Fichas
Sin título
Fichas del conjunto (172)
- 1A Network can support more devices than the number of IP addresses that is has as long...As not all devices connect at the same time.
- 2How does DHCP work?DCHP server is configured to pass out IP addresses
Scope = Range
Subnet each mask for scope
Default gateway for scope - 3DHC ScopeIs a pool of IP addresses that a DHCP server may allocate to clients
- 4When DHCP boots up it broadcasts a...DHCP discovery packet
- 5After receiving the DHCP discovery packet...DHCP clients respond with a DHCP request
(add) - 6Time that a client holds an IP address is called theLease Time
Set by network admins
lease tiems can very for different types of clients such as wired and wireless
long means stable
short means high ip reuse - 7Problems with DHCPDHCP client tries to get a DHCP address and fails
- 8Symptoms of DHCP problemsOS will post an error
DHCP client will have a strange but special address in the network id
Can access local computers but cannot connect to the internet - 9Automatic Private IP Addressing APIPAAllows computer on the same lan to communicate
use available tool to see ip settings - 10The internet is made up ofNetworks connected by routers
- 11All routers connect to at leasttwo routers.
Therefore all routers have a minimum of two ports/ - 12Home routersConnect PC to DSL receiver or cable modem.
LAN side may connect
internally to a built-in
switch - 13a router is part ofall the networks it connects to
- 14Routers do two thingsForward an IP packed using the destination address in the IP header and a table in the router (Called forwarding)
2. Keep the table up to date by exchanging information with other routers (called routing) - 15Routers are computersAlmost any computer can be setup to be a router
- 16Routers may also be calledLayer 3 switches
- 17GatewayIs the rotuer or the ip address of the interface on the rotuer that connects to your local lan.
- 18Sequence of eventsSource sends packet to a router
Packet send router to router through internet
packet finally sent to rotuer connected to the destination network - 19Forwarding DirectFrom a router to a host on the same phusical network
- 20Forwarding Indirectfrom a router to another router
- 21When a router recieves a datagram itExtracts the network id from the destination ip in the datagram
uses table of possible destination net ids to determin which neighboring router to send it to
forwards the dataram to best neighboring router option - 22Every node on the network has arouting table
- 23destiation LAN IPThe IP address of a possible destination network
- 24subnet maskexpressed a dotted decoma; rather than that slash but same function
- 25gatewaywhere to send packet if network destination matches
- 26Interfacewhich port t send it out
- 27Metricdistance to destination. Lower is better
- 28Original sorce and destination Ip addresses are never changed by a routerk
- 29You can add orts to most serious routersyes
- 30Cicsco rotuers come withremovable modules
- 31A Public IP addresses isglobally inique and will be rotied through the internet
- 32a private ip is only validon a local network
- 33nat rotuertranslated private ro pblic ip addreses and vice versa
- 34Network Address TranslationAdding ports to the mix
A single public IP address shared by a number f computers - 35NAT enablesrouters to hide ip adddresses of computer on a lan from outside networks
- 36NAT conservesIP addresses
- 37Destination PortFixed predetermined number
Defines the function or session type
Most common range 0-1023 - 38Ephemeral portAn arbitrary number generated by sending computer
recieving computer uses this as a destination addresss - 39Certain computers such as webserversneed to be placed outside NAT
- 40Port ForwardingHides a port number from the internet
- 41NAT pros someConserves IP addresses
Easy to expand
Increased security - 42NAT cons someEach address translation requires changing IP header and recalculating the checksum which reduces performance
- 43Routers ForwardingForward an ip packet to the next hop using the destination adress in the ip header and a table int he rotuer
- 44Each host has a mini routing table that contains the ip of the network gateway rotuer and the loop back address along with a few other addressesnada
- 45As a network grows in size it becomes impossible to___________
- 46Each Autonomous system consists ofA set of rotuers and communicators
- 47Autonoous systems containInterior and border routers
- 48Interior rotuerscommuncae only with other interior rotuers in their autonomous system
- 49Border routersconenct each AS to other AS's
- 50Only Border or Interior rotuers exchange information with other Autonomous systems?Border
- 51Hop count diectly connected network is0
- 52Hop count to a netowrk reachable through one other rotuer is1
- 53Each rotuer table etry holds destination networknada
- 54Distance vector routing protocols someRouter transgers entire routing table to other routers in the WAN
(slides have nre) - 55Basic Router configurationMust have at least two connections
Must properly cofigure every port on a rotuer to talk to conencted network IDs
Make sure the routing table sends packets to where you want them to go - 56IP Version 5 was skipped becauseOf a series of mistakes
- 57IPv6 featuresConnectionless delivery
Variable size diagram
Concepts of most Ipv4 options - 58IPv6 changesLArger addresses upt o 128 bits
fixed size base header
more efficient rouing
better security and mobility - 59Linked ListA way to tag a list of things together by pointing to them.
