Author Archives: Gerald Combs

Dedication and Disagreements

As I’ve mentioned in many of my talks about the Wireshark project, our primary goal is to help as many people as possible understand their networks as much as possible. We’ve been very fortunate over the years in this regard. Many people are passionate about this goal and have dedicated themselves to help to work toward it.

Although a group of people might agree about a particular goal, they can sometimes disagree about how to get there. When you add in personal dedication and investment, the disagreement can take on a life of its own. This happened to us recently.

Years ago when I worked at CACE Technologies we created the Wireshark Foundation1. A couple of years later, Laura Chappell came up with the idea for Wireshark University and the WCNA certification program. She worked out an agreement with CACE’s CEO to license use of Wireshark’s trademarks which they subsequently signed.

Shortly after that, Riverbed acquired CACE, along with the Wireshark Foundation. Like CACE, Riverbed has been both supportive of the project and hands-off. They pay my salary, fund SharkFest and our infrastructure, and have done so since the acquisition. We always strive to do more, and last fall it was suggested that we might be able to bring in extra money to fund more initiatives which would improve Wireshark and benefit the community.

One of the ideas for extra revenue involved restructuring Wireshark University in the hopes of including more educators. We presented the plan to Laura, and it didn’t go well. Our relationship deteriorated to the extent that Laura now maintains that Riverbed has taken over Wireshark. I love and respect her and will be forever grateful for what she’s done for the Wireshark community, but I strongly disagree with this viewpoint.

Riverbed has and continues to be very hands-off with Wireshark and is dedicated to our independence. They don’t dictate our roadmap or otherwise try to push us in a particular direction2. In my keynote3 at SharkFest ’19 US, I talked about creating an independent entity for the Wireshark Foundation and our assets, and they’ve been supportive of the entire process.

Going Forward

Although we weren’t able to come to an agreement on Wireshark University, there was never any question that Laura is welcome to keep using the Wireshark trademark to describe the purpose of her training courses, books, and the WCNA certification program. I would personally prefer that she continue to use the name “Wireshark Certified Network Analyst” — we would just need to have a proper agreement in place. If any of this wasn’t made clear to her over the past few months then that’s on me.

Please don’t let this dissuade you from buying Laura’s books, attending her classes, or going through the WCNA program. She’s a great educator and we share her passion for helping people understand their networks.

Also please be assured that Wireshark is and will always remain Free and Open Source Software. I am forever grateful to our global group of enthusiastic developers who continue to evolve the project. However, stuff costs money, and some of the initiatives we’ve discussed include (but aren’t limited to) hiring support staff. In order to serve the user and developer community and fund the project we must explore options such as charging for non-exclusive use of the Wireshark University trademark.

[1] I don’t recall the precise reason, but it was most likely to reduce CACE’s exposure in the event that I left the picture. They were betting the farm on Wireshark. It should be noted that my daughter and I were on Southwest flight 812, so this wasn’t an unreasonable concern.
[2] Aside from the occasional bug report from one of my co-workers. 🙂
[3] See the “Sustainability” the keynote at https://sharkfestus.wireshark.org/sf19, about 36:15 in.

Wireshark Is Now Twenty

Twenty years ago today I announced Ethereal 0.2.0, which marks the first public release of what is now Wireshark. The release was an attempt at two things: to create an interactive protocol analyzer for Linux and Solaris so that I could do my job better, and to give back to the open source community. As it turns out the second goal had a huge effect on the first one. After the initial release developer and user communities quickly formed. Different people had different goals such as support for other platforms and protocols, troubleshooting in specific environments, education, product development, network forensics, and so on. After a while things settled down to a single goal:

To help as many people as possible understand their networks as much as possible.

