Difference between pages "Tutorials/Tutorial: Packets don't lie: how can you use tcpdump/tshark (wireshark) to prove your point." and "Home Automation BoF"

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===PREREQUISITES===
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Come and discuss Home Automation including all things Sensors, Collection, Graphing, Control & Open Hardware
Please note that this is a tutorial, not a talk.
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You should have tcpdump and wireshark INSTALLED and do some captures BEFORE you come to the tutorial.
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To find wireshark packages do something like this:
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<pre>
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#archlinux
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pacman -Ss wireshark tcpdump
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#debian
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apt-cache search wireshark tcpdump
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#fedora
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yum search wireshark tcpdump
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</pre>
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Please install both GUI and CLI packages.
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Please add the user you are going to run wireshark/tshark as to the 'wireshark' user group.  
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[[https://twitter.com/lathiat Trent Lloyd]] can briefly re-run his lightning talk from open hardware on graphing everything in his house and programming a BLE dev board on Linux
<pre>
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gpasswd -a james wireshark
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</pre>
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After this user 'james' will need to log out and log in again!
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Then let's discuss what everyone else is doing, show off with photos if you have some, etc.
  
If that still DOESN'T work,  you might want to add a capability. Do it ONLY if you are still unable to do capture.
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If you are coming then please note below and include anything you can talk about, would like to hear about, or just your name to come and enjoy the discussion.
<pre>
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setcap cap_net_raw,cap_net_admin=eip /usr/bin/dumpcap
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</pre>
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When finished, have a look around at what files came with the package:
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<pre>
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tcpdump --version
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tshark --version
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</pre>
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List binaries that came with the packge (example is for archlinux, for rmp-like do 'rpm -ql wireshark', for debian 'dpkg -L wireshark')
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<pre>
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pacman -Ql wireshark-cli|grep bin
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wireshark-cli /usr/bin/androiddump
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wireshark-cli /usr/bin/capinfos
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wireshark-cli /usr/bin/captype        #same as 'capinfos -t'
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wireshark-cli /usr/bin/dftest        #display filter byte-code for debugging
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wireshark-cli /usr/bin/dumpcap        #can write files
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wireshark-cli /usr/bin/editcap        #snaplenth, or split into multiple based on time, number of packets, adjust time
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wireshark-cli /usr/bin/idl2wrs
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wireshark-cli /usr/bin/mergecap
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wireshark-cli /usr/bin/randpkt        #creates a legitimate EthernetII packet with the given Type field set
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wireshark-cli /usr/bin/rawshark      #cannot write files, only to standard output
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wireshark-cli /usr/bin/reordercap    #part of the functionality of the editcap
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wireshark-cli /usr/bin/text2pcap      #hexdump -> pcap
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wireshark-cli /usr/bin/tshark
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wireshark-cli /usr/include/wireshark/epan/dissectors/packet-ypbind.h
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wireshark-cli /usr/share/wireshark/radius/dictionary.bintec
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</pre>
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=Capturing=
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====browsing exercise ====
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# start capturing
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# navigate your browser to linux.conf.au
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# navigate your browser to google.com
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# navigate your browser to xxxxxxx (your choice)
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====have a look at the capture files that you generated====
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<pre>
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capinfos -T *.pcap{,ng}
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</pre>
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==capture interfaces==
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<pre>
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tcpdump -D
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tshark -D
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# try with no interface
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tshark
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</pre>
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==capturing on the CLI==
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tcpdump can autostop after certain number of packets has been captured. tshark has addinionally duration, filesize and number of files autostop conditions.
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What if we want to have a permanent capture running and keep last N days of the logs?
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<pre>
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tshark -b duration:2 -n -wevery2sec.pcapng & watch -n 1 ls -l
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tshark -b duration:2 -n -wevery2sec.pcapng -a files:5  & watch -n1 ls -l
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tshark -b duration:3600 -n -weveryHour.pcapng -b files:24
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tshark -a filesize:1024 -n -w1MiB.pcapng
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</pre>
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=expert info=
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==GUI==
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-r <pcap file>
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-J  <jump filter>
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          After reading in a capture file using the -r flag, jump to the packet matching the filter (display
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          filter syntax).  If no exact match is found the first packet after that is selected.
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        capinfo
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        lower bottom corner
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                expert info
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                file name
