Click here to close now.

Welcome!

AJAX & REA Authors: Pat Romanski, Liz McMillan, XebiaLabs Blog, AppDynamics Blog, Elizabeth White

Related Topics: Security, XML, Microservices Journal, Adobe Flex, Web 2.0

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.

@CloudExpo Stories
In today's application economy, enterprise organizations realize that it's their applications that are the heart and soul of their business. If their application users have a bad experience, their revenue and reputation are at stake. In his session at 15th Cloud Expo, Anand Akela, Senior Director of Product Marketing for Application Performance Management at CA Technologies, discussed how a user-centric Application Performance Management solution can help inspire your users with every applicati...
As enterprises engage with Big Data technologies to develop applications needed to meet operational demands, new computation fabrics are continually being introduced. To leverage these new innovations, organizations are sacrificing market opportunities to gain expertise in learning new systems. In his session at Big Data Expo, Supreet Oberoi, Vice President of Field Engineering at Concurrent, Inc., discussed how to leverage existing infrastructure and investments and future-proof them against e...
The consumption economy is here and so are cloud applications and solutions that offer more than subscription and flat fee models and at the same time are available on a pure consumption model, which not only reduces IT spend but also lowers infrastructure costs, and offers ease of use and availability. In their session at 15th Cloud Expo, Ermanno Bonifazi, CEO & Founder of Solgenia, and Ian Khan, Global Strategic Positioning & Brand Manager at Solgenia, discussed this shifting dynamic with an ...
Due of the rise of Hadoop, many enterprises are now deploying their first small clusters of 10 to 20 servers. At this small scale, the complexity of operating the cluster looks and feels like general data center servers. It is not until the clusters scale, as they inevitably do, when the pain caused by the exponential complexity becomes apparent. We've seen this problem occur time and time again. In his session at Big Data Expo, Greg Bruno, Vice President of Engineering and co-founder of StackI...
Once the decision has been made to move part or all of a workload to the cloud, a methodology for selecting that workload needs to be established. How do you move to the cloud? What does the discovery, assessment and planning look like? What workloads make sense? Which cloud model makes sense for each workload? What are the considerations for how to select the right cloud model? And how does that fit in with the overall IT transformation?
The recent trends like cloud computing, social, mobile and Internet of Things are forcing enterprises to modernize in order to compete in the competitive globalized markets. However, enterprises are approaching newer technologies with a more silo-ed way, gaining only sub optimal benefits. The Modern Enterprise model is presented as a newer way to think of enterprise IT, which takes a more holistic approach to embracing modern technologies.
There is little doubt that Big Data solutions will have an increasing role in the Enterprise IT mainstream over time. 8th International Big Data Expo, co-located with 17th International Cloud Expo - to be held November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA - has announced its Call for Papers is open. As advanced data storage, access and analytics technologies aimed at handling high-volume and/or fast moving data all move center stage, aided by the cloud computing bo...
Every day we read jaw-dropping stats on the explosion of data. We allocate significant resources to harness and better understand it. We build businesses around it. But we’ve only just begun. For big payoffs in Big Data, CIOs are turning to cognitive computing. Cognitive computing’s ability to securely extract insights, understand natural language, and get smarter each time it’s used is the next, logical step for Big Data.
There's no doubt that the Internet of Things is driving the next wave of innovation. Google has spent billions over the past few months vacuuming up companies that specialize in smart appliances and machine learning. Already, Philips light bulbs, Audi automobiles, and Samsung washers and dryers can communicate with and be controlled from mobile devices. To take advantage of the opportunities the Internet of Things brings to your business, you'll want to start preparing now.
Enterprises are fast realizing the importance of integrating SaaS/Cloud applications, API and on-premises data and processes, to unleash hidden value. This webinar explores how managers can use a Microservice-centric approach to aggressively tackle the unexpected new integration challenges posed by proliferation of cloud, mobile, social and big data projects. Industry analyst and SOA expert Jason Bloomberg will strip away the hype from microservices, and clearly identify their advantages and d...
