NETRESEC Network Security Blog - Tag : CIDR

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NetworkMiner 2.8 Released

NetworkMiner 2.8

I am happy to announce the release of NetworkMiner 2.8 today! This new version comes with an improved user interface, better parsing of IEC-104 traffic and decapsulation of CAPWAP traffic. The professional edition of NetworkMiner additionally adds port-independent detection of SMTP and SOCKS traffic, which enables extraction of emails and tunneled traffic even when non-standard ports are used.

User Interface Improvements

The first thing you see when starting NetworkMiner is the Hosts tab, which now has been updated to include a filter text box. This text box can be used to filter the displayed hosts based on the property fields they contain. By entering “Android” into the filter box NetworkMiner will show only the hosts having a property containing the string “Android”, for example in the OS classification or User-Agent string. Other properties you might find useful to filter on are hostname, JA3 hash and MAC address. If you’re running NetworkMiner Professional then you’ll also be able to filter on Country thanks to the MaxMind GeoLite2 feature included in the Pro edition.

NetworkMiner with Hosts filter Android

It’s now also possible to copy text from most tabs in NetworkMiner with Ctrl+C or by right-clicking and selecting “Copy selected rows”. A maximum of 10 rows can be copied at a time using the free version of NetworkMiner, while the Professional version allows all rows to be copied in one go.

The content based file type identification introduced in NetworkMiner 2.7 has been improved to also differentiate between EXE and DLL files as of version 2.8.

Matanbuchus malware download in NetworkMiner
Malicious AutoIt binary extracted from network traffic by NetworkMiner

IEC 60870-5-104

NetworkMiner’s parser for the SCADA protocol IEC 60870-5-104 (IEC-104) has been significantly improved in version 2.8. NetworkMiner now supports more IEC-104 commands and the commands are presented on the Parameters tab in a clearer way than before.

IEC-104 traffic in NetworkMiner

Image: IEC-104 commands sent by the Industroyer2 malware

I’m also proud to announce that NetworkMiner 2.8 now extracts files transferred over the IEC-104 protocol. More details about that particular feature is available in our IEC-104 File Transfer Extraction blog post.

CAPWAP Decapsulation

NetworkMiner 2.8 can read IEEE 802.11 packets inside CAPWAP tunnels between WLAN Controllers and Access Points. This feature allows WiFi traffic to be analyzed without having to capture packets in the air.

Reading PCAP from a Named Pipe

NetworkMiner previously allowed packets to be read from PacketCache over a named pipe. This feature has been upgraded to allow a PCAP stream to be read from any named pipe, not just from PacketCache. Here’s an example showing how to capture packets from localhost for 10 seconds with RawCap and make those packets available via a named pipe called “RawCap”:

RawCap.exe -s 10 \\.\pipe\RawCap

RawCap will start capturing packets once a PCAP reader connects to the “RawCap” named pipe, which now can be done with NetworkMiner by clicking “Read from Named Pipe” on the File menu.

Read PCAP from Named Pipe

Bug Fixes

NetworkMiner previously produced incorrect JA3S signatures for TLS servers if they sent Session ID values in Server Hello messages or listed only one supported TLS version using the Supported Versions extension. These bugs have now been fixed in NetworkMiner 2.8.

NetworkMiner’s live sniffing feature has been improved to better handle huge packets caused by Large Send Offload (LSO). NetworkMiner previously crashed with an error message saying that the received packet was “larger than the internal message buffer” when attempting to capture a too large packet.

TCP sessions occasionally didn’t show up in NetworkMiner’s Sessions tab previously if the application layer protocol was unknown. This bug has now been fixed in version 2.8.

New Features in NetworkMiner Professional

NetworkMiner Professional includes a feature for port independent protocol detection of protocols like FTP, HTTP, IRC, Meterpreter, SSH and TLS, which enables extraction of artifacts from those protocols even though the service is running on a non-standard port. This new release adds two additional protocols to the collection of identified protocols, namely SMTP and SOCKS. This allows analysts to extract emails from spam runs sent to ports other than 25 or 587, as well as to see what goes on inside covert SOCKS tunnels running on non-standard ports.

SMTP usernames and passwords extracted from SMTP traffic

Image: SMTP credentials extracted from spam run to non-standard SMTP port

In addition to allowing hosts to be filtered using string and regex matching, NetworkMiner Professional also allows the discovered hosts to be filtered on IP address using CIDR notation, such as “” or “”.

NetworkMiner with CIDR filter

Image: NetworkMiner Professional with CIDR filter

Here are some IPv4 and IPv6 CIDR filters that you might find useful:

  • = IPv4 multicast (224/4 is also supported)
  • = IPv4 loopback (127/8 is also supported)
  • fe80::/10 = IPv6 link-local addresses
  • ff00::/8 = IPv6 multicast
  • = IPv4 hosts (0/0 is also supported)
  • 0::/0 = IPv6 hosts


We’d like to thank René Perraux, Matt Smith and Anand Kumar Singh for reporting bugs that have been fixed in this new release.