As goals go that’s pretty broad and implies a lot of work. Open source project hosting services didn’t exist in 1998 so in the olden days we pretty much ate sand. For example, I made thirty releases in the first year. Twenty of them were first two months. That’s because I was our revision control system1. Contributors would send me patches, I’d apply them to my source tree and then make a release. Everyone would then sync their source directories with the new release. Fortunately we stopped doing that in short order. Other parts of the project followed similar paths. The first Windows packages were ZIP files with no capture driver. Our first web server was a 40 MHz SPARCstation IPX with 64 MB of RAM. We inflicted X11 on our macOS users far longer than we should have.

The project grew from those humble beginnings to what is today – the world’s most popular network protocol analyzer. The goal is still there, and many people and organizations are helping us achieve it. We have a wonderful sponsor in Riverbed, which pays my salary, provides our infrastructure, and sponsors SharkFest, our developer and user conference2. It’s managed by Janice Spampinato, who does a spectacular job of making sure our community can share its knowledge face to face in a welcoming environment. Speaking of SharkFest, we’re having three of them this year! Laura Chappell does a correspondingly spectacular job with Wireshark University, educating users throughout the year. Our user and developer community is second to none in its expertise, knowledge, and willingness to help.

I could not be more proud of what we’ve accomplished and look forward to the challenges and opportunities. On behalf of the Wireshark development team, thank you for your support.


1. Never, ever do this. If you want to start a project, just commit your code to GitLab. Or GitHub. Or BitBucket. Or anything else that doesn’t involve manual patching.

2. If your career involves looking at packets you should maybe show up once in a while.

The Cloudflare Incident And Its Impact On Wireshark.org

Cloudflare recently announced a security incident that potentially impacts anyone who visited various wireshark.org and winpcap.org sites for the past six months.

What happened?

Cloudflare is a popular service that provides content delivery, DDoS protection and DNS services for web sites.

A software bug Cloudflare’s servers leaked potentially sensitive information. Some of that information ended up in caches all over the Internet. At Google, Microsoft, your ISP, your company’s or university’s proxy servers, and elsewhere. Due to the randomness and distributed nature of the bug, it’s difficult to know what the full impact is. Cloudflare provides the following estimate:

“The greatest period of impact was from February 13 and February 18 with around 1 in every 3,300,000 HTTP requests through Cloudflare potentially resulting in memory leakage (that’s about 0.00003% of requests).”

The bug was introduced on September 22, 2016 and fixed on February 18th, 2017.

The Google Project Zero bug describing the issue in detail can be found at https://bugs.chromium.org/p/project-zero/issues/detail?id=1139

Cloudflare’s incident report can be found at https://blog.cloudflare.com/incident-report-on-memory-leak-caused-by-cloudflare-parser-bug/

The initial Hacker News discussion can be found at https://news.ycombinator.com/item?id=13718752

Was Wireshark affected?

The following wireshark.org and winpcap.org sites were behind Cloudflare proxies during the period in question:

  • ask.wirehsark.org
  • blog.wireshark.org
  • bugs.wireshark.org
  • sharkfest.wireshark.org
  • sharkfesteurope.wireshark.org
  • wiki.wireshark.org
  • www.wireshark.org
  • www.winpcap.org

Wireshark’s download servers (*.dl.wireshark.org), buildbot.wireshark.org and code.wireshark.org were not behind Cloudflare.

I browsed to a one of the sites listed above between September 22nd, 2016 and February 18th, 2017. Am I affected?

The chances are slim, but those chances are not zero.

Most of the content that we serve is “static” and “public.” That is, it’s the same for everyone and doesn’t contain any sensitive information. The risk exposed by Cloudflare is from dynamic content that contains sensitive information such as the login page on ask, bugs, wiki, etc. Our web sites get frequent requests for static content, but dynamic requests are relatively infrequent.

In a world where everyone has infinite free time I would have no qualms about recommending that everyone with a wireshark.org account change his or her passwords. However, this is the real world and your time is valuable. If you logged in to one of our sites and used a unique password it might not be worth your time to change it. On the other hand, if your professional reputation depends on your ask.wireshark.org score you probably should. If you have any sort of administrative access you definitely should. Most of our users fall into the first category.

