New User Special Price Expires in

Let's log you in.

Sign in with Facebook


Don't have a StudySoup account? Create one here!


Create a StudySoup account

Be part of our community, it's free to join!

Sign up with Facebook


Create your account
By creating an account you agree to StudySoup's terms and conditions and privacy policy

Already have a StudySoup account? Login here

Topics Computer Science

by: Lowell Harris

Topics Computer Science COSC 6397

Marketplace > University of Houston > Chemistry > COSC 6397 > Topics Computer Science
Lowell Harris
GPA 3.94

Rong Zheng

Almost Ready


These notes were just uploaded, and will be ready to view shortly.

Purchase these notes here, or revisit this page.

Either way, we'll remind you when they're ready :)

Preview These Notes for FREE

Get a free preview of these Notes, just enter your email below.

Unlock Preview
Unlock Preview

Preview these materials now for free

Why put in your email? Get access to more of this material and other relevant free materials for your school

View Preview

About this Document

Rong Zheng
Class Notes
25 ?




Popular in Course

Popular in Chemistry

This 83 page Class Notes was uploaded by Lowell Harris on Saturday September 19, 2015. The Class Notes belongs to COSC 6397 at University of Houston taught by Rong Zheng in Fall. Since its upload, it has received 79 views. For similar materials see /class/208164/cosc-6397-university-of-houston in Chemistry at University of Houston.


Reviews for Topics Computer Science


Report this Material


What is Karma?


Karma is the currency of StudySoup.

You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!

