, SSID, Channels, MACAddresses, Type of Encryption used, Vendor of the card, tells the default secret key of the vendor can be used with a GPS for locating APs.4. Kismet (Linux) - a WLAN sniffer5. Thc-Wardrive (Linux) - for war driving6. dsniff (Linux) - counterpart of NetStumbler7. dstumbler (FreeBSD) - counterpart of NetStumblerSummary of 802.11 vulnerabilitiesThe following 802.11 vulnerabilities come out on the basis of the known attacks •SSID is required for associating a WS to an AP, and it is in the beacon frame. So, anyone can get it easily.•IV size is very small.•Many vendors increase the IVs in a linear fashion(0,1,2,3..)•An IV that has occurred before is bound to occur after 2^{24} times, and infact after 5000 packets due to birthday paradox. This infact make the dictionary attack possible, because this translates to keeping a data of 2^{24}* 1500 = 16 GB.•The strength of stream ciphers is based on the fact that a same seed never repeats, while the contrary has been described in the above point.•Despite knowing that a secret key should be changed frequently, no known mechanisms have come for good key management.•Only four secret keys are generally used in a network simultaneously, that too, most people don't change them from the default key provided by the vendor.•CRC(M) is an unkeyed function of M, message.•In the next chapter, we have recommended ACLs, but even MAC address spoofing can fool them.5.CountermeasuresIf there are vulnerabilities, then there are their countermeasures also, which cannot overcome them fully but can protect to a great extent.Here are few countermeasures, which can help a lot in retaining security of WLAN.!Do not trust WLAN and work under the coverage of a VPN (Virtual Private Networks).!Maintain a good key management system, which changes the key before the sufficient no of packets required for cracking the key are transmitted.!Increasing the bit length of IV and secret key is also a partial solution.!Use of strong algorithm like AES!Making the checksum of the message a keyed function, using algorithms like HMAC: keyed Hashing.!Configuring AP for allowing only few MAC addresses, which are there in his Access Control Lists (ACLs).!Define the ACL depending upon Signal strength.!One must take care of the physical security also. You should take care that no unauthorized person gets access of your laptop or any Work Station, which is in the network because he can just copy the secret key.!Enable RADIUS or Kerberos authentication for workstation to Access Point.!Enable IPSec or Application level encryption for secure data communications5.1Fake Access points or Honey Pots.Honey pots are devices placed on the periphery of a network for luring attackers to compromise them. By making attackers send their energy and resources on honey pots, effectively the real network is protected. Wireless honeypots consist of devices that transmit fake beacon frames. These devices emulate hundreds of fake access points, this results that the attacker is confused and tries to connect to any one of the fake access points. The attacker activity can be logged and studied. This also protects the network from attackers by hiding the network behind a mask.5.2Wireless Network AuditingWireless network auditing is an important part of WLAN security policy. The network needs to be regularly audited for rouge hardware. In this method the network is scanned and mapped for all access points and WLAN nodes. Then this is compared with previous network map. Commonly available network mapping tools like netstumbler and wavelan-tool can be used to do this.Specialized tools such as Airsnort can be used for WEP cracking and auditing the network for weak keys, key reuse and WEP security settings. These methods include the same tests as those carried out by hackers for breaking into the network.6.Future of Wireless LAN Security6.1Advanced encryption Standard (AES)Advanced Encryption Standard is gaining acceptance as appropriate replacement for RC4 algorithm in WEP. AES uses the Rijandale Algorithm and supports the following key lengths "128 bit"192 bit"256 bitAES is considered to be un-crackable by most Cryptographers. NIST has chosen AES for Federal Information Processing Standard (FIPS). In order to improve wireless LAN security the 802.11i is considering inclusion of AES in WEPv2.6.1Temporal Key Integrity Protocol (TKIP)The temporal key integrity protocol (TKIP), initially referred to as WEP2, is an interim solution that fixes the key reuse problem of WEP, that is, periodically using the same key to encrypt data. The TKIP process begins with a 128-bit "temporal key" shared among clients and access points. TKIP combines the temporal key with the client's MAC address and then adds a relatively large 16-octet initialization vector to produce the key that will encrypt the data. This procedure ensures that each station uses different key streams to encrypt the data. TKIP also prevents the passive snooping attack by hashing the IV.TKIP uses RC4 to perform the encryption, which is the same as WEP. A major difference from WEP, however, is that TKIP changes temporal keys every 10,000 packets. This provides a dynamic distribution method that significantly enhances the security of the network.An advantage of using TKIP is that companies having existing WEP-based access points and radio NICs can upgrade to TKIP through relatively simple firmware patches. In addition, WEP-only equipment will still interoperate with TKIP-enabled devices using WEP. TKIP is a temporary solution, and most experts believe that stronger encryption is still needed6.2802.1X and Extensible Authentication ProtocolCombined with an authentication protocol, such as EAP-TLS, LEAP, or EAP-TTLS, IEEE 802.1X provides port-based access control and mutual authentication between clients and access points via an authentication server. The use of digital certificates makes this process very effective. 802.1X also provides a method for distributing encryption keys dynamically to wireless LAN devices, which solves the key reuse problem found in the current version of 802.11.Initial 802.1X communications begins with an unauthenticated supplicant (i.e., client device) attempting to connect with an authenticator (i.e., 802.11 access point). The access point responds by enabling a port for passing only EAP packets from the client to an authentication server located on the wired side of the access point. The access point blocks all other traffic, such as HTTP, DHCP, and POP3 packets, until the access point can verify the client's identity using an authentication server (e.g., RADIUS). Once authenticated, the access point opens the client's port for other types of traffic.7.ConclusionWireless LAN security has a long way to go. Current Implementation of WEP has proved to be flawed. Further initiatives to come up with a standard that is robust and provides adequate security are urgently needed. The 802.1x and EAP are just mid points in a long journey. Till new security standard for WLAN comes up third party and proprietary methods need to be implemented.8.References1.L.M.S.C. OF THE IEEE COMPUTER SOCIETY. Wireless LAN Medium Access Control(MAC) and Physical Layer (PHY) Specifications, ANSI/IEEE std. 802.11, 1999 edition.2.Fluhrer, Mantin, Shamir. Weakness in the key-scheduling algorithm of RC4.3.Stubblefield, Ioannidis, Rubin. Using the Fluhrer, Mantin and Shamir attack to breakWEP.4.Borisov, Goldberg, Wagner. Intercepting Mobile communications: The Insecurity of802.11 - Draft.5.About the AuthorsDr. S. A. Vetha Manickam, Head of TechnologyS. A. Vetha Manickam holds a PhD degree in Scientific Computing and Numerical Analysis from Indian Institute of Technology, Bombay. He has a Masters in Applied Mathematics from Anna University, Chennai, where his dissertation was in "Object Oriented Methodologies". He was a Fellow of National Board for Higher Mathematics (NBHM), Department of Atomic Energy (DAE), India during the doctoral and post doctoral degree. Dr. Manickam has extensive experience in implementing e Security for organizations and defining the Information Risk Management Policies. He has been doing secure code auditing for many banking applications. He has also been involved in development of cryptographic algorithms and PKI products for authentication, confidentiality, integrity and Digital Signature. He is also involved in cryptanalysis for mobile and Wireless LAN encryption algorithms. He has spearheaded development teams in iKey integration, desktop security development, vulnerability scanner development and incorporation of Digital Signature for the Enterprise solutions.Sangram S. Gayal, Information Security ConsultantSangram S. Gayal is Bachelor of Engineering in Electronics and Telecommunications from Government College of Engineering, Aurangabad. He currently is an Information Security Consultant with Network Security Solutions India Ltd. and Associate researcher at Center for Information and Network Security, University of Pune. He currently is researching on wireless LAN vulnerabilities and countermeasures.21。