If you’re wondering why it looks like I’m downplaying the importance of changing your wireshark.org passwords, see the next question.

I used a web browser, smart phone, or an internet-connected wearable doohickey between September 22nd, 2016 and February 18th, 2017. Am I affected?

I honestly don’t know. The chances are almost certainly not zero.

Cloudflare is a very popular service. At the time of this writing an unofficial list of affected sites stands at more than four million entries and counting. It includes many of the world’s most popular web sites.

If you’re going to spend time changing passwords, doing so for sites that deal with finance, email, DNA testing, dating, and other parts of your personal life probably ranks higher than that for, say, the Wireshark wiki.

Isn’t a vague answer like “the chances are slim but not zero” a frustratingly craptastic one compared to a definitive “yes” or “no”?

Yes, but it’s also the honest and correct one.

Update: March 2, 2017

Yesterday Cloudflare posted an update on the issue at https://blog.cloudflare.com/quantifying-the-impact-of-cloudbleed/. In it they posted the following leak estimates:

 Requests per Month       Anticipated Leaks
 ------------------       -----------------
        200B – 300B         22,356 – 33,534
        100B – 200B         11,427 – 22,356
         50B – 100B          5,962 – 11,427
          10B – 50B           1,118 – 5,926
           1B – 10B             112 – 1,118
          500M – 1B                56 – 112
        250M – 500M                 25 – 56
        100M – 250M                 11 – 25
         50M – 100M                  6 – 11
          10M – 50M                   1 – 6
              < 10M                     < 1

The affected wireshark.org web sites get just over 10M requests per month combined. Private traffic is substantially less than that.

Getting Ready for SharkFest ’16

The week leading up to SharkFest is always a busy and hectic time around here, but it’s also exciting. I can’t wait to see everyone, and the talks and labs this year promise to continue our tradition of imparting protocol analysis knowledge and insight.

If you’re sill unsure about attending, perhaps this list of reasons for attending that Laura Chappell recently posted will sway you:

1. Gerald Combs and the Wireshark Developers

Gerald Combs, the creator of Wireshark (formerly Ethereal), and many of the core developers will be there actually working on the code in the Developer’s Den. They will be presenting many of the sessions, joining in on the social events (they are a fun group!) and sharing tips and techniques to improve your analysis process.

2. Wireshark Experts as Presenters and Varied Content Levels

There is no dispute that the presenters at SharkFest are the world-authorities on troubleshooting, security analysis, and network optimization. These are the folks who live in the world at packet-level  and can spot a rogue packet at 50 paces! Through a variety of introductory through advanced lectures and hands-on labs, these presenters will show you some hot Wireshark techniques to speed up your time to resolution.

3. Focus on Wireshark 2

It’s time to move up to Wireshark 2. All the presentations and labs at SharkFest ’16 will be focused around the new version of Wireshark. From new features to new techniques, accelerate your migration to Wireshark 2 by getting an inside look at how the experts work their magic.

4. The Reef at SharkFest

I will be hosting The Reef again at SharkFest. The Reef will host hands-on lab exercises, numerous Wireshark University Certified Instructors, Wireshark experts, and Wireshark Developers. Come in and try your hand at the labs and pick up the SharkFest Packet Challenge. This is a great opportunity to mingle amongst Wireshark gurus and hone your troubleshooting and network forensics skills.

5. Hands-On Labs

Get your hands dirty in one of the lab sessions at SharkFest. This year we have added a 100-seat hands-on classroom to SharkFest. This is in addition to the 300+ seater Hahn auditorium. We will also have numerous lab exercises hosted in the Reef and folks to help out on the more challenging labs.