Date Created: 09/19/15
Mobile Services amp Applications 70 1 Distributed Systems I A distributed system is a collection of autonomous programmable failureprone entities that are able to communicate through a communication medium that is unreliable ii Goal sharing of resources computational storage I Example of distributed systems 71 lIll Gnutella peer to peer system A Sensor Network F00d WCb Of Little Rock Lake WI 72 Key challenges Heterogeneity of its components Openness allows components to be added or replaced Security Scalability Dependability Concurrency of components with resource sharing as part of the goal I Transparency 73 39 e 111 Q Service Layers in D8 Applications senices Middleware Operating system Platform Computer and network hardware 74 l I L39 Architectural Models of DS I Based on the division of responsibility and the placement of the components among different entities I Clientserver model 39nvocation 39 39 i V invocation M VVq result 33 result Key Process 0 Computer 75 pl JCIient server ModeT Key Process 0 Computer 76 Proxy Server and Caches LJ 77 39I II U Peer Processes 78 U Mobile Code I Code that can be sent from one computerto another and run at the destination El Ex Java Applet Cl Better interactive response and reduced communication overhead El Push possible a client request results in the downloading of applet code Mobile Agent I A running program including both code and data that travels from one CO mputerto another in a network by itself Cl Pl l V lTy L4 l i Interact with local resources Migrates its execution and data state across multiple computers pes An information agent searches for information residing on remote nodes and reports back to the source eg crawler A computation agent seeks underutilized network resources to perform CPUintensive processing functions eg worm program 39 A communication agent couriers messages back and forth between clients residing on various network nodes mobile Node N Iquot A r Incoming Agcnlllost Agems Outgoing I agent mobile agent 00 80 Why are Mobile Agents useful Traditional clientserver approach search engine web server Mobile Agents and Active Networks FritzHoha39informatikunistuttqartde Smartnet 99 81 Why are Mobile Agents useful Traditional clientserver approach search englne web server 82 II Why are Mobile Agents useful Traditional clientserver approach web server search engine web server 83 Why are Mobile Agents useful Traditional clientserver approach web server 84 l quot Why are Mobile Agents useful I In the traditional clientserver approach does not scale even for today s VWWV size extensive network usage I Bottlenecks Cl network bandwidth 1 processing capacity of search engine 85 quot1 Why are Mobile Agents useful mobile agent approach search engine web server 86 quot1 Why are Mobile Agents useful mobile agent approach search engine web server 87 i Why are Mobile Agents useful mobile agent approach migration search engine web server 88 i Why are Mobile Agents useful mobile agent approach search engine web server 89 i Why are Mobile Agents useful mobile agent approach search englne web server 90 1 Why are Mobile Agents useful mobile agent approach migrations search engine web server 91 hin Client I A software layer that supports a windowbased user interface to execute remote applications ii X 11 i VNC 92 Mobile Computing I In broad sense it is associated with mobility of hardware data and software in computer applications El Mobility of hardware change of location of devices Location database I Resource discovery El Mobility of data El Mobility of software Mobile code process migration mobile agent 93 L New Challenges Heterogeneity of its components Openness allows components to be added or replaced Security Scalability Dependability Concurrency of components with resource sharing as part of the goal Transparency Location is dynamically changing information Cost of communication is asymmetric Severe power restrictions on mobile hosts Limited storage available Volatility of information increases with the change of location Frequent and foreseeable disconnections Security issues due to mobility of hosts 94 Ill Two Extremes Autonomy Interdependency Adaptability I