Welcome!

Cloud Security Authors: Liz McMillan, Jim Hansen, Peter Silva, AppNeta Blog, Pat Romanski

Related Topics: Cloud Security, Industrial IoT, Microservices Expo, Adobe Flex, Agile Computing

Cloud Security: Article

Capture File Filtering with Wireshark

Needle in a Haystack

Intrusion detection tools that use the libpcap C/ C++ library [1] for network traffic capture (such as Snort [2] and Tcpdump [1]) can output packet capture information to a file for later reference. The format of this capture file is known as pcap. By capturing packet data to a file, an investigator can return later to study the history of an intrusion attempt – or to turn up other important clues about clandestine activity on the network.

Of course, the traffic history data stored in a pcap file is much too vast to study by just viewing the file manually. Security experts use specialized filtering tools to search through the file for pertinent information. One way to look for clues in a pcap file is to use the Wireshark protocol analysis tool [3] and its accompanying command-line utility tshark.

Wireshark is included by default on many Linux distros, and if not, it is available through the leading package repositories. You can also download Wireshark through the project website [4]. In this article, I describe how to use Wireshark and tshark to search a pcap file for information on network activity. I will assume you already have a pcap file ready for investigation. For more on how to capture a pcap file with Tcp-dump, see my article “Intruder Detection with Tcpdump,” which is available online at the ADMIN magazine website [5].

tshark at the Command Line
The tshark utility is a simple tool included with the Wireshark package that lets you filter the contents of a pcap file from the command line. To get a view of the most significant activity, I use the following command:

$ tshark ‑nr dumpfile1.gz ‑qz "io,phs" > details.txt

The ‑n switch disables network object name resolution, ‑r indicates that packet data is to be read from the input file, in this case dumpfile1.gz. The ‑z allows for statistics to display after it finishes reading the capture file, the ‑q flag specifies that only the statistics are printed, and the > redirection
sends the output to the file called details.txt. See Figure 1 for the output of this information. To view a list of help commands used with tshark, type:

$ tshark ‑h

And for a list of ‑z arguments type:

$ tshark ‑z help

Figure 1

Say you would like to know whether a particular IP address appeared in a packet dump and what port it was connecting on. The following command line checks the dump file for the IP address 98.139.126.21:

$ tshark ‑V ‑nr dumpfile.gz ip.src == 98.139.126.21 | grep "Source port" | awk {'print $3'} | sort ‑n | uniq 80

The resulting output on the line following the command shows that the packet dump file recorded IP address 98.139.126.21 having connections on port 80.

If you were given a packet dump file and asked to find possible IRC traffic on your network, how would you do it? First, you would need to know what port numbers were associated with IRC traffic, and that could be accomplished with Google or by issuing the following command:

$ grep irc /usr/share/nmap/nmap‑services | grep tcp

Figure 2 shows the results of the preceding command.

Figure 2

Now I can search the packet dump and look for evidence of IRC traffic using the following commands:

$ tshark ‑nr dumpfile1.gz 'ip.addr==172.16.134.191 and tcp.port >=  6667 and tcp.port <= 6670 and irc' |  awk {'print $3,$4,$5,$6'} | sort ‑n | uniq ‑c

Figure 1: tshark statistics output.
Figure 2: Locating IRC port numbers with grep.
Figure 3: IRC connections found in the packet dump.
Figure 4: The Wireshark startup window.

The breakdown of this command is shown in Table 1, and the output is in Figure 3.

Figure 3

In the GUI
The Wireshark GUI application is easier on the eyes, and it provides some options that aren’t available at the command line. You can start Wireshark from the Application menu or from the terminal.  To load a capture file, select Open in the startup window (Figure 4) or select File | Open from the menubar.  Once you have a packet capture file loaded, you can start searching packet dumps within the Wireshark interface.

Figure 4

The Filter box below the Wireshark toolbar lets you enter criteria for the search. For instance, to search for all the Canonical Name records within the capture file, type in the following filter: dns.resp.type == CNAME (see Figure 5).  After you enter a filter, remember to clear the filter text to see the full file before starting a new search.

Figure 5

Table 1: Parts of a tshark Command

Option Description
‘ip.addr==172.16.134.191         This is my network
and tcp.port >= 6667                   Start of the port range
and tcp.port <= 6670                   End of the port range
and irc’                                           Searches for IRC traffic only
awk {‘print $3,$4,$5,$6’}             Prints the third through sixth patterns from each matching line
sort ‑n                                            Sorts according to string numerical value
uniq ‑c                                            Only prints the number of matches that are unique

Digging deeper, if I want to know how long a client resolver cached the IP address associated with the name cookex.amp.gapx.yahoodns.net (Figure 6), I would enter the following filter:

dns.resp.name == "cookex.amp.gapx. yahoodns.net"

Figure 6

The filter ip.addr == 10.37.32.97 gives information on all communications that involve 10.37.32.97 in the packet dump. If needed, use && to isolate to a specific protocol. The filter ip.dst == 10.37.32.97 or ip.src == 10.37.32.97 looks for a source or destination IP address.