- 60Only one set of colonrs allowed!::
- 612340:0:0:0:0:119A:A001:0 simplify!2340::1191:A001:0
- 62Show original form! 123::1:1123:0:0:0:.....fix
- 63EUI-64Extended unique identifier
64 bit - 64UnicastPne source one destination
- 65MulticastOne soruce many destinations
- 66AnycastOne soruce, closest member of a group
- 67AggregationRefer to slides for picure
- 68VERSVersion of the IP protocol used to create this datagram
- 69Flow LabelA flow is a path through the inernet along which intermediate rotuers guarantee a specific quality of service
- 70payload lenghnumber of bytes in datagram excluding base header
- 71Next headerType of info in the enxt section of the datagram
- 72Hop HOp optiionsoptions to be used only by routers
- 73An IPv6 datagram contains one20 byte extension header and a payload length of 1000 bytes
- 74An ipv6 datagram containsno extension headers
- 75No fragmentation by rotuers.
- 76IPsecProvide security on every ip packet
- 77Advantage of NATIS that it obscured the network organization
- 78IP addresses assaignment is handled by routers inIPv6
- 79What is not ready for ipv6?Most home rotuers
Some internet rotuers - 80What is ready for ipv6Most recent oeprating systems
All root dns servers
All tier one isp rotuers - 81Tunnels can b trickySo foten buy service a tunnel brooker to set them up and provide the fa end point
- 82ResolversAre cliets which resolve domain names
- 83Recursive ResolutionThe local name server contracts other name servers for resolution
- 84ITerative ResolutionLocal name server returns the name of another name server that the client should contact
- 85Caches ar soft stateThey may not alwys be acurate
- 86When TTL expriesCache is no longer valid
- 87Dns name serverruning DNS software
- 88NS zoneA container for a single DNS domain that gets populated with records
- 89DNS recorda line in the zone data that maps an FQDN to an i.p address
- 90Each DNS dmain has at leastone name server hat is the ultimate authority for that domain
- 91Root serverKnow the addresses of all the top level domain servers
- 92Authoratitive servershas the correct mapping for all hosts in its domain
- 93DNS ZonesAre databases in DNS servers that store the information
- 94Forward Lookup ZonesResolve names to IP addresses
- 95Reverse LOokup zonesResolve IP addresses to names
- 96Record "A"Records ath a host name to ipv4 address
- 97Record "CNAME"Records amtch a fully wualified domain name with an alias
- 98Record "MX"Records are sued for email address
- 99Record "AAAA"Records match a hsot name to an IPV6 address
- 100Appication programs fall into 2 caragoriesPrivate communication
Standardized service - 101Private aplicationLayer prorams are created by a programmer for private use
- 102Data representationIn this case the conteent and structure of web pae is governed by the HTML
- 103Data transgerIs governeed by HTTP
- 104HTTP isStateless
- 105State info such as login, password etc is stored in acookie
- 106A cookie is aColelction of information about the user
- 107Apace server runs onunix windows and linux
- 108HTTP is not a secure protocolits not srsly
- 109HTTPS is used whencredit cards and secure thigns are usedi
- 110Telnetis a terminal emlation program that enables you to connect to a sever and run commands
- 111One way to guarantee rivacy iswith a completely isoloated private network
- 112Isolated Private NetowkrsCannot go onto the itnernet
- 113Oriiginal IP datagram including header is encruptedParevents an Attackor from seeing who is sending how many packets to who.