Air Defense无线局域网安全和关键基础设施保护-PPT课件

窃听VoIP会话
7
破解WEP
破解WEP事件的发生频率
2019 不可破解 2019 数年一次 2019 数日一次 2019 几小时一次 2019 几分钟一次 2019 几秒钟一次
数十种攻击
密钥破解无重放保护消息完整性不够共享密钥 RC4实施不力
尽快从WEP升级至WPA2
8
破解WPA
破解WPA事件的发生频率
21
摩托罗拉AirDefense无线网络安全漏洞评估模块
模块描述 – 一种创新无线网络安全漏洞扫描工具，能够利用现有的WIPS传感器，模拟黑客身份，对无线网络进行主动测试
客户选择该模块的理由
– 在发生黑客攻击之前，主动查明网络安全问题 – 验证无线网络与持卡人数据彼此隔离 – 远程安全漏洞扫描，降低顾问和差旅费用 – 自动完成无线网络扫描模块功能 – 无线网络安全漏洞评估（7.3.4版）——查明客户无线网络中的安全漏洞模块价格 – 7.3.4或更高版本的附加模块 – 每个传感器的许可费为295美元，所有传感器必须单独购买许可证
现场办公室
Sensor
现场办公室
总部
创新附加模块
高级取证
检查详细的无线网络活动记录，进行取证分析和故障检测
无线网络漏洞评估
主动评估无线网络安全情况
移动办公人员保护
端点安全性，保护移动工作人员（不论他们身在何处）
高级排障
更快解决无线网络相关问题，主动解决问题
频率分析
查明和划分常见射频干扰类型，包括微波和蓝牙等
2
3
用户连接接入点
接入点向用户分发IP地址
用户终端
4
入侵终端（软AP）
5
扫描笔记本安全漏洞，然后发起攻击