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                packets, etc
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        statistics -> protocol hierarchy
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        statistics -> HTTP -> packet counter
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        statistics -> HTTP -> requests
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        extract objects
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        follow TCP stream
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        coloring rules
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        Statistics -> IPv4 Statistics ->  Destinations and  Ports
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fields
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    delta time
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==CLI==
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<pre>
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! tshark -q -z ptype,tree
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! tshark -q -z io,stat,20,eth -q
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! tshark -q -z io,stat,20,http -q
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! tshark -q -z io,stat,20,,"BYTES()http" -q
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! tshark -q -z http,tree
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! tshark -q -z http_req,tree
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! tshark -q -z http_srv,tree
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create a capture file for icmp
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! tshark -q -z icmp,srt
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! tshark -q -z io,phs
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! tshark -q -z io,stat
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! tshark -q -z ip_hosts,tree
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! tshark -q -z plen,tree
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! tshark -q -z endpoints,eth
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! tshark -q -z endpoints,eth,
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! tshark -q -z endpoints,ip
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! tshark -q -z conv,eth
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! tshark -q -z conv,udp
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! tshark -q -z conv,tcp
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! tshark -q -z conv
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! tshark -q -z expert,error -q
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! tshark -q -z expert,note -q
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</pre>
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=DECRYPTING SSL=
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When a client (for example, a web browser) makes a connection to a web server requiring SSL/TLS encryption - the encrypted channel is setup using a '''symmetric''' session key. This key is a random string generated by the client and then encrypted and transmitted using the servers '''public''' key, known as the ''Pre-master Secret''. Once shared, the client and server use this shared key to encrypt and decrypt traffic.
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MacOS users can do: launchctl setenv SSLKEYLOGFILE /tmp/SSLKEYLOGFILE.txt; open -a Applications/Firefox.app
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====exercise on decyphering SSL====
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# <pre>
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SSLKEYLOGFILE=/tmp/SSLKEYLOGFILE.txt firefox &  tail -f /tmp/SSLKEYLOGFILE.txt
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</pre>
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#Navigate to https://google.com
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#Do some searches
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#Start capture
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#Open a new tab and do more searches on google.com
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#try https://facebook.com or some other web site.
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SSLKEYLOGFILE variable  works for firefox, chromium and any program built with NSS library (Network Security Services).
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==display filter==
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<pre>
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sack
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http
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        ip.src==1.1.1.1 &&      tcp.analysis.retransmission or tcp.analysis.fast_retransmission
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        http.time >= 0.4
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        tcp.analysis.rto >= 0.050
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        http.request.uri == "https://www.wireshark.org/"
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        http.response.code == 500
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        tcp.port in {80 443 8080}
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        #the above is same as:
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        tcp.port == 80 || tcp.port == 443 || tcp.port == 8080
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        _ws.expert.severity >= warn
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                0x1      ok
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                0x100000 comment
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                0x200000 chat
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                0x400000 note
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                0x600000 warn
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                0x800000 error
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tshark -r /var/tmp/aros.pcapng -e frame.number -e ip.src -e ip.dst -Tfields
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tshark -r /srv/http/TCP_SACK.cap  -Y frame.number==29 -V
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tshark -r TCP_SACK.cap -Y 'frame.number>=10' -Y 'frame.number<=15'
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</pre>
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==columns==
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<pre>
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tshark -r http.pcapng -z follow,tcp,hex,1
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tshark -e ip.addr -e tcp.window_size -Tfields
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tshark -r http.pcapng -z follow,tcp,hex,127.0.0.1:59544,127.0.0.1:80
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tshark -r /srv/http/TCP_SACK.cap  -Tfields -e frame.number -e frame.time_epoch -e ip.src -e ip.dst -e tcp.seq -e tcp.len -e tcp.nxtseq -e tcp.ack  -e tcp.analysis.ack_rtt
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tshark -r /srv/http/TCP_SACK.cap  -Tfields -e frame.number -e frame.time_epoch -e ip.src -e ip.dst -e tcp.seq -e tcp.len -e tcp.nxtseq -e tcp.ack  -e  tcp.options.sack_le -e tcp.options.sack_re
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</pre>
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=extra=
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<pre>
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-d tcp.port==8888,http
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</pre>
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Revision as of 17:45, 3 February 2016

Come and discuss Home Automation including all things Sensors, Collection, Graphing, Control & Open Hardware

[Trent Lloyd] can briefly re-run his lightning talk from open hardware on graphing everything in his house and programming a BLE dev board on Linux

Then let's discuss what everyone else is doing, show off with photos if you have some, etc.

If you are coming then please note below and include anything you can talk about, would like to hear about, or just your name to come and enjoy the discussion.