Packet Captures

Various Pcap files for studies are as follows:

=PCAP files= Common packet captures files used across the site and for studies are below:

Misc Captures
=Filtering Packets= Information related to Packet filtering is as follows:

Filtering a Cap File
dumpcap -i eth0 -f "host 208.67.220.220 and udp port 53" -w /tmp/dns.cap -b duration:3600 -b files:25

Advanced Packet Filtering
Use Case:

I am analyzing an SMB issue. I have 50 PCAP files, each of 100 MB, generated by the intermediate devices. I am not sure which all files contain the interesting traffic. Searching each file manually using wireshark is hectic. Client addresses are 1.1.1.1 and 2.2.2.2. Server address is 3.3.3.3. Protocol is SMB2 (port 445). We can use Tshark or TCPDump for this exercise. Tshakr is slow in Linux & TCPDump is very fast. Wireshark Filter: ((ip.addr==1.1.1.1 or ip.addr==2.2.2.2) and ip.addr==3.3.3.3) and smb

List all Pcap files using any of the below commands: find. -type f | egrep "All.pcap" find. -type f | egrep ".pcap" find. -type f | egrep "*.pcap" find. -type f | grep ".pcap" find. -type f | grep "pcap"

List interesting traffic from all the PCAP files:  for i in `find. -type f | egrep "All.pcap"`; do echo $i; tshark -r $i '((ip.addr==1.1.1.1 or ip.addr==2.2.2.2) and ip.addr==3.3.3.3) and smb' ; echo -e "\n"; done

Filter out errors:  for i in `find. -type f | egrep "All.pcap"`; do echo $i; tshark -r $i '((ip.addr==1.1.1.1 or ip.addr==2.2.2.2) and ip.addr==3.3.3.3) and smb2' ; echo -e "\n"; done | grep -E '(error|unknown|denied)'

Filter out errors and save output to text file in backgroup:  for i in `find. -type f | egrep "All.pcap"`; do echo $i; tshark -r $i '((ip.addr==1.1.1.1 or ip.addr==2.2.2.2) and ip.addr==3.3.3.3) and smb2' ; echo -e "\n"; done | grep -E '(error|unknown|denied)' > errors.txt &

Show Timestamps in the output and save it to a text file:  for i in `find. -type f | egrep "All.pcap"`; do echo $i; tshark -t ad -r $i '((ip.addr==1.1.1.1 or ip.addr==2.2.2.2) and ip.addr==3.3.3.3) and smb2' ; echo -e "\n"; done > smb-time.txt

a      absolute time (local time in your time zone, actual time the packet was captured) ad     absolute with date u      Absolute UTC time ud     Absolute UTC time with date

Search for keyworks in hte text files created along with traces: for i in `find. -type f | egrep ".txt"`; do echo $i; cat $i ; echo -e "\n"; done | grep smb2.lock

Using TCPDump instead of Tshark  for i in `find. -type f | egrep "All.pcap"`; do echo $i; tcpdump -r $i '((host 1.1.1.1 or host 2.2.2.2) and host 3.3.3.3) and port 445' ; echo -e "\n"; done

= Misc =


 * In IE, disable HTTP1.1 in Advanced options to see the traffic being sent in HTTP1.0 version. Now you will be able to see traffic in Clear text in wireshark captures. HTTP1.1 uses gzip to compress html, so it is not read in clear text. You will find multiple connections for a single webpage.


 * In Wireshark, anyting you see in square brackets - [bla bla] is the wireshar analysis of the information & is not the part of the packet captured.

Non-Root Capture in Ubuntu
sudo apt-get install libcap2-bin sudo groupadd wireshark sudo usermod -a -G wireshark kirat newgrp wireshark sudo chgrp wireshark /usr/bin/dumpcap sudo chmod 750 /usr/bin/dumpcap sudo setcap cap_net_raw,cap_net_admin=eip /usr/bin/dumpcap

Verification: getcap /usr/bin/dumpcap    =>   /usr/bin/dumpcap = cap_net_admin,cap_net_raw+eip

If still unable to capture: sudo dpkg-reconfigure wireshark-common sudo chmod +x /usr/bin/dumpcap

Tshark
apt-get install tshark tshark -r lotsapackets.cap -R dns -w dns.cap tshark -r lotsapackets.cap -R "dns or tcp.port==80" -w web.cap capinfos web.cap editcap -c 50000 lotsapackets.cap fewerpackets.cap