How could I find the password used over Telnet between two IP addresses? For example, if a user at 172.21.12.5 is using Telnet to access a device at 10. 37. 140.160, I can enter:

ip.dst == 10.37.140.160 && ip.src == 172.21.12.5 && telnet.data contains "Password"

The preceding command will list the connections that meet the search requirement, and you can right-click on the packet and click Follow TCP Stream to view the password. (See Figures 7 and 8.)

Figure 7

Figure 8

Note: A much easier way to get the password on the network, if you were sniffing the traffic instead of reading from a capture file, would be to use ettercap, as follows:

$ ettercap ‑Tzq //23

To discover whether someone was viewing a suspicious web page, I can perform a filter search to find out what picture the person at IP address 10.225.5.107 was viewing at Yahoo (216.115.97.236) with the following filter:

ip.dst == 10.225.5.107 && ip.src == 216.115.97.236 && (image‑jfif || image‑gif)

Figure 9

Figure 9 shows the results. If you then right-click on a line in the output and select Follow TCP Stream for the results shown in Figure 10.
The second line in the Follow TCP Stream output specifies that wynn‑ rovepolitico.jpg is the image this person was viewing on the site.

Figure 10

Conclusion
Wireshark can do more than just watch the wires in real time. If you save a snapshot of network activity in a capture file in the pcap format, you can use Wireshark to search through the file to look for clues about nefarious activity.

In this article, I described how to search for information in a capture file using Wireshark and the tshark command-line tool.

Info

[1] Tcpdump and Libpcap: http://www.tcpdump.org/
[2] Snort: http://www..snort.org
[3] Wireshark: http://www.wireshark.org/
[4] Wireshark Download: http://www.wireshark.org/download.html
[5] “Intruder Detection with Tcpdump” by David J. Dodd: http://www.admin‑magazine.com/Articles/Intruder‑Detection‑with‑tcpdump/

More Stories By David Dodd

David J. Dodd is currently in the United States and holds a current 'Top Secret' DoD Clearance and is available for consulting on various Information Assurance projects. A former U.S. Marine with Avionics background in Electronic Countermeasures Systems. David has given talks at the San Diego Regional Security Conference and SDISSA, is a member of InfraGard, and contributes to Secure our eCity http://securingourecity.org. He works for Xerox as Information Security Officer City of San Diego & pbnetworks Inc. http://pbnetworks.net a Service Disabled Veteran Owned Small Business (SDVOSB) located in San Diego, CA and can be contacted by emailing: dave at pbnetworks.net.