Adapt to mobility available resource connectivity etc 95 39 ill I Mobile Computing Environment Mobile GSM connection Mbps to HGbps Home Base Node V reless LAN Cellular Data 96 0080 6397 Wireless Networking and Mobile Computing Dr Rong Zheng rzhengcsuhedu Mobile computing 7 Wireless networking I Mobile computing computing on the move can be wired I Wireless networking facilitates mobile computing with flexibility of movement 39 1 U Mobile Computing Models Iquot I Nomadic 1 With wired network connectivity at access points 13 May be disconnected when move I Infrastructual i Cellular networks Ci V reless LAN connected to the Internet I lnfrastructureless i l Peertopeer network El Mobile ad hoc networksl 39 a L Advantages of using wireless I Free of wiring 1 Low cost ll Ad hoc deployment possible Mobility 1 Computing communication anywhere 39 I Lquot LimitationsChallenges in using wireless Relatively low data rate Availabilityvariation of Channel qualityinterference Security Burn up your brain 39 I Name a Few Wireless Communication Systems I Public radio satellite GPS Cellular phone gate opener pager wireless LAN bluetooth earphone cordless phone walkie talkie wireless sensors Remote control History of Wireless Communication Systems 1942 1983 1997 Hedy Lamarr AMPS IEEE 80211 invented frequency introduced standardized Hopping 1901 60 70 1993 1994 Marconi s Cellular Concept lS95 CDMA transatlantic from Bell Labs wireless GSM telegraph 1994 Bluetooth I Moore s law the number oftransistors on a microprocessor would double approximately every 18 months Evolution of Cellular Systems Analog Cellular quotJ cdma20001XR39I39I39 cdma20001xEV DV D0 SGPPZ cdma20003xRTT Evolution of Wireless Networks WMAN 80216 Freq of Raw Data Modulation Range Channel Rate WLAN 80211a 5GHz 12 54Mbps OFDM 60 ft 80211b 24GHz 3 11Mbps DSSS 300 ft 80211g 24GHz 3 54Mbps OFDM 150139t 75Mbps 31 miles Put Things in Context Wireless Grid WP SiTl quot Harm Inmmpenhlll W Gunman EMA J r the M V Annomit 39 v I x V nmrk quot quot 39 Madam 7 r r 2 55H 39 werl ma Scope of this course I Focus packet radio networks I Personal Area Networks Sensor Networks I I Mobile ServiceApp Medium Access Control Physical Layer Munoes luewe euew nonuoo Jemod SOC TCP in MANET I Results from Analysis of TCP Performance over Mobile Ad Hoc Networks by Gavin Holland and Nitin Vaidya Mobicom 99 111 l39hmughput IIKIJpS 1000 500 H H 39 quotA quotquot AAA 1 2 4 6 8 10 Number of Hops Static Topology Hops 771 m ughput Hops 13529 2 6 l 3 4451 4 2593 5 IS I 0 i 348 7 I50 8 141 9 I39 l0 I392 Backof envelop Comiputation Delaybandwidth product L Mobile Scenario t 4 s a 2 m 8 m C 5 3 9 E e I 39C 8 CO 9 53 l s I a g a S Inquot D l 1 z39 E a E EC 039 SCIE 39JIJJ Expech Throughput qma Expand Through 5pr Speed 2ms Speed 10ms 3 3 C C O E o 13 3 3 9 9 C a C I I u g 8 o h 39C ICI S a an E quot a 3 Q n g D a I 1 a i D E r f 2 51 133 5c 3 Etyecnedl39hnughpuu xbyz Em ud39 xmxshpu 511111 Speed 20ms Speed 30ms 24 I L39 Affects on TCP Performance lll in Hops DIVgt003 00 01 02 03 04 05 06 O 08 09 10 Time Normalized nod 10quot CC C D I 1 x y I x O 100 200 300 Time seconds xunxxvnxluuxuun l Packer Sam E I l x I y I x f I v V w v PacketRecv g 5060 6 0 Ac Recv E I X Packet Dropped 5 fl 0 4 o Time seconds I Explicit Link Failure Notification ELFN I Goal provides the TCP sender with information about link amp route failures I Signaling mechanism l host unreachable ICMP message or 1 Piggybacked on the route failure message I TCP s reaction l Upon reception of ELFN TCP disables its retransmission timers and enters standby mode m In standby send periodical probes to see ifa route is reestablished ill L39APerformance with ELFN IDJE 2 110 E 2 2 i g 2 5 E ED i r r I I quot I I in wt sn 1m Experth Thrmghpm maps Erpemd Thmughput laps I1IIIIII 2 IIII39I M I 39Ilh gt n in um 15 13 SEE Eta 1mm 39 llruudll ll mum rnm l I mum I mun 5E0 1er 5 10 Expertid Throughput Hips Enema Throughput Kbps 243 III IIIvIIII lu39xj 1m my III IIIIIIII Wm 1IIIIIII Libpcap and Libnet Q Why Libnet amp Libpcap 0 Allow manipulation interception of link layer packets 0 Using socket programming kernel will fill in the source IP address checksum etc Raw socket is one way to write