wifi网络安全接入英文

wifi网络安全接入英文WiFi Network Security: Ensuring Safe Access to the InternetIn today's digital age, accessing the internet through WiFi has become a necessity for almost everyone. Whether it's in our homes, offices, or public places, WiFi allows us to connect our devices and access the world wide web seamlessly. However, as convenient as WiFi is, it also poses certain risks to our security and privacy. Therefore, it is essential to take necessary precautions to ensure a safe and secure WiFi network access.One of the primary concerns related to WiFi network security is unauthorized access. Hackers and malicious individuals often attempt to gain access to WiFi networks to snoop on users' activities, steal personal information, or launch cyber attacks. To prevent unauthorized access, it is crucial to set a strong, unique password for the WiFi network. Avoid using easily guessable passwords such as "password" or "123456" and choose a combination of letters, numbers, and special characters.Another important aspect of WiFi network security is encryption. Encryption ensures that the data sent and received over the WiFi network is scrambled and can only be deciphered by authorized devices. Most modern routers support various encryption protocols such as WPA2 (WiFi Protected Access 2) or WPA3, which provide a high level of security. It is recommended to enable encryption on your WiFi network and regularly update the encryption protocol as newer, more secure standards become available.Updating the firmware of your WiFi router is also crucial in maintaining network security. Manufacturers often release firmware updates to fix vulnerabilities and enhance security features. Regularly checking for firmware updates and installing them promptly ensures that your WiFi network is protected against the latest threats.In addition to securing the WiFi network itself, it is also essential to practice safe browsing habits. Be cautious when accessing sensitive information such as banking websites or entering personal details on unsecured websites. Look for the "https:// " in the website's URL, indicating that the connection is encrypted and secure. Using a reliable antivirus software on your devices can further enhance your protection against malware and other online threats.Lastly, being aware of the potential risks and staying informed about the latest security practices is vital in maintaining WiFi network security. Following reputable sources for cybersecurity news and regularly educating yourself about emerging threats can help you stay one step ahead of potential attackers.In conclusion, ensuring the security of your WiFi network is crucial for protecting your privacy and preventing unauthorized access. By setting strong passwords, enabling encryption, updating firmware, practicing safe browsing habits, and staying informed, you can significantly reduce the risks associated with WiFi network access.。

网络安全(英语版)ppt课件

；....
3
Maintain Network Security
Recently, the news that U.S attack on Chinese Internet is exposed. In the era of rapid development of network, we must take measures to protect our security of privacy and property effectively. we need to distinguish right from lots of websites. Furthermore, it is inevitable that some secure anti-virus soft wares can be installed.
最近的新闻都揭示了美国对中国网络的攻击。在网络飞速发展的时代，我们必须要采取有效的措施来保护我们的隐私和财产安全。我们需要在众多的网站之间明辨是非，此外，安装一些安全的杀毒软件是必须的。
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5
Hardware Security
Software Security
网络安全是指网络系统的硬件、软件及其系统中的数据受到保护，不因偶然Inf的or或ma者tio恶n意Se的c原uri因ty 而遭受到破坏、更改、泄露，系统连续可靠正常地运行，网络服务不中断。
网络安全包含网络设备安全、网络信息安全、网络软件安全。
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2
Influencing factors
•Network Topology factors
•Netw网or络k S结e构cu因rity素threats
网络安全威胁
网络基本拓扑结构有3种：星型、总线型和环型。在建造内部网时，

