Showing posts with label OSI layer model. Show all posts
Showing posts with label OSI layer model. Show all posts

Wednesday, 4 April 2012

ICND1 CRAMM SHEET

QUICK Reference (ICND 1)


Protocol :- Predefined set of rules to communicate


Network Applications
  • Email
  • Collaboration 
  • Messaging 
  • Web Browsing 
  • Databse applications
Speed = Data Rate 
Availability  = Likelihood network is avialable 
Scalability= How well network can scale 
Topology= Physical components  of network like cable, switches, router

  
Network Security (Type of Attacks)
 
Passive attack :- Sniffing aata like capturing password on the wire or wireless
Active attack :- Actively try to invade security , adding malicious code
Inside attack:- Attack from authorised users
Close in Attack :- Attack with in close physical proximity
Distribution:- Attack launched during distribution phase of any hardware of software. 

Network Security Process 

Security is  ever evolving process 
  1. Secure 
  2. Monitor 
  3. Test
  4. Improve 
 
Reconnaissance attack(Gathering Information like sniffing data , Ping Sweep)
Access Attack
  • Password Attack 
  • Trust Exploitation
  • Port Redirection
  • Man-in-the Middle
  • Buffer Overflow.
Application Layer Attack 
  •  Exploiting well known weekness in the software
  • Trojon programms that loggs the key. 
  • Password stealing
  •  Java or activeX codes that work maliciously
Managament / Monitoring Protocols
  • Telent (but information is sent in Plain txt) 
  • SSH (secure encrypted communication)
  • Secure Socket Layer (SSL)
  • Monitoring Protocols (SNMP, syslog, NTP, TFTP)
OSI Reference Model  
 
All People Seem To Need Data Processing
 
TCP UDP = Transport Layer 
Router, ICMP, IGMP, IP = Network Layer 
802.3 802.2 Framerelay, HDLC = Data Link Layer

Data  = Application Layer
Segment = Transport Layer
Packet = Network Layer
Frames = Data Link Layer
Bits = Physical Layer

TCP  = Connection Orieneted  (More overheads, Confrmation of delivery)
IP, UDP= Connection Less (best effort, no recovery of lost packet)

CLASS of IP Address 



CLASS A: 1.0.0.0 to 126.0.0.0
Class B: 128.0.0.0 to 191.255.0.0.
Class C: 192.0.0.0 to 223.255.255.0.
Class D: 224–239
Class E: 240 - 255


RFC 1918 Private IP Address Range

–10.0.0.0 to 10.255.255.255
–172.16.0.0 to 172.31.255.255
–192.168.0.0 to 192.168.255.255 

IPV6 

16 Octet
128 Bits
A524:72D3:2C80:DD02:0029:EC7A:002B:EA73 
 
 
TCP Header 
URG: Urgent Pointer field significant
ACK: Acknowledgment field significant
PSH:  Push Function application need data to be pushed immediately
RST:  Reset the connection
SYN:  Synchronize sequence numbers
FIN:   No more data from sender 
 
PORTS
  • ü  0 to 1023 are well-known ports.
  • ü 1024 to 49151 are registered ports
  • ü 49152–65535 are unregistered
 TCP/IP Applications
FTP = TCP based File transfer (TCP 21 Port)
TFTP= UDP based used to transfer Cisco IOS or configuration  (UDP 69 Port)
Telnet= Terminal Emuletion Command line  (TCP 23)
SMTP= Email delivery (TCP 25)
SNMP= Network Manamgement Protocol.  (UDP 161)
DHCP= Assign IP address automatically
DNS= Name to IP resolution  (Both TCP, UDP 53)

TCP 3 Way HandShake 
 

LAN Traffic Types 

  • Unicast (one to one communication)
  • Broadcast (one to any Communication)
  • Multicast (from one to Subnet of users)
Address Translation 

Inside local address =IP address assigned to a host on the inside network

Inside global address= A public IP address assigned by the ISP that represents one or more inside local IP addresses to the outside world.

Outside global address = IP address assigned to a host on the outside network

Outside local address = IP address of an outside host as it appears to the inside

When a host on an Ethernet LAN has information to send, the following steps are taken:1. A device with a frame to send listens until Ethernet is not busy CSMA/CD.
2. When the Ethernet is not busy, the sender begins sending the frame.
3. The sender listens to make sure that no collision occurred.
4. Once the senders hear the collision, they each send a jamming signal, to ensure that all
stations recognize the collision.
5. After the jamming is complete, each sender randomizes a timer and waits that long.
6. When each timer expires, the process starts over with step 1.
 