IP packets directly but not everything is in IP 0 Allow testing of new protocols prcap 0 charpcaplookupdevchar errbuf Oretu sapointer ane rkd C t eo se char errbufPCAPERRBUFSIZE dev pcaplookupdeverrbuf 0 pcap t pcap open livechar device int snapIen int promisc int toms char ebuf 0 to obtain a packet capture descriptor to look at packets on the network 0 snaplen maximum bytes to capture 0 promisc Whether set to promiscuous mode 0 toms timeout 0 ebuf error message hbpcap int pcapdatalink pcapt p 0 Returns the link layer of an adapter 0 DLTEN10MB Ethernet lOMb 100Mb 1000Mb and up 39IDKTPPP 0 LHZSLJP Libpcap int pcap compilepcap t p struct bpf progEam fp char str int optimize bpfuint32 netmask to compile the string str into a filter program 1 upon error int pcapsetfilterpcapt p struct bpfprogram fp to specify a filter program fp is a pointer to a bpfprogram struct usually the result of a call to pcapcom pile 1 upon failure Filter Expression Filter expression consists of an id preceded by one or more qualifier 0 Type host net and port o Eg net 128339 port 2039 0 Dir direction of transfer 0 srC dst srC or dst srC and dst 0 Proto ip th arp 0 tcp dst port ftp data 0 eXpr relop eXpr relop relational operations gt lt gt2 lt2 I 0 proto expr size expr gives the offset size gives the length of data o ip62 amp Oxlfff 0 th13amp 3 l 0 usersaInnuuuumvuumn Source For Deatlnatlun Fun Sequence Number Acknowledgement Number u A p n x r HLEN Reserved R a s s v x WmdUW s x x Y n u Checksum i Urgenl Puimer Options fany Padding Dela IP Header 15 1F 31 439th Hm header xrhn ype ufservim V wrsmn lmgm J as 16 nu mml lengm 1n hyles Hm mmu cannn m nagmem nrrset mm pmmml Hi hiI header rherksum 20 bytes K39bxt time D IN 1 1L 3271311 source JP address 324m destinalmn 1P address nnunns nr anv prcap uchar pcapnextpcapt p struct pcappkthdr h reads the next packet and returns a uchar pointer to the data in that packet 1nt pcaplooppcapt p 1nt cnt pcaphandler callback uchar user keeps reading packets until cnt packets are processed or an error occurs callback a Iunctlon handler user optional arguments References 0 Unix Network Prool39alnnminO Vol 1 0 http WWW caidaorg outreach resources 0 http wwwcetnauedumc8SocketTutorialssection 1 html What is Iibnet 0 A C Programming library for packet construction and injection 0 The Yin to the Yang oflihpcap 0 Libnet s Primary Role in Life 0 A simple interface for Packet construction and injection 0 Lihnet 15 good for 0 Tools requiring meticulous control over every eld of every header of every Packet 0 Lihnet 15 not well suited for 0 Builciing clientrserver Programs Where the operating system should he doing most of the Work 9 What s inside of libnet 0 As oflibnet 112 0 About 18000 lines of C source code 0 109 exported functions 67 packet builder functions 0 Portable to all of today s hottest operating systems Windows OS X BSD Linux Solaris HPUX Why use Iibnet Portability LIDHCI IS Portable 0 all OI Our IaVOI lte and exqulsltely Cnerlsned Operatlng Systems Ease of Use 0 As we Will see Libnet 1 1x exports a braindead simple interface to building and injectmg packets 4 easy steps Robustness 0 Libnet supports all of today s in demand protocols with more added all the time More than 30 supported in Libnet 112 see next slide Several link layers Ethernet7 Token Ring7 FDDI7 8021 planned Open Source 0 Licensing Libnet is released under a BSD license meaning it is basically free to use 0 Response time in bug fixes Large user base bugs are IIXCCI qulCKly llbnetilnlt llbnetibullditcg 39 llbnetiDulLdilpK4 llbnetibulldiethernet 11t 17 te llbnetidestr0y Q The libnet context i m SLKJEY hnpwlam 0 Opaque monolithic data structure that is returned from libnetinit o l 0 Maintains state for the entire session 0 Tracks all memory usage and Packet construction 0 Defines and describes a libnet session 0 Used in almost every function 0 More detail later 9 Packet construction 0 The core of Libnet s functionality Packets are built in Pieces 0 Each Protocol layer is usually a separate function c 1 Generally two 7 four function calls to build an entire packet 0 Packet builders take arguInents corresponding to header values 0 Approxilnates an IP stack must be