6. Social Events and Peer Networking

The SharkFest team has put together a Welcome Dinner, Vendor Night Party, “Sake’s Surprise” Dinner, and Closing Reception to give you plenty of time to network with other analysts. The casual atmosphere of the Grand Hall lunch area and the Reef offer plenty of opportunities to meet and mingle with other attendees and the developers.

7. Packet Challenge

Again, you will have the chance to test your skills in the SharkFest Packet Challenge. Pick up the Challenge Worksheet in the Reef and grab the USB stick filled with trace files. Turn in your answers in the Reef by Wednesday evening and join us for the Packet Challenge Awards Ceremony in the closing keynote timeslot.

8. Analysis-Focused Vendors

Vendor night is a highlight of the event. As the band plays and the food sizzles on the grill, visit the vendors who sponsor SharkFest. Each vendor is focused on network analysis, troubleshooting, security, optimization and other related topics. These are the folks we all work with to build the most effective analysis environments possible.

9. Computer History Museum and the Revolution

Considered one of the world’s best collection of historical objects relating to the computer industry, the Computer History Museum is a must-see destination for folks in the tech industry! During SharkFest, you will have time to visit the Revolution exhibit to see history in the making. This is our second year at the Computer History Museum – it’s an amazing venue.

10. Sake’s Surprise

I can’t wait to give you more details on this one. Right now, the surprise is in development. It should really be a highlight at SharkFest ’16. As soon as I’m allowed to spill the beans, I will!

11. Troubleshooting with Wireshark Pre-Conference Class

As an extra here, I will be teaching a 3-day class just before SharkFest. The focus is troubleshooting, troubleshooting, troubleshooting! Get the bundle pricing for SharkFest and the 3-day class at https://sharkfest.wireshark.org/registration16.html.

If you can’t attend SharkFest U.S., these reasons also apply to SharkFest Europe. If you are attending either conference, I’ll see you there!

Let me tell you about Wireshark 2.0

We’re getting ready to release Wireshark 2.0, which includes a major user interface update. As a comparison, here’s a picture of Wireshark 1.12.8, which is the current stable release:
Main window 1.12.8

Here’s a picture of Wireshark 2.0.0rc2, which is the current development release:
Main window 2.0.0rc2

See? Totally different.

Actually, quite a few things have changed. The user interface has been completely rewritten using a different interface library (Qt). It has been streamlined so that you can work faster and it should have a better look and feel on every platform. The screenshots above are similar because we’ve also tried to ensure that the new UI is familiar to current users. The features you’re used to are still there and in the same place (or at least nearby). They should work much more smoothly, however.

I can’t hope to cover all of the changes in Wireshark 2.0 in one blog post, but here are a few highlights:

Capture options. Capture options have been simplified and consolidated. In 1.12 they are spread out in many places across several windows. In 2.0 they are in two places: the Capture Options dialog (Capture→Options or the “gear” icon in the toolbar) and the Manage Interfaces dialog, which you can open by pressing “Manage Interfaces” in the Capture Options dialog.

Streamlined preferences. Preferences windows usually aren’t something to get excited about and this is no exception, but it’s important to note that in the process of removing clutter some preferences have been removed from the main window. They’re still available in the “Advanced” preference section which lists every available preference item.

Translations. Thanks to the hard work of many contributors the new interface supports multiple languages. You can now select between Chinese, English, French, German, Italian, Japanese, and Polish in the “Appearance” preferences section. Many more translations are underway. You can see the status the translation efforts and help out with the effort at https://www.transifex.com/wireshark/wireshark/.

Related packets. As you scroll through the packet list you might notice little symbols pop up along its left edge. For example, you might see left and right arrows for DNS requests and Replies, or a check mark to denote an ACKed TCP packet. These are related packets. This exposes some plumbing we’ve had in place for a long time, but it’s now shown in the main window instead of buried deep in the packet detail tree.