网络安全英语ppt

网络安全英语ppt 网络安全英语PPT：Slide 1:Title: Introduction to Network Security Introduction:- What is network security?- Why is network security important?- Common threats and vulnerabilities Slide 2:Title: Types of Network Security Measures 1. Firewalls:- Definition and purpose- How do firewalls work?- Types of firewallsSlide 3:2. Intrusion Detection Systems (IDS):- Definition and purpose- How do IDS work?- Types of IDSSlide 4:3. Virtual Private Networks (VPNs):- Definition and purpose- How do VPNs work?- Benefits of using VPNsSlide 5:4. Encryption:- Definition and purpose- How does encryption work?- Examples of encryption algorithmsSlide 6:5. Access Control:- Definition and purpose- Types of access control mechanisms- Best practices for access controlSlide 7:6. Authentication:- Definition and purpose- Types of authentication methods- Multi-factor authenticationSlide 8:Title: Best Practices for Network Security1. Regularly update software and firmware2. Use strong, unique passwords3. Enable two-factor authentication4. Implement regular data backups5. Monitor network trafficSlide 9:Title: Conclusion- Importance of network security- Key network security measures- Best practices to enhance network securitySlide 10:References:- Cite any sources and references used in the presentation Note: This PPT provides a basic outline for a presentation on network security in English. You may add more slides or modify the content according to your specific needs.。

网络安全主题班会课件 (一)(2)

不回拨
客服咨洵、详情请拨、专属通道一一陌生信息中提供联系方式,都不要轻易致电联系·
不点击不透露
免费领奖、视频相册、工作资料、低价抢购、升级下载、积分兑换．一、、只要是陌生网址,都不要点击.
手机号码、家庭住址、电子邮箱、亲属联系方式、身份证号、银行卡账号密码、网银登录支付密码、支付宝密码等一切个人以及亲友隐私信息通通不可泄露.
账号密码安全
设置浏览器安全等级.
我们常用浏览器都具有安全等级设置功能,通过合理地设置可以有效过滤一些非法网站访问限制, 从而减少对电脑和个人信息损害.
坚决抵制反动、色情、暴力网站.
下载软件和资料时应选择正规网站或官方网站.
不要随意点击非法链接.
第三部分
手机上网安全
关注网络安全
防止网络诈骗
安全上网
YOUR LOGO
ELECTRONIC NETWORK SECURITY
电子网络安全
关注网络安全/防止网络诈骗安全上网主题班会PPT
老师:哇哇哇
@
Checkout
PAY NOW
@
!@
前言
“互联网+”时代改变了人们生活习惯和行为模式 ——购物交易、社交娱乐、学习工作,
方方面面需求都可以通过互联网来完成.
不转账
房补、车补、中奖、退税、银行卡积分兑换现金等不要贪,身份不核实清楚不转账.
核实转账请求
他人要求借钱、打款、线上支付、充值等 , 所有现金往来一定要当面或电话联系本人确认.
陌生可疑短信、电话、 QQ、微信、邮件、通知等 , 只要拿不准情况,都通过线下营业厅、官方网站等官方渠道核实.

无线网络安全英文课件

第六页，编辑于星期五：九点五十二分。
Breach of Security Levels of Impact
High
• The loss could be expected to have a severe or catastrophic adverse effect on organizational operations, organizational assets, or individuals
• Security mechanisms typically involve more than a particular algorithm or protocol
• Security is essentially a battle of wits between a perpetrator and the designer
Availability
• Assures that systems work promptly and service is not denied to authorized users
第四页，编辑于星期五：九点五十二分。
CIA Triad
第五页，编辑于星期五：九点五十二分。
Possible additional concepts:
patient and expose the hospital to massive liability
A Web site that offers a forum to registered users to discuss some specific topic
would be assigned a moderate level of integrity
A moderate availability requirement is a public Web