 
MAC Address
  • Layer 2 address 
  • Hexa Decimal Formate 
  • 48 Bits = 24 bits of Vandor ID + 24 bits of Unique ID
 
 Wireless
 IEEE 802.11a: 54 Mbps in the 5.7 GHz ISM band
 IEEE 802.11b: 11 Mbps in the 2.4 GHz ISM band
 IEEE 802.11g: 54 Mbps in the 2.4 GHz ISM band

 IEEE 802.11n: 300 +Mbps in the 2.4 and  5GHz ISM band

Wireless Security

  • WEP (Basic Enryption , not good)
  • 802.1x EAP  (Use dynamic Keys, User authentication)
  • WPA WiFi Protected access
  • WPA2 (Most Strongest uses AES for Encryption)
Configuring Port Security on Switch

SwitchX(config)# interface fa0/5
SwitchX(config-if)# switchport mode access
SwitchX(config-if)# switchport port-security
SwitchX(config-if)# switchport port-security maximum 1
SwitchX(config-if)# switchport port-security mac-address sticky
SwitchX(config-if)# switchport port-security violation shutdown


Keypoints
  • Switches increases the number of collisions domains in the network
  • Switches are multiport bridges that allow you to create multiple broadcast domains 
  • Switches and bridges work on L2 
  • Primary functions of a router are: Packet Switching and Path Selection
  • A straight-through cable is used to connect two different devices
  • Layer 4 functions are error recovery and flow control
  • Transport layer provides reliable networking via acknowledgments, sequencing,
    and flow control.
  • HTTPS is the secured version of the HTTP application, which normally uses 128 bit SSL
    encryption to secure the information uses port 443
  • VOIP systems utilize UDP because it is faster and uses less overhead
  • Spanning-Tree Protocol (STP) is a Layer 2 protocol
  • STP is used to avoid switching loops 
  • CDP is a device discovery protocol that runs over Layer 2
  • Crossover cable is used to connect two of the same device types
  • 100BaseT  (UTP, STP) has a distance restriction of 100 meter or 328 Feet
  • IEEE 802.3z standard describes 1000BASE-SX (Gigabit Ethernet)
  • Switches forward broadcast but routers do not forward broadcasts (by default)
  •  RIPv2 carries subnet mask information allowing for VLSM
  • For point to point Link  /30 IP address is used.
  • Network Address Translation (NAT) can be used to hide the private IP addressing
  • NVRAM-Nonvolatile RAM stores the initial or startup configuration file.
  • 0x2102, is the normal config-register

Monday, 20 June 2011

CISSP CBK 4 Telecom and Network security


Forth domain as under.

Telecom and Network security

Quarter Inch Cartridge drives (QIC). This format is mostly used for home/small office backups, has a small capacity, and is slow, but inexpensive.

Digital Linear Tape (DLT) is only 0.498 inches (8mm Tape format) in size, yet the compression techniques and head scanning process make it a large capacity and fast tape the QIC and DAT 5Mbps. Digital Audio Tape (DAT)

LTO (Linear Tape-Open) open-format technology and storage in TB

Application: Gateway

Presentation: encryption, compression, formating

Session:

Transport:

Network: Router

Datalink: Bridge, Switch

Physical: Repeater

Amplitude (height of the signal)

Frequency (number of waves in a defined period of time)

Digital signals are more reliable to be used over a longer distance because can easily be extracted from noise and retransmitted and it has only two possible discrete values 1 and 0

ASynchronous communication sender can send data at any time, and the receiving end must always be ready. (Modem use start and stop bit Asynchronous)

Synchronous communication takes place between two devices that are synchronized usually via a clocking mechanism (Remember synchronous Token was time based access control)

Baseband uses the entire communication channel for its transmission, Ethernet is a baseband technology that uses the entire wire for just one channel.

Broadband divides the communication channel into individual and independent channels.

***Important to note that node authentication, by itself, should not be used to establish trustworthiness of a user within the network.

Fast Ethernet uses the traditional CSMA/CD

wireless LAN technology, 802.11, usesCSMA/CA for its media access functionality.