Intelligent scrollbar. As you scroll through the packet list you might notice that the scroll bar itself looks odd. It now features a map of nearby packets, similar to the “minimap” available in many modern text editors. The number of packets shown in the map is the same as the number of physical vertical pixels in your scrollbar. The more pixels you have, the more packets you can see. In other words, if you use Wireshark regularly you now have a legitimate business case for a retina display.

Statistics dialogs. The dialogs under the Statistics and Telephony menus have seen many improvements. The backend code has been consolidated so that most of Wireshark’s statistics now share common internal logic. This in turn let us create common UI code with many workflow improvements and a much more consistent interface.

I/O Graph dialog. You can now graph as many items as you like and save graphs as PDF, PNG, JPEG, and BMP. Graph settings stay with your profile so you can customize them for multiple environments.

Follow Stream dialog. You can now switch between streams and search for text.

General dialogs. Many dialogs now have context-aware hints. For example the I/O Graph and Follow Stream dialogs will tell you which packet corresponds to the graph or stream data under your cursor. Most of them will stay open after you close a capture file so that you can compare statistics or graphs between captures.

If you want to see a live demonstration of the new UI, Laura Chappell and I are presenting a webinar next week on the 12th at 10:00 AM PST. You can register at http://bit.ly/wireshark2.

The final 2.0.0 release should be available in a couple of weeks. I’m excited about the new UI and about the opportunities that it provides for new features and further improvements.

Detecting Heartbleed Traffic

The big news in the tech industry this week is The Heartbleed Bug, a vulnerability that affects a large portion of secure web sites on the Internet. I updated the Wireshark and WinPcap web sites on Monday (along with reissuing and revoking certificates) shortly after OS patches were released.

Our web sites are protected going forward, but what about the past? We have a Shark appliance in our environment but that leads to a challenge. We had about 350 GB of HTTPS on our network on Monday alone. This is just slightly too large to load into Wireshark.

Fortunately one of my coworkers (P.J. Malloy) came up with a BPF filter that matches Heartbleed traffic:

http://www.riverbed.com/blogs/Retroactively-detecting-a-prior-Heartbleed-exploitation-from-stored-packets-using-a-BPF-expression.html

Applying this filter directly on the Shark appliance gave me a much smaller number of packets which I could easily analyze in Wireshark. So far I haven’t found anything suspicious.

We’re switching to Qt.

Today I released the next development version of Wireshark, 1.11.0. This marks a major change in the direction of the project. We’re switching our user interface library from GTK+ to Qt. Both libraries make it easy for developers write applications that will run on different platforms without having to rewrite a lot of code. GTK+ has had a huge impact on the way Wireshark looks and feels and on its popularity but it doesn’t cover our supported platforms as effectively as it should and the situation is getting worse as time goes on.

Making such a large change wasn’t an easy decision. It means rewriting thousands of lines of code and requires a lot of careful design. We might be the largest standalone application to make this transition (feel free to correct me below). However, I think it’s well worth it and that it’s important to the long-term direction of the project. Ultimately it came down to one thing:

Wireshark’s job is to show you what’s happening on your network. If it can’t run on your system then it’s not doing that job.

If you’re using Windows, Mac OS X, or Linux Mint we need to support Windows, Mac OS X, and Linux Mint. If you’re using an iPad or a Galaxy Note we need to give you a long, hard, nonplussed stare and think about supporting IOS and Android at some point.

When I started writing Ethereal (Wireshark’s original name) it looked like this:

ethereal-0.2.0

It looked like that on Linux and Solaris. It didn’t look like that anywhere else because those were the only two platforms we supported. I chose GTK+ for the user interface toolkit because it made the most sense. Compared to the options available at the time it had a number of advantages. It was small, light, easy to work with, had an active development team, and had a compatible license. A short time later we added support for Windows. GTK+ had some initial compatibility issues on Windows but it has gotten better over time.