This is caled Traffic analysis - 114Point to point tunnelingMost widely developed tunneling protocl
- 115VPN prosPRivacy at a low cost
Scalable solution - 116VPN consSecure network availabiity depends on internet availability
Less efficient
compelx to managa - 117In a local area networkSwitches are used t connect hosts together
- 118A VLANSvvatteered users are logically groped together
layes 2 and 3
more secure - 119A VLAN swotch can be prgrammedto sperate hsots into two logical LANS
- 120Each logical LANis its own broadcast domain
- 121Two ways todetermin which hsots is on which VLAN...
- 122VLAN proreduces trafic
easier to isolate provlms - 123vlans consneed more powerful switch
- 124Subnets act atLayer 3
- 125Vlans act atLayer 2
- 126DNS load balancig isthe oldest and most common method
- 127Each server has its ownip address
- 128Another approach to load balancing is touse a multilayer swith or context switch
- 129QOSControls badnwitch use
- 130Traffic shappingBandwidth managent
controls flow of packets in or otu - 131Intrustion detection systeminspects incoming packets
netowrk based ids
host based ids
rpeorting - 132intrusitn protctionadds capability to react to attacks
can back incoming backets on the fly - 133What is a goal of router?forward packets
maintain table - 134Port mirroringMirrors data from ports
- 135Proxy Server between clients and external serversIntercepts requests from clients
makes requests itself on behalf of clients - 136Port AuthenticationAuthentication at point of connection
Critical for AAA authentication - 137Encryptionscramble data
- 138Nonrepudiationguarantees data is as originally sent
- 139AuthenticationGuarantees daa is as originally sent
- 140Plaintexteasily read
- 141hashingone way function
oce plaintext has been ahsed it cannot be recovered - 142Digital Signuturesused for mseeage authentication
how u no they really are whot hey say they are? - 143Ceetification authroity acts asroot
- 144PGPpretty good privacy
- 145PGPpriamirly for email
- 146Digital Certificates and Asymmetric cryptology areclosely linekdd
- 147Digital Certificates used almost always tpverify echange of public keys
- 148Mandatory Access ControlSecurity level of each resource defined
- 149Discretionary Access controlOwnder of a resouce can permit address
- 150Role based accesss controlAccess based on user's role
- 151Limitations of PPPMultiple entry ppoint
Authenticator at endpoint may not have all the info
no modem banks
beyond endpoints data vulnerable - 152AAA Authentication Authorization AccountingAuthntication
connecting computer must provide credntials
Authorization
Defines allowed actions after authentication
Accounting
Logs authentication and actions - 153SocketIs the interface etweem the applciaton layer and the transport layer in the host
- 154Digital SignitureEncryption
Nonrepdudiation
Audhorization
Authorizatiom - 155Point to Point ProtocolEnables two point to point devices to connect
Authenticates with username and password - 156PPP limitationsMay have multiple points of entry
Authenticator endpoint may not have all authentication information - 157Most common types of Authentication serversRadius
Kerberos
Tacacs
LDAP - 158MD5is a type of hash
- 159802.1xPreexisting wireless authentication standard
- 160An altenrative way to provice application layer security is tobuild security into sockets
- 161Network Layer provides security usingIPSEC
- 162IPSEC was developed forIPv6 but usable in 4
- 163Transport mode encrypts onlythe data portin but leaves header unencrypted
- 164Mandatory Access ControlSecurity level of each resoruce defined
- 165Discretionary Access ControlOwnder of a resoruce can permit access
- 166Role based access controlaccess based on user's role
- 167What type of threats are there?System crashes
Access control weakness
Malware
Social Engineering
Denial of Serivces attack
Pysical intrusion - 168Social EngineeringCon games that have gone high tech
Manipulating people to gain access to a network
Telephone Scam - 169SwitchesCompatibility with neetwork architecture
Vlan and POE features - 170VLANsSegregate particular users computers or networks on their own VLAN
- 171Network MaangementServers on own VLAN
Light out management - 172xternal connections affected byrotuer
isp selection
Información
- Descripción
- Fichas sobre Sin título, creado por aznboy784 el 24/10/2014.
- Creado por
- aznboy784
- Visitas
- 7
- Valoración