Token Ring IEEE 802.5 standard. Each computer is connected to a central hub, called a Multistation Access Unit (MAU) 16 Mbps Speed

UTP Categories Cat 1 voice grade Cat 2 Data 4 Mbps Cat 3 10 Mbps for Token ring Cat 4 16 Mbps Cat 5 100 Mbps and Cat 5E 1 Gbp.

Polling LAN media access method setup primary and secondary station primary ask secodary if it need to transmit.

MAC to IP address ARP

IP to MAC = RARP

Attackers alter a system’s ARP table so it contains incorrect information known ARP table poisoning. The attacker’s goal is to receive packets intended for another computer. This is a type of masquerading attack

Wires are encapsulated within pressurized conduits so if someone attempts to access a wire, the pressure of the conduit will change, causing an alarm to sound.

Class D multicast uses IGMP protocol.

DHCP Discover, client searches for the present DHCP Server

DHCP Offer, Server offer a client an available IP address

DHCP Request, Client Confirms accepting allocated setting

DHCP Pack. ack that ip address has been allocated with lease time.

DHCP snooping ensures that DHCP servers can assign IP addresses to only selected systems, identified by their MAC addresses

RARP The diskless machine hold mac adress it broadcast the information for a specific hardware address and RARP Server reponds with IP address

RARP evolved into BOOTP, which evolved into DHCP.

ARP knows the IP address and broadcasts to find the matching hardware address, the MAC address. RARP knows the hardware address and broadcasts to find the IP address

Loki attack ICMP status packet is stuffed with data as well

Routers usually do not pass broadcast information, but bridges do pass broadcast information

e-mail gateway convert the message into a standard that all mail servers understand X.400

phreaker (a phone hacker)

Types of Firewalls

1. Packet filtering simple ACL based (Network Layer)

2. Stateful keep track of every connection state and maintain state table. (Transport Layer 3rd Generation)

3. Proxy 2nd generation firewall, it had 2 types

3.1 application-level (layer 7 make decision on contents of packet) does not understand a certain protocol

3.2 circuit-level Proxy firewalls (session Layer) SOCKS is a circuit-level proxy gateway

4. Dynamic packet filtering 4th Generation firewall, once inside system decide to communicate firewall creates an ACL that allows the external entity to communicate with the internal system via this high port

5. Kernel proxy 5th generation FW uses stacking for packet inspection,.(Application Layer)

Three main FW architecture

• Screened host

• Dual-home

• Screened subnet

legal honeypot Enticement system indicating that free Songs are available to download on the honeypot system is entrapment, because this sets up the user to access the honeypot for reasons other than the intent to harm

DNS Hierarical structure 1992 the National Science Foundation (NSF)

authoritative root DNS server contained 13 files one for each root server.

DNS namespaces are split up administratively into zones and record are called Resource Record

It is recomended to have two DNS servers Primary and secondary and zones are shared via zone transfer.

cyber squatters, individualswho register prominent or established names, hoping to sell these later

Protocol field values TCP 6, UDP 17, ICMP 1, IGMP 2

Diverse routing is a method of providing telecommunication continuity that involves routing traffic through split or duplicate cable facilities. Alternative routing is accomplished via alternative media such as copper cable or wire optics

Transport layer is responsible for reliable data delivery , Congestion Control

IEEE 802.5 standard defines the token ring media access method.

802.3 refers to Ethernet's CSMA/CD,

802.11 refers to wireless communications and

802.2 refers to the logical link control.

NFS allow Different types of file systems to interoperate.

FRDS+ (Failure Resistant Disk System Plus).

The physical layer (layer 1) defines the X.24, V.35, X.21 and HSSI standard interfaces.

Circuit level proxy (Session Layer) does not anayze the application content of the packet in making its decisions, it has lower overhead than an application level proxy

Internet Message Access Protocol, version 4 (IMAP4) as an Internet protocol by which a client workstation can dynamically access a mailbox on a server host to manipulate and retrieve mail messages that the server has received and is holding for the client. IMAP4 has mechanisms for optionally authenticating a client to a server and providing other security services

TLS = (TLS) Handshake Protocol + TLS Record Protocol

Digital Signal level 1 (DS-1) is the framing specification used for transmitting digital signals at 1.544 Mbps on a T1 facility. DS-0 is the framing specification used in transmitting digital signals over a single 64 Kbps channel over a T1 facility. DS-3 is the framing specification used for transmitting digital signals at 44.736 Mbps on a T3 facility.