In a world of ever-accelerating business cycles and fast-changing client expectations, the cloud increasingly serves as a growth engine and a path to new business models. Dynamic clouds enable businesses to continuously reinvent themselves, adapting their business processes, their service and software delivery and their operations to achieve speed-to-market and quick response to customer feedback. As the cloud evolves, the industry has multiple competing cloud technologies, offering on-premises ...
The 5th International DevOps Summit, co-located with 17th International Cloud Expo – being held November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA – announces that its Call for Papers is open. Born out of proven success in agile development, cloud computing, and process automation, DevOps is a macro trend you cannot afford to miss. From showcase success stories from early adopters and web-scale businesses, DevOps is expanding to organizations of all sizes, including the...
The OpenStack cloud operating system includes Trove, a database abstraction layer. Rather than applications connecting directly to a specific type of database, they connect to Trove, which in turn connects to one or more specific databases. One target database is Postgres Plus Cloud Database, which includes its own RESTful API. Trove was originally developed around MySQL, whose interfaces are significantly less complicated than those of the Postgres cloud database. In his session at 16th Cloud...
Over the years, a variety of methodologies have emerged in order to overcome the challenges related to project constraints. The successful use of each methodology seems highly context-dependent. However, communication seems to be the common denominator of the many challenges that project management methodologies intend to resolve. In this respect, Information and Communication Technologies (ICTs) can be viewed as powerful tools for managing projects. Few research papers have focused on the way...
As the world moves from DevOps to NoOps, application deployment to the cloud ought to become a lot simpler. However, applications have been architected with a much tighter coupling than it needs to be which makes deployment in different environments and migration between them harder. The microservices architecture, which is the basis of many new age distributed systems such as OpenStack, Netflix and so on is at the heart of CloudFoundry – a complete developer-oriented Platform as a Service (PaaS...
SAP is delivering break-through innovation combined with fantastic user experience powered by the market-leading in-memory technology, SAP HANA. In his General Session at 15th Cloud Expo, Thorsten Leiduck, VP ISVs & Digital Commerce, SAP, discussed how SAP and partners provide cloud and hybrid cloud solutions as well as real-time Big Data offerings that help companies of all sizes and industries run better. SAP launched an application challenge to award the most innovative SAP HANA and SAP HANA...
With major technology companies and startups seriously embracing IoT strategies, now is the perfect time to attend @ThingsExpo in Silicon Valley. Learn what is going on, contribute to the discussions, and ensure that your enterprise is as "IoT-Ready" as it can be! Internet of @ThingsExpo, taking place Nov 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 17th Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading in...
P2P RTC will impact the landscape of communications, shifting from traditional telephony style communications models to OTT (Over-The-Top) cloud assisted & PaaS (Platform as a Service) communication services. The P2P shift will impact many areas of our lives, from mobile communication, human interactive web services, RTC and telephony infrastructure, user federation, security and privacy implications, business costs, and scalability. In his session at @ThingsExpo, Robin Raymond, Chief Architect...
The widespread success of cloud computing is driving the DevOps revolution in enterprise IT. Now as never before, development teams must communicate and collaborate in a dynamic, 24/7/365 environment. There is no time to wait for long development cycles that produce software that is obsolete at launch. DevOps may be disruptive, but it is essential. The DevOps Summit at Cloud Expo – to be held June 3-5, 2015, at the Javits Center in New York City – will expand the DevOps community, enable a wide...
There is no question that the cloud is where businesses want to host data. Until recently hypervisor virtualization was the most widely used method in cloud computing. Recently virtual containers have been gaining in popularity, and for good reason. In the debate between virtual machines and containers, the latter have been seen as the new kid on the block – and like other emerging technology have had some initial shortcomings. However, the container space has evolved drastically since coming on...