called in order 0 From the highest on the 051 model to the lowest 0 A successful call to a builder function returns a Ptag Packet construction tcp libnetbuildtcp srcprt dstprt OXOlOlOlOl OX02020202 num THSYN 32767 0 0 LIBNETTCPH payloads payload payloads 1 0 source port destination port sequence number acknowledgement control flags window size checksum urgent pointer TCP packet size payload payload size context ptag Ptags and Pblocks aearmq a new pmmoc um a yew ma 5 rammed me an 9351va uroloml b ock an old may moaned 39 0 Protocol Tag ptag 0 Protocol Block Pblock 0 Protocol Tags ptags used to track Protocol Blocks pblocks 0 Whenever a new packet piece is built it is stored in a phloek and a new ptag is returned 0 Whenever an existing packet piece is modi ed an old ptag is used hooped Packet updating 0 Ptags are handled directli b the user pblocks are not Th r ace to append arbitrary payloads to packets MP 1P iider functions suA A ort this interface 39 Use is optional tap libnetibuilditcpl eneJne eeunee part aegnne destination art EIx lEIlEIlEIl sequence number nx znznznz acknowledgement H SYN cuntrnl ags 32767 Window 5122 n checksum n urgent painter numwmuui ye mu 1 Wire injection methods 0 Raw socket interface less complex 0 Mid level interface packets built at the IP layer and above No link header needs to be built 0 Removes all routing and interface decisions 0 Useful for legitimate packet tools that do not need to spoof address information 0 Packet passes through kernel s IP stack Routing checksums rewalls all an issue 0 Less than granular level of control next slide 0 Link layer interface more complex 0 Low level interface packets built at the link layer 0 Packet does not A ass throuuh the kernel s IP stack Sovereign control of every field of the packet All address and routing information needs to be provided Some operating systems stamp outgoing MAC address of the Ethernet header this is b A assable IP IP Total lP Max size Fragmentati Checksu lP ID lP Source before kernel Length on m complains Performed if Linux packet is Always Always Filled in if Filled in if 22 larger than filled in filled in left 0 left 0 1500 bytes MTU Performed if Solaris paCket 395 Always 2 6 larger than filled in 39 MTU Sets DF bit Performed if OpenB packet is Always SD 28 largerthan filled in MTU Packet Checksums 0 Programmer no longer has to worry about Checksum computation 0 Common usage programmer specifies a 0 libnet autocomputes 0 Can be toggled off to use Checksum of 0 0 Alternative usage programmer specifies value libnet uses that 0 Useful for fuzzing using pre computed Checksums 1p libnetibu1ldiipv4 LIBNETJPVALH LIBNETiTCPiH payloadis length O TOS 242 IP H O 1P frag 64 TTL IPPROTOiTCP protocol O checksum srciip source IP dStilp destination IP NULL payload O payload l Initialization libnett libnetinitint injectiontype char device char errbuf Initializes the libnet library and create the environment SUCCESS A libnet context suitable for use FAILURE NULL errbuf will contain the reason inj ectiontype LIBNETLINK LIBNETRAW4 device prO l92l680l NULL errbuf Error message if function fails l libnvcinitLIBNETLINK prO errbuf if 1 NULL fprintfstderr libnetinit s errbuf Device interface selection Happens during initialization libnet1nitLIBNETLINK prO errbuf 0 Will initialize libnet s link interface using the pr0 device libnetinit LIBNETLINK 192 168 O 1 errbuf 0 Will initialize libnet s link interface using the device with the IP address 1 92 16 8 O 1 1 ibnetini t LIBNETLINK NULL errbuf 0 Will initialize libnet s link interface using the first up device it can find 0 libnetgetdevice l 1 ibne tiI1i t LIBNETRAW4 NULL 0 Under the Raw socket interface n0 device is selected errbuf Exception Win32 does this internally since it is built on top ofWinpcap New devices with no IP address can be specified for use stealth Error handling char libnetgeterrorlibnett 1 Returns the last error message generated by libnet SUCCESS An error string NULL if none occurred FAILURE This function cannot fail 1 The libnet context pointer l libnetautobuildipv4len IPPROTOTCP dst 1 if 1 NULL fprintfstderr libnetautobuildipv4 s libnetgeterrorl Address resolution uint32t libnetname2addr4libnett 1 