The Point-to-Point Protocol (PPP) was designed to support multiple network types over the same serial link SLIP only support IP over serial network

A Failure Resistant Disk System provides the ability to reconstruct the contents of a failed disk onto a replacement disk and provides the added protection against data loss due to the failure of many hardware parts of the server.

Data Link layer of the OSI/ISO model provides SLIP, CSLIP and PPP protocol.

DOD Application Layer contains protocols that implement user-level functions, such as mail delivery, file transfer and remote login.

DOD Host-to-Host Layer handles connection rendez vous, flow control, retransmission of lost data, and other generic data flow management between hosts. The mutually exclusive TCP and UDP protocols are this layer's most important members.

DOD Internet Layer is responsible for delivering data across a series of different physical networks that interconnect a source and destination machine. Routing protocols are most closely associated with this layer, as is the IP Protocol, the Internet's fundamental protocol.

DOD Network Access Layer is responsible for delivering data over the particular hardware media in use. Different protocols are selected from this layer, depending on the type of physical network

A differential backup is a partial backup that copies a selected file to tape only if the archive bit for that file is turned on, indicating that it has changed since the last full backup. A differential backup leaves the archive bits unchanged on the files it copies.

A full copy backup (which Microsoft calls a copy backup) is identical to a full backup except for the last step. The full backup finishes by turning off the archive bit on all files that have been backed up. The full copy backup instead leaves the archive bits unchanged.

Structured Query Language (SQL), implemented at the session layer (layer 5)

The Secure Electronic Transaction (SET) protocol requires two pair of asymmetric keys and two digital certificates.(Application Layer)

Hierarchical Storage Management (HSM) is commonly employed in very large data retrieval systems

Write-once, read-many (WORM) optical disk "jukeboxes" are used for archiving data that does not change.

Secure HTTP (S-HTTP) is designed to send individual messages securely. SSL is designed to establish a secure connection between two computers. SET was originated by VISA and MasterCard as an Internet credit card protocol using digital signature

Secure HTTP (S-HTTP), which operates at the application layer. S-HTTP is being overtaken by SSL and TLS works on transport layer#

X.400 is used in e-mail as a message handling protocol. X.500 is used in directory services. X.509 is used in digital certificates and X.800 is used a network security standard

An open network architecture is one that no vendor owns

intranet, a “private” network that uses Internet technologies.

extranet extends outside the bounds of the company’s network to enable two or more companies.

MAN Connects LAN, MANs are Synchronous Optical Networks (SONETs) or FDDI rings

SONET self HEaling network

ATM encapsulates data in fixed cells 53 bytes

T3 = 28 T1

T2 = 4 T1

T4 = 168 T1

T1 1.544 Mbps

T3 44.736 Mbps

OC1 51.84 Mbps

Statistical time-division multiplexing (STDM) determines in real time how much time each device should be allocated for data transmission

Frequency division Multiplexing: in available wireless spectrum Each frequency within the spectrum is used as a channel to move data

CSU/DSU provides a digital interface for Data Terminal Equipment (DTE), such as terminals, multiplexers, or routers, and an interface to the Data Circuit-Terminating Equipment (DCE) device,

circuit Switching Dedicated virtual link.

Packet Switching one connection can pass through a number of different individual devices.X.25 , framerelay

DTE is usually a customer-owned device

DCE is the service provider’s device

Switched Multimegabit Data Service (SMDS) is a high-speed packetswitched technology

Synchronous Data Link Control (SDLC) Dedicated leased lines IBM 1970

High-level Data Link Control (HDLC) protocol is also a bit-oriented link layer protocol used for transmission over synchronous lines (time based)

HDLC is extention of SDLC

High-Speed Serial Interface (HSSI) is an interface used to connect multiplexers and

routers to high-speed communications services

SIP is an application layer protocol that can work over TCP or UDP

isochronous network contains the necessary protocols and devices that guarantee continuous bandwidth without interruption.

voice stream is carried on media protocols such as the Real-time Transport Protocol (RTP).

