The ACK and NACK of Programming

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1 NFJS Software Symposium Series 2012 The ACK and NACK of Programming Ken Sipe

About Speaker http://kensipe.blogspot.com/ http://del.icio.

com Developer: Embedded, C++, Java, Groovy, Grails, C#, Objective C Speaker:

2 About Speaker Developer: Embedded, C++, Java, Groovy, Grails, C#, Objective C Speaker: JavaOne 2009 Rock Star, NFJS, JAX Microsoft MCP Sun Certified Java 2 Architect Master of Scrums Agile Coach Instructor: VisiBroker CORBA Rational Rose, OOAD

3 How Well Do You Know Your Computer? 3

4 The network is the computer -- John Gage 4

5 Motivations n Understand One Abstraction Lower then where you are n Developer Productivity n Security

7 7

8 Agenda n Understanding the Challenges n OSI n Tools of the trade n WiFi

12 Networking is Hard n Asynchronous n Bandwidth n Latency n Service Discovery

13 OSI Model 13

14 7 Layers n Physical Layer n Data-Link Layer n Network Layer n Transport Layer n Session Layer n Presentation Layer n Application Layer

15 Layers n Each Layer Has a Header n contains protocol info Has a Body n data Wraps the Previous Layer n The body of a layer is the head + body of the previous layer

17 Socket TCP IP Ethernet Ports Hardware

18 Host to Host Point to Point

20 Physical Layer (Layer 1) n Cables n Physical Connections

21 == promiscuous mode cloaking

22 n Hub extends single LAN n Bridge / Layer-2 Switch connects 2 or more LANs together works a data link layer n Router / Layer-3 Switch connects any combination of LANs and WANs works at network layer

23 { Data Link Layer (Layer 2) n <inter-office mail> relative to postal system n Media Access Control (MAC) addresses globally unique address 6 bytes xx:xx:xx:xx:xx:xx 90:27:e4:f8:b5:15 27 e4 f8 b5 15 {90 vendor code interface serial number

24 MAC(s) n Ethernet Header 14 bytes source and destination MAC for this packet n MAC isn t intended to change fingerprint of the network

25 ARP n Address Resolution Protocol (ARP) associates MAC - IP broadcast n Hey... Who has IP X? n Resolution usually is cached

27 n arp tools arp n arp -a n arpon -l n arpon -i wlan0 -D n mac spoofing ifconfig wlan0 hw ether 00:80:48:BA:d1:30 n arp poisoning arpspoof n arpspoof -t <router_id> <local_ip> n arpspoof -t <local_ip> <router_id> ettercap -NaC <router_id> <local_ip>

29 Network Layer (Layer 3) n Internet Protocol (IP) n Protocols ICMP ARP RARP

30 IP n Internet Protocol (IP) versions: n Form: n IPv4 n IPv6 xx.xx.xx.xx or n Size: 20 bytes

31 n IPv4 32 bits n private

32 Datagrams Header

33 n IPv6 128 bits (16 bytes) n 2001:0db8:3241:0000:0000:9a8f:00c9:952e leading zeros not written consecutive all-zero groups can be replaced with :: n 2001:0db8:3241::9a8f:00c9:952e Reserved n ::1/128 ( in IPv4)

34 IP n IP alone does NOT guarantee: connections ensure delivery

37 DNS n Domain Name System resolve host name to IP address (A) resolve an IP address to host name (PTR) find mail servers for domain (MX) find name servers for domain (NS) find host name for IP (AAAA) alias (CNAME)

38 IP Tools n ifconfig / ipconfig n whois n ping n dhclient DNS utility n nslookup n dsniff - DNS Spoofing dnsspoof

39 Where in the IP? n traceroute n netstat -r n zenmap

40 Transport Layer (Layer 5) n Major Protocols Transmission Control Protocol (TCP) User Datagram Protocol (UDP) n TCP used by: HTTP SMTP FTP

41 UDP n Less overhead no connection establishment n more effiecient no guaranteed delivery n Data reception from more than one machine n apps weather, time, video, games

42 TCP n TCP Reliable Bi-Directional n Ensures packets are ordered prior to sending to the next layer TCP Flags sequence numbers

43 TCP header

44 TCP TCP Flag Meaning Purpose URG Urgent Important data ACK Acknowledgement Acks a packet PSH Push Do not buffer RST Reset Resets a connection SYN Synchronize Synchronizes the sequence numbers at the beginning of a connection FIN Finish Goodbye

46 TCP Tools n tcpdump n wireshark n Note: pcap - packet capture n libpcap n WinPcap

47 Wireshark n find top talkers on the net n recognize the most common connection problems n spot delays between client request n detect network congestion n graph application throughput n identify service response times

49 Session Layer n Ports 64k possible ports < 1024 privileged ports n Well Known (/etc/services) 22 - ssh 25 - smtp 80 - http https

50 Socket n Socket IP Port :80

51 Socket Tools n lsof lsof -i n open connections lsof -i -n n just TCP/UDP lsof -i :8080 n who owns 8080 lsof -u ksipe n what owned by ksipe lsof +p 6565 n what all does pid 6565 own

55 nmap n nmap -O localhost guess the OS n nmap -T4 -A localhost agressively scan, at a level 4 (O, sc, traceroute)

56 Session Tools - Proxy

57 Other useful tools n netcat $ nc -l 3333 $ nc n $ ssh -f -L 23333: :3333 me@ sleep 10; nc pv -b > backup.iso ssh with a port forward copy of file through nc port 3333 firewalled, port 22 open for ssh

58 Wifi 58

61 WiFi Almost impossible to secure 61

63 Management Frame n Auth n De-Auth n Association Req n Association Resp n Reassociation Req n Reassociation Resp n Beacon n Probe Request n Probe Resp

66 WEP Crack n In seconds to crack 104-bit WEP key 1.7GHz Pentium M < 1 min for data capture n Today with GPU fjr8n n CPU in 24 sec w/ 9.8 million guesses/sec n GPU < one sec w/ 3.3 billion guesses/sec fh0gh5h n CPU ~ 4 days n GPU ~ 17 mins 30 secs

67 Securing your WiFi Access n Business VPN n TorGuard n Tor Project

69 Summary n Top Tools WireShark nmap lsof netstat routetrace

70 Questions Please Fill Out Surveys

Layer 4: UDP, TCP, and others. based on Chapter 9 of CompTIA Network+ Exam Guide, 4th ed., Mike Meyers

Layer 4: UDP, TCP, and others. based on Chapter 9 of CompTIA Network+ Exam Guide, 4th ed., Mike Meyers Layer 4: UDP, TCP, and others based on Chapter 9 of CompTIA Network+ Exam Guide, 4th ed., Mike Meyers Concepts application set transport set High-level, "Application Set" protocols deal only with how handled