char hostname uint8t usename Converts a IPv4 presentation format hostname into a big endian ordered IP number SUCCESS An IP number suitable for use with ibnetbuid FAHJJRE LthhistechnmaHy 255255255255 1 The iibnet context pointer hostname The presentation format address usename LIBNETREOLVELIBNETDONTRESOLVE dst libnetname2addr4l argvoptind LIBNETDONTRESOLVE if dst 2 l fprintf stderr libnetname2addr4 s libnetgeterror 1 Address resolution char libnetaddr2name4uint32t address uint8t usename Converts a big endian ordered IPv4 address into a presentation torm at address SUCCESS A string of dots and decimals or a hostname FAILURE This function cannot fail address The IPv4 address US ename L I BNETREOLVE L I BNETDONTRE SOLVE printfquotS quot libvvmmdr2name4 i LIBNL DVTRESOLVE 1 uintl6t sum Packet construction UDP libnetptagt libnetbuildudpuintl6t sp uintl6t dp uintl6t len uint8t payload uint32t payloads libnett libnetptagt ptag Builds a UDP header SUCCESS A ptag referring to the UDP packet FAILURE l and libnetgeterror can tell you why sp The source UDP port dp The destination UDP port len Length of the UDP packet including payload sum Checksum 0 for Iibnet to autofill payload Optional payload payloads Payload size 1 The Iibnet context pointer ptag Protocol tag Packet construction IPv4 libnetptagt libnetbuildipv4uintl6t len uint8t tos uintl6t id uintl6t frag uint8t ttl uint8t prot uintl6t sum uint32t src uint32t dst uint8t payload uint3 gtt39 Davloadq 1ibntt39 1 libnet39 Di39aCfi39 39Di39aO39i Builds an IPv4 header SUCCESS A ptag referring to the IPv4 packet FAILURE gigand libnetgeterror can tell you len Length of the IPv4 packet including payload tos Type of service bits id IP identification frag Fragmentation bits ttl Time to live prot upper layer prOIOCOI sum Checksum 0 for Iibnet to autofill src Source IP address Packet construction IPv4 libnetptagt libnetbuildipv4uintl6t len uint8t tos uintl6t id u1ntlbt frag u1nt8t ttl u1ntat prot uintl6t sum uint32t src uint32t dst uint8t payload uint32t payloads libnett l libnetptagt ptag Builds an IPv4 header SUCCESS A ptag referring to the UDP packet FAILURE gigand libnetgeterror can tell you dst Destination IP address payload Optional payload payloads Pawoadske l The Iibnet context pointer ptag Protocol tag Packet construction Ethernet libnetptagt libnetbuildethernetuint8t dst uint8t src uintl6t type otmoc payload oint32t payloads libnett l libnetptagt ptag Builds an Ethernet header SUCCESS A ptag referring to the Ethernet frame FAILURE Qvtgland libnetgeterror can tell you dst Destination ethernet address src Source ethernet address type Upper layer protocol type payload Optional payload payloads Payload size 1 The libnet context pointer ptag Protocol tag Shutdown void libnetdestroylibnett 1 Shuts down the Iibnet environment l The Iibnet context pointer libnetdestroyl Libnet with other components GNIP A poor man s Ping A simple application 0 Simple ping client 0 250 lines of source 0 Illustrates some of libnet s and libpcap s core concepts 0 IPv4 packet construction 0 ICMP packet construction 0 Looped packet updating 0 Packet filtering capturing and dissection 11 1clude lt11bnethgt 11 1clude ltpcaphgt Lib a ackeTIilter pa pp 3 39 quot deflne GNIPiFILTER quot1cmpO 0quot same 1mm 3 Vold usagechar 1m ma1n1nt argc char argv llbl letit 1 NULL pcapit p NULL uilnt87t packet u 11391t32 t dst 17 src 17 uilntl67t 1d seq count mt c luterval O pcapifd tlmediout uilnt87t loop payload NULL U711 1C327t payload s O llbnetgptagit 1cmp 0 1p 0 char dev1ce NULL fdiset readiset struct pcapjkthdr pcihdr struct tlmeval tlmeout struct bpfjrogram filtericode bpfiuilnt32 localinet netmask struct llbnetilpvllihdr 1p7hdr struct llbnetilcmpvllihdr 1cmp7hdr char errbuf LIBNETiERRBUFisIZE Munmllhluwnlexl variables Side e ectulclused i terrace wh11ec getoptargc argv quotI1cquot EOF sw1tch c case 39I39 dev1ce optarg brea case 39139 luterval atol optarg count atol optarg c argc 7 optlnd 1f c canolarnw 55555 555 5555 15555y w 5 555555u5mm5 555555 555555 LIanPhAseDne 7 7 5 5 5 5 A5 1 quotmy 555555555555 555555 55555 5 5555555 555 nu5555555 gt 5 55m5 5 mm 5 55555 7 5555 1555upd5w555mm 5 55555 mm 5 5 5555555 555555555555 555515555555m 