Since then the platform landscape has changed but unfortunately GTK+ hasn’t. Most notably Mac OS X has gained popularity and people are starting to ask about Wireshark for their tablets. GTK+ supports OS X but it’s definitely a second-tier platform, making it hard to install and use. We either have to require X11 (like Inkscape) or use an experimental native GTK+ port (like GIMP). Either way it requires a lot of effort on the part of developers to produce a substandard application for users. With GTK+ Wireshark doesn’t look or act at all like a Mac OS X application:

osx-x11

Qt on the other hand provides a nice, clean user experience on all of the platforms that we currently support. If you install the 64-bit version it now looks like this:

osx-qt

What does this mean for users?

If you’re a power user you should probably keep using the GTK+ flavor for the time being. You should also test the Qt flavor from time to time to see how your workflow will change. Both are installed by default on Windows and Linux.

If you’re running OS X you should use the Qt flavor. For common tasks it should have a better workflow. Again, if it doesn’t we aren’t doing our job.

What does this mean for developers?

If you’re developing a new feature using GTK+ you should stop. You’re very likely wasting your time. If you would like to help with the migration grab the code and start developing.

What works?

Everything under the “File” and “Edit” menus.

You can capture, filter, and inspect traffic.

You can edit preferences.

You can follow streams.

You can view TCP stream graphs.

What doesn’t work?

Everything else. No capture options, I/O graphs, flow graphs, VoIP analysis, etc. We still have a lot of work to do.

Switching to Qt is a long and arduous process but I’m excited about what the future holds.

P.S. Solaris is still supported.

solaris-qt

Fifteen Years

Fifteen years ago I released a little network protocol analyzer. At the time it wasn’t very special. It only dissected five protocols and only ran on Linux and Solaris. I decided to share it with the world and released it as open source. I made use of quite a bit of open source software at that point (and still do), and it seemed like a good way to give back to the community.

Immediately after the release an amazing thing happened I started receiving code from people around the world. They had problems similar to mine and were able to modify the little analyzer to suit their needs. They were also kind enough to contribute those modifications back. Those contributions haven’t stopped to this day and Wireshark has grown into a mature, feature-rich, award-winning network analysis tool. People around the world use it to troubleshoot networks, develop software and protocols, and to learn about networking.

Wireshark has been a source of pride many times over the years but I’m particularly proud of two accomplishments. First, your network is not a black box. This is important inasmuch as our daily lives depend on networks operating efficiently, reliably and securely. Wireshark lets you peer into your network and see how it operates at a low level. It’s also accessible. Anyone can download and run it. Protocol analysis is a fascinating world and if you don’t understand what you’re looking it we have a large community of users and educators that can help you.

Second, it turns out that a protocol analyzer makes a great open source project and Wireshark is an example of open source at its best. People who know a lot about protocols are typically know how to write software. If you provide a platform that allows them to give meaning and context to the bits and bytes that make up network packets they will do so on a massive scale. Wireshark now supports over 1,000 protocols and 140,000 different protocol fields and those numbers keep growing.

We’ve had quite a few challenges in the past and we still do. These days all of your interesting traffic is either off in the cloud or speeding across your LAN at multiple gigabits a second. Wireshark doesn’t run on my tablet and it looks awful on my Macbook. However, these are solvable problems and I’m looking forward to the challenge of fixing them.

When I made that first release I had no idea how big it would become or how much it would impact my life. Wireshark is a great and wonderful thing due to the following people:

  • The development team, who seem to generate an endless stream of brilliance and cleverness.
  • The user community, for their knowledge and enthusiasm, and for putting up with the odd wart here and there.
  • Educators, researchers, developers, and everyone else who help people peer into their networks.
  • My employer for sponsoring the project and being such an awesome place to work, and my co-workers for their passion for network performance.
  • My family and friends, for their support and encouragement over the years.

It’s been a wonderful journey so far and I can’t wait to see what lies ahead. Thank you all.