无线网络安全简介 ppt课件

WLAN
Outline
1
基本概念介绍
2
WEP
3
WAP1
4
WAP2
5
WAPI
Outline
1
基本概念介绍
2WEP3WAP14WAP2
5
WAPI
何谓WLAN ？
WLAN（Wireless LAN）就是无线局域网络，一般來讲，所谓无线，顾名思义就是利用无线电波作为媒介的传送信息。
WLAN的工作方式
WEP
✓RC4算法的密钥空间存在大量弱密钥, 数据帧的前面两个字节为头部信息, 是己知的, 将明文和密文异或可获得密钥流,根据IV和密钥流的前两个字节, 可以判断该密钥种子是否为弱密钥. ✓获得足够多的弱密钥, 可以恢复出WEP的共享密钥“WEP 破解工具Airsnort利用弱密钥可以在分析100万个帧后即可破解RC4的40位或104位密钥, 经过改进,在分析2万个帧后即可破解RC4密钥, 在正常使用情况下, 仅需十几秒的时间 ”.
WEP
✓WEP设计了综合检验值ICV进行完整性保护,来防止非法篡改和传输错误,使用CRC犯算法实现"但CRC32是线性运算,是设计用来检测消息中的随机错误的,不是安全杂凑函数 ,并不具备密码学上的安全性.
WEP密钥管理问题和重放攻击
✓WEP没有定义有效的密钥管理和分配机制,手动管理密钥效率低下,过程繁琐,并存在很大的安全隐患"只要有任何成员离开公司,那么就应该重新分配密钥,且一旦密钥泄露,将无任何秘密可言"
WEP鉴权
共享密钥验证
➢ 客户发出验证请求 ➢ AP产生一个考卷，并发送给客户端 ➢ 客户端使用WEP密钥加密数据包并且将它发回 ➢ AP 解密数据包并且同原始试卷比较 ➢ AP 向客户端发出成功信息

无线网络安全技术第二讲PPT教案

英文中字母的使用频率
频率 14
E使用最多；然后是T R N I O A S 其他字母使用较少
最少的是J K Q X Z
12
10
8
6
4
2
0 A B C D E F G H I J K L MN O P Q R S T U V WX Y Z
基于语言统计规律的破译
பைடு நூலகம்
1 密文：
UZQSOVUOHXMOPVGPOZPEVSGZWSZOPFPESX UDBMETSXAIZVUEPHZHMDZSHZOWSFPAPPDT SVPQUZWYMXUZUHSXEPYEPOPDZSZUFPOMBZ WPFUPZHMDJUDTMOHMQ
字母a b c d… x y z分别由数字0 1 2 3 …24 25表示；
加作密密用文时下字向：母后C明i。移文位字d母（PKi在i）密，钥得K到i的解作明密用文时下字向：母前P密i。移文位字d母（CKi在i）密，钥得K到i的
维基尼亚表：26x26矩阵表示26 种排列组合
举例
Standard Vigenere Table
栅栏技术：按照对角线的顺序写入明文，而按行的顺序读出作为密文。
明文： meet me after the party
写为： m e m a t r h p r y
e t e f eteat
密文：mematrhpryetefeteat
更复杂的例子：
密钥： 4 3 1 2 5 6 7 明文： a t t a c k p
2direct contacts have been made with political
0representatives of the viet cong in moscow

Chap6_2_WLAN_2 Wireless Networks and Security 无线网络与安全教学课件

First, the use of the Extensible Authentication Protocol (EAP) and 802.1x enforces user authentication and mutual authentication.
Second, Message Integrity Code (MIC) detects modifications of bits during transmission.
The checksum is a non-cryptographic value. Some known attacks, such as side-channel
attacks, can compromise the data’s integrity.
Chap 6.2- Dr. Du
13
MAC Address Spoofing
Standard (AES) for new WLAN implementations.
Chap 6.2- Dr. Du
15
IEEE 802.11 Standards
802.11i - The 802.11i specification consists of three main
pieces organized into two layers. On the lower level are:
The standards address performance and security concerns within the wireless realm, including
802.11b, 802.11a, 802.11g, and later: 802.1x, 802.11i.

Chap4_1_WSN_Intro_Routing Wireless Networks and Security 无线网络与安全教学课件

However, key differences exist
▪ Energy constraint in sensor networks ▪ Traffic models and characteristics ▪ Other issues like coverage, fault-tolerance, etc.
Event
D Src
C
M A
B
Sink
Chap. 4.1 - Dr. Du
Link A-M lossy A reinforces B B reinforces C … D need not A (–) reinforces M M (–) reinforces D
16
Loop Elimination
networking to it.
Chap. 4.1 - Dr. Du
5
However …
Ad Hoc and Sensor Networks are both multihop wireless architectures
▪ Thereby shares several technical issues and challenges ▪ Solutions in one domain often applicable to others.
Chap. 4.1 - Dr. Du
4
AdHoc and Sensors …
Ad Hoc network lacking killer applications
▪ Difficult to force co-operation among HUMAN users ▪ Mobility/connectivity unreliable for a business model ▪ Difficult to bootstrap – critical mass required