5515 gate 555 555555555 5555 w p 7 5555 55mv555vc5 255 u n 5555mm 5 mm 5 I y 5 555555555555 555555mv5n 55555 5 555555 9555 555 555mm 955 555 555555 5555 55 555 55555555 5 Smu nmw 5 55555555555I55m5 555555 5555555 555555 7 7 7 7 7 5 5 ucMP Ema may 555555555555 55554555555555 5 555555 5555 555 55555 555 555 5555 5555 5 5 555555555 55555555 5555555555 1 555555 5 555555555555 5555555U5 5 55555555555555 9 55 555 5551 555 5555 55 555 5555555 5 5 55555555555m 55555755555 71 5 555555555555 55555555555 5 55555555555I5m 9555 555 5555 5 5555555255555 555555555 unmasmm 5 5 5 51y 5 555755 5 555555555555 555 55555555n 55 5555555 5y5 55795555555 m y 155 9555 555 GmsomceP Srcilp llbnetigetilpaddr4l Eddesa if srciip 71 fprintfstderr quotCan39t determine source IP address Snquot libnetigeterror l goto bad interval interval interval l timeouttvisec interval timeouttv7usec O pcapifd pcapifilenop fprintfstderr quotGNIP s s d data bytesnquot libnetiaddr2name4 dstiip l libnetiaddr2name4 dstiip O LIBNET in4 H LIBNET ICMPV4 ECHO H payload S 7 Llhm Phase m umnhsnu 7 a Jump 1 for ma 7 getpld r seq 7 n Jump mamyr map Jametjuuagcmpchhut Icupjmo u u ad 59 Payload PayluauLs 1 tilstderr Can t mud map baa mneuzetenu 1 y y gum had rpm 1 m llbnetibulld71pvdl mamum anwmgmpvajcnoj 4 mrlntflstderr Can t mud 1p heaae llbnetigeterrur u w y gum had c llhnet quotmam f n 711 fpuntflstderr wme erru Rasm gum had mgmnmzzn 100p seqH payload 5119 thne 0mm tag der 245m r 245m llbnetigeterrur u y FDizEROampreadiset FDisETpcapifd ampreadiset Imarracs muhiplaxlrg for timediout O t1medout ampamp loop c selectpcap7fd l ampreadiset O O ampt1meout sw1tch c case r fprlhtfstderr quotselect shquot strerrorerrho goto a case 0 tlmediout l cohtlhue default 1f FDilSSETpcapifd ampreadiset m tlmediout l cohtlhue fall through to read the packet packet uilht87t pcapihextp amppc7hdr 1f packet LL cohtlhue quotIslhlsarcsponaa logic 39 1p7hdr struct libhetilpv47hdr packet 14 lampihdr struct llbhetilcmpv4ihdr packet 14 1p7hdrrgt1p7hl ltlt 2 1f 1p7hdr7gt1pisrcsiaddr dstilp cohtlhue 1f lampihdrigt1cmp71d 1d fprlhtfstderr quotd bytes from s 1cmpiseq9d ttl9dhquot htohs1p7hdrigt1pileh llbhetiaderHame41p7hdr7gt1pisrcsiaddr O 1cm hdr7gticm se 1 hdr7gt1 tt len tPnase Four p p q p p llbhetidestroyl pcapiclosep return EXITisUCCESS Al GNIP output rounderProjectsmisc root gnip 4222 GNIP vnsc baksysgtenet 222 28 data bytes 22 icmpseq0 ttl247 22 icmpseql ttl247 22 icmpseq2 ttl247 22 icmpseq3 ttl247 24 Lu111pbcq4 ttl247 28 bytes from 28 bytes from 28 bytes from ONION 28 bytes from 11515151515 l 2 8 bytes LrULLL quotC


Buy Material

Are you sure you want to buy this material for

25 Karma

Buy Material

BOOM! Enjoy Your Free Notes!

We've added these Notes to your profile, click here to view them now.


You're already Subscribed!

Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'

Why people love StudySoup

Jim McGreen Ohio University

"Knowing I can count on the Elite Notetaker in my class allows me to focus on what the professor is saying instead of just scribbling notes the whole time and falling behind."

Janice Dongeun University of Washington

"I used the money I made selling my notes & study guides to pay for spring break in Olympia, Washington...which was Sweet!"

Bentley McCaw University of Florida

"I was shooting for a perfect 4.0 GPA this semester. Having StudySoup as a study aid was critical to helping me achieve my goal...and I nailed it!"


"Their 'Elite Notetakers' are making over $1,200/month in sales by creating high quality content that helps their classmates in a time of need."

Become an Elite Notetaker and start selling your notes online!

Refund Policy


All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email


StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here:

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to

Satisfaction Guarantee: If you’re not satisfied with your subscription, you can contact us for further help. Contact must be made within 3 business days of your subscription purchase and your refund request will be subject for review.

Please Note: Refunds can never be provided more than 30 days after the initial purchase date regardless of your activity on the site.