@ThingsExpo Stories
Big Data, cloud, analytics, contextual information, wearable tech, sensors, mobility, and WebRTC: together, these advances have created a perfect storm of technologies that are disrupting and transforming classic communications models and ecosystems. In his session at @ThingsExpo, Erik Perotti, Senior Manager of New Ventures on Plantronics’ Innovation team, provided an overview of this technological shift, including associated business and consumer communications impacts, and opportunities it m...
In his keynote at @ThingsExpo, Chris Matthieu, Director of IoT Engineering at Citrix and co-founder and CTO of Octoblu, focused on building an IoT platform and company. He provided a behind-the-scenes look at Octoblu’s platform, business, and pivots along the way (including the Citrix acquisition of Octoblu).
It is one thing to build single industrial IoT applications, but what will it take to build the Smart Cities and truly society changing applications of the future? The technology won’t be the problem, it will be the number of parties that need to work together and be aligned in their motivation to succeed. In his Day 2 Keynote at @ThingsExpo, Henrik Kenani Dahlgren, Portfolio Marketing Manager at Ericsson, discussed how to plan to cooperate, partner, and form lasting all-star teams to change the...
"delaPlex is a software development company. We do team-based outsourcing development," explained Mark Rivers, COO and Co-founder of delaPlex Software, in this SYS-CON.tv interview at 18th Cloud Expo, held June 7-9, 2016, at the Javits Center in New York City, NY.
SYS-CON Events announced today that CA Technologies has been named “Platinum Sponsor” of SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY, and the 21st International Cloud Expo®, which will take place October 31-November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. CA Technologies helps customers succeed in a future where every business – from apparel to energy – is being rewritten by software. From ...
"I think that everyone recognizes that for IoT to really realize its full potential and value that it is about creating ecosystems and marketplaces and that no single vendor is able to support what is required," explained Esmeralda Swartz, VP, Marketing Enterprise and Cloud at Ericsson, in this SYS-CON.tv interview at @ThingsExpo, held June 7-9, 2016, at the Javits Center in New York City, NY.
The buzz continues for cloud, data analytics and the Internet of Things (IoT) and their collective impact across all industries. But a new conversation is emerging - how do companies use industry disruption and technology enablers to lead in markets undergoing change, uncertainty and ambiguity? Organizations of all sizes need to evolve and transform, often under massive pressure, as industry lines blur and merge and traditional business models are assaulted and turned upside down. In this new da...
SYS-CON Events announced today that Fusion, a leading provider of cloud services, will exhibit at SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. Fusion, a leading provider of integrated cloud solutions to small, medium and large businesses, is the industry’s single source for the cloud. Fusion’s advanced, proprietary cloud service platform enables the integration of leading edge solutions in the cloud, including cloud...
SYS-CON Events announced today that Cloud Academy will exhibit at SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. Cloud Academy is the industry’s most innovative, vendor-neutral cloud technology training platform. Cloud Academy provides continuous learning solutions for individuals and enterprise teams for Amazon Web Services, Microsoft Azure, Google Cloud Platform, and the most popular cloud computing technologies. Ge...
In his keynote at 18th Cloud Expo, Andrew Keys, Co-Founder of ConsenSys Enterprise, provided an overview of the evolution of the Internet and the Database and the future of their combination – the Blockchain. Andrew Keys is Co-Founder of ConsenSys Enterprise. He comes to ConsenSys Enterprise with capital markets, technology and entrepreneurial experience. Previously, he worked for UBS investment bank in equities analysis. Later, he was responsible for the creation and distribution of life settle...
The best way to leverage your Cloud Expo presence as a sponsor and exhibitor is to plan your news announcements around our events. The press covering Cloud Expo and @ThingsExpo will have access to these releases and will amplify your news announcements. More than two dozen Cloud companies either set deals at our shows or have announced their mergers and acquisitions at Cloud Expo. Product announcements during our show provide your company with the most reach through our targeted audiences.
SYS-CON Events announced today that Outlyer, a monitoring service for DevOps and operations teams, has been named “Bronze Sponsor” of SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. Outlyer is a monitoring service for DevOps and Operations teams running Cloud, SaaS, Microservices and IoT deployments. Designed for today's dynamic environments that need beyond cloud-scale monitoring, we make monitoring effortless so you...
With 10 simultaneous tracks, keynotes, general sessions and targeted breakout classes, Cloud Expo and @ThingsExpo are two of the most important technology events of the year. Since its launch over eight years ago, Cloud Expo and @ThingsExpo have presented a rock star faculty as well as showcased hundreds of sponsors and exhibitors! In this blog post, I provide 7 tips on how, as part of our world-class faculty, you can deliver one of the most popular sessions at our events. But before reading the...
A strange thing is happening along the way to the Internet of Things, namely far too many devices to work with and manage. It has become clear that we'll need much higher efficiency user experiences that can allow us to more easily and scalably work with the thousands of devices that will soon be in each of our lives. Enter the conversational interface revolution, combining bots we can literally talk with, gesture to, and even direct with our thoughts, with embedded artificial intelligence, whic...
20th Cloud Expo, taking place June 6-8, 2017, at the Javits Center in New York City, NY, will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud strategy.
Bert Loomis was a visionary. This general session will highlight how Bert Loomis and people like him inspire us to build great things with small inventions. In their general session at 19th Cloud Expo, Harold Hannon, Architect at IBM Bluemix, and Michael O'Neill, Strategic Business Development at Nvidia, discussed the accelerating pace of AI development and how IBM Cloud and NVIDIA are partnering to bring AI capabilities to "every day," on-demand. They also reviewed two "free infrastructure" pr...
Have you ever noticed how some IT people seem to lead successful, rewarding, and satisfying lives and careers, while others struggle? IT author and speaker Don Crawley uncovered the five principles that successful IT people use to build satisfying lives and careers and he shares them in this fast-paced, thought-provoking webinar. You'll learn the importance of striking a balance with technical skills and people skills, challenge your pre-existing ideas about IT customer service, and gain new in...
With major technology companies and startups seriously embracing Cloud strategies, now is the perfect time to attend @CloudExpo | @ThingsExpo, June 6-8, 2017, at the Javits Center in New York City, NY and October 31 - November 2, 2017, Santa Clara Convention Center, CA. Learn what is going on, contribute to the discussions, and ensure that your enterprise is on the right path to Digital Transformation.
With major technology companies and startups seriously embracing Cloud strategies, now is the perfect time to attend @CloudExpo | @ThingsExpo, June 6-8, 2017, at the Javits Center in New York City, NY and October 31 - November 2, 2017, Santa Clara Convention Center, CA. Learn what is going on, contribute to the discussions, and ensure that your enterprise is on the right path to Digital Transformation.
TechTarget storage websites are the best online information resource for news, tips and expert advice for the storage, backup and disaster recovery markets. By creating abundant, high-quality editorial content across more than 140 highly targeted technology-specific websites, TechTarget attracts and nurtures communities of technology buyers researching their companies' information technology needs. By understanding these buyers' content consumption behaviors, TechTarget creates the purchase inte...