User Agent Client (UAC) IPhone, SIP Phone

User Agent Server (UAS) SIP Server

New spam for VOIP = SPIT (Spam over Internet Telephony).

WEP only provide system authentication however 802.1X provides User authentication.

supplicant (wireless device),

authenticator (AP),

Authentication server (usually a RADIUS server).

EAP allows for mutual authentication to take place between the authentication server and wireless device and provide flexibility.

802.11i does not specify particular authentication protocols Cisco uses a purely password-based authentication framework called Lightweight Extensible Authentication Protocol (LEAP). Other vendors, including Microsoft, use EAP and Transport Layer Security (EAP-TLS), which carries out authentication through digital certificates. And yet another choice is Protective EAP (PEAP), where only the server uses a digital certificate

WEP Problems

1. static WEP encryption keys on all devices (every one have same pasword in company)

2. how initialization vectors (IVs) + RC4 are used that are XOR with packet to produce cipher text (IV value is used over and over again)

3. integrity assurance issue ICV Integrity check value

802.15 Bluetooth 1 to 3 Mbps 2.4 GHz Bluejacking is a type of attach some one send message to avoid setup ur blouetooth device undiscoverable.range is 10 Meter

For WAP transport layer security protocol called Wireless Transport Layer Security (WTLS) When WTLS data come for Internet service provider have to decrypt and encrypt it back in TLS And SSL so it is in plain taxt for a second whihc is called gap in the WAP

WAP uses an XML-compliant Wireless Markup Language (WML

Imode is same as WAP but target entertainment market , i-Mode works with a slimmed-down version of HTML called compact HTML

“log scrubbers” that remove traces of the attacker’s activities from the system logs

First generation firewall" packet filtering firewalls

"Second generation firewall" Proxy based firewalls. Under proxy based firewall you have Application Level Proxy and also the Circuit-level proxy firewall. The application level proxy is very smart and understand the inner structure of the protocol itself. The Circuit-Level Proxy is a generic proxy that allow you to proxy protocols for which you do not have an Application Level Proxy. This is better than allowing a direct connection to the net. Today a great example of this would be the SOCKS protocol.

"Third generation firewall" Stateful Inspection firewall. This type of firewall makes use of a state table to maintain the context of connections being established.

"Fourth generation firewall" dynamic packet filtering firewall

WAP Stack

Wireless Markup Language (WML)

Wireless Application Environment (WAE)

Wireless Transport Layer Security Protocol (WTLS)

Wireless Application Environment (WAE)

Wireless Session Layer (WSL)

Wireless Transport Layer (WTL)

TCP Wrapper is a program that monitors incomming packets. It is considered open source. TCP Wrappers can be used to control when UDP servers start, but it has no other control over the server once it is started. UDP servers may continue to run after they've finished processing a legitimate request.

Again PPTP operates at Layer 2 of the OSI model.

High-rate Digital Subscriber Line (HDSL) delivers 1.544 Mbps of bandwidth each way over two copper twisted pairs.

SDSL also delivers 1.544 Mbps but over a single copper twisted pair.

IPSec Transport mode is established when the enpoint is a host

10Base2, also known as RG58, or thinnet, is limited to 185 meters. 10Base5, also known as RG8/RG11 or thicknet, is limited to 500 meters

Failure Resistand Disk System (FRDS) is that it enables the continuous monitoring of these parts and the alerting of their failure.

AH (51) provides integrity, authentication, and non-repudiation. Security Associations (SAs) can be combined into bundles to provide authentication, confidentialility and layered communication.

The Well Known Ports are those from 0 through 1023.

The Registered Ports are those from 1024 through 49151.

The Dynamic and/or Private Ports are those from 49152 through 65535.

There are six basic security services defined by the OSI:

Authentication, access control, data confidentiality, data integrity, nonrepudiation and logging and monitoring.

POP 110

Post Office Protocol (POP2) 109

Network News Transfer Protocol 119

NetBIOS 139

The TRANSPORT LAYER establish logical connection between the END POINTS of an internetwork, that is, the originating host and the destination host.

The Land attack involves the perpetrator sending spoofed packet(s) with the SYN flag set to the victim's machine on any open port that is listening

The Boink attack, involves the perpetrator sending corrupt UDP packets to the host. It however allows the attacker to attack multiple ports where Bonk was mainly directed to port 53 (DNS