Sharkfest ’12 Recap

The fifth annual Sharkfest wrapped up a couple of days ago. You are no doubt feeling terrible if you missed it. Don’t despair, you can find a retrospective at the Sharkfest web site. The events team tried to make sure each session was recorded so we should have videos to go along with the slides soon.

As usual I wanted to attend more presentations than physics allowed but unfortunately missed some, so I’m waiting for the retrospective videos along with everyone else. (Hansang Bae observed that this is one of the few conferences where presenters attend other sessions.) Here are some quick notes about the sessions I was able to attend:

Monday’s keynote was delivered by Cliff Stoll. He kept insisting that he didn’t have much to say while simultaneously delivering an informative and entertaining talk.

Steve Riley provided a lot of insights into cloud computing: how it’s changing computing and how it can best be utilized.

Loris Degioanni (aka my boss) gave a great presentation on the new platform API that some people have been working on here at Riverbed. I think this is going to be a must-have once people realize the cool and crazy ways that this can be leveraged.

Wireless was well-represented Thomas D’Otreppe taked about OpenWIPS-ng, his new wireless IPS/IDS project. Metageek’s Ryan Woodings talked about wireless below the packet level. Mike Kershaw and Michael Ossman talked about the development of the Kisbee and Ubertooth adapters, and how you too can design and implement real hardware devices.

Hansang Bae showed modern TCP stacks and network devices can collude to make connectivity really slow, and at a really low level.

Laura Chappell showed off a lot of the new features in Wireshark 1.8. I even learned something you can type a color name (e.g. “bisque3”) into the color picker in the preferences. She also released the second edition of Wireshark Network Analysis. It’s even heavier than the first edition, which I learned first-hand.

I led one session this year, Ask The Experts. We ended up talking about ways to improve Wireshark and a few of the core developers and I discussed these ideas the next day.

We got logs of great feedback on the conference as well. Several people commented that we didn’t have as many devlopment-oriented sessions this year as we have in the past. Maybe we can add more next time.

Wireshark is a great and wondrous thing due to its community. The developers, users, educators, sponsors all play a big role in its development and evolution. I see small reminders of this every day but it becomes abundantly clear each year at Sharkfest.

Thanks to the attendees, presenters, and to the Riverbed events team for creating a wonderful experience. I can’t wait to see what next year’s Sharkfest has in store.

Wireshark and Pcap-ng

When Wireshark 1.8.0 is released in the next few months it will introduce two major features: the ability to capture from multiple interfaces at once and the ability to annotate packets. These features have been on the wishlist for years and they will make Wireshark much more useful. They both share dependency on pcap-ng.

Packet comment example

Packet comment example

Pcap-ng is Wireshark’s new default file format. It is more complex than its predecessor (pcap) but it’s also more flexible. Along with multiple interface types and annotations you can store host information, extended interface information, and much more. Wireshark has had basic support for pcap-ng for several years now and 1.8.0 will bring it to the forefront.

But there’s a catch. Suppose you sit down at a computer with Wireshark 1.7 or 1.8 installed. What file format will Wireshark use by default? Unfortunately the answer is “It depends.” If this is a fresh install of Wireshark on a new computer you’ll get pcap-ng files. If this is an upgrade from 1.6 or below you’ll get pcap files. If the preferences were changed or copied from another machine the default format will be affected as well.

There’s another catch. Suppose you’ve just saved a capture file and you want to read it using tcpdump, Cascade Pilot, Snort, or any of the dozens of other applications that use the classic pcap file format. What will happen? Again, it depends. If that application has been updated to support pcap-ng or if it’s using a recent version of libpcap it will probably work. Otherwise don’t hold your breath.

If you’re a Wireshark user you might want to try a recent build of Wireshark 1.7 to see the new features and new file format in action. If you’re a developer and your application reads pcap files you’re most likely in for some grief. For that I apologize. You should probably investigate adding pcap-ng support now before your users start complaining.

Despite the migration pains the switch to pcap-ng is long overdue and will make Wireshark more useful to more people.