Upgrading to Version 2.8

Users who have purchased NetworkMiner Professional can download a free update to version 2.8 from our customer portal, or use the “Check for Updates” feature from NetworkMiner's Help menu. Those who instead prefer to use the free and open source version can grab the latest version of NetworkMiner from the official NetworkMiner page.

Posted by Erik Hjelmvik on Monday, 02 January 2023 08:00:00 (UTC/GMT)

Tags: #NetworkMiner#IEC-104#SMTP#SOCKS#PIPI#CIDR

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CapLoader 1.6 Released

CapLoader 1.6

CapLoader is designed to simplify complex tasks, such as digging through gigabytes of PCAP data looking for traffic that sticks out or shouldn’t be there. Improved usability has therefore been the primary goal, when developing CapLoader 1.6, in order to help our users do their work even more efficiently than before.

Some of the new features in CapLoader 1.6 are:

  • Context aware selection and filter suggestions when right-clicking a flow, session or host.
  • Support for IPv6 addresses in the BPF syntax for Input Filter as well as Display Filter.
  • Flows that are inactive for more than 60 minutes are considered closed. This timeout is configurable in Tools > Settings.

Latency Measurements

CapLoader 1.6 also introduces a new column in the Flows tab labeled “Initial_RTT”, which shows the Round Trip Time (RTT) measured during the start of a session. The RTT is defined as “the time it takes for a signal to be sent plus the time it takes for an acknowledgment of that signal to be received”. RTT is often called “ping time” because the ping utility computes the RTT by sending ICMP echo requests and measuring the delay until a reply is received.

Initial RTT in CapLoader Flows Tab
Image: CapLoader 1.6 showing ICMP and TCP round trip times.

But using a PCAP file to measure the RTT between two hosts isn’t as straight forward as one might think. One complicating factor is that the PCAP might be generated by the client, server or by any device in between. If we know that the sniffing point is at the client then things are simple, because we can then use the delta-time between an ICMP echo request and the returning ICMP echo response as RTT. In lack of ping traffic the same thing can be achieved with TCP by measuring the time between a SYN and the returning SYN+ACK packet. However, consider the situation when the sniffer is located somewhere between the client and server. The previously mentioned method would then ignore the latency between the client and sniffer, the delta-time will therefore only show the RTT between the sniffer and the server.

This problem is best solved by calculating the Initial RTT (iRTT) as the delta-time between the SYN packet and the final ACK packet in a TCP three-way handshake, as shown here:

Initial Round Trip Time in PCAP Explained
Image: Initial RTT is the total time of the black/bold packet traversal paths.

Jasper Bongertz does a great job of explaining why and how to use the iRTT in his blog post “Determining TCP Initial Round Trip Time”, so I will not cover it in any more detail here. However, keep in mind that iRTT can only be calculated this way for TCP sessions. CapLoader therefore falls back on measuring the delta time between the first packet in each direction when it comes to transport protocols like UDP and ICMP.

Exclusive Features Not Available in the Free Trail

The new features mentioned so far are all available in the free 30 day CapLoader trial, which can be downloaded from our CapLoader product page (no registration required). But we’ve also added features that are only available in the commercial/professional edition of CapLoader. One such exclusive feature is the matching of hostnames against the Cisco Umbrella top 1 million domain list. CapLoader already had a feature for matching domain names against the Alexa top 1 million list, so the addition of the Umbrella list might seem redundant. But it’s actually not, the two lists are compiled using different data sources and therefore complement each other (see our blog post “Domain Whitelist Benchmark: Alexa vs Umbrella” for more details). Also, the Umbrella list contains subdomains (such as, and while the Alexa list only contains main domains (like “”). CapLoader can therefore do more fine-granular domain matching with the Umbrella list (requiring a full match of the Umbrella domain), while the Alexa list enables a more rough “catch ‘em all” approach (allowing * to be matched).

CapLoader Hosts tab with ASN, Alexa and Umbrella details

CapLoader 1.6 also comes with an ASN lookup feature, which presents the autonomous system number (ASN) and organization name for IPv4 and IPv6 addresses in a PCAP file (see image above). The ASN lookup is built using the GeoLite database created by MaxMind. The information gained from the MaxMind ASN database is also used to provide intelligent display filter CIDR suggestions in the context menu that pops up when right-clicking a flow, service or host.

CapLoader Flows tab with context menu for Apply as Display Filter
Image: Context menu suggests Display Filter BPF “net” based on the server IP in the right-clicked flow.

Users who have previously purchased a license for CapLoader can download a free update to version 1.6 from our customer portal.

Credits and T-shirts

We’d like to thank Christian Reusch for suggesting the Initial RTT feature and Daan from the Dutch Ministry of Defence for suggesting the ASN lookup feature. We’d also like to thank David Billa, Ran Tohar Braun and Stephen Bell for discovering and reporting bugs in CapLoader which now have been fixed. These three guys have received a “PCAP or it didn’t happen” t-shirt as promised in our Bug Bounty Program.

Got a t-shirt for crashing CapLoader

If you too wanna express your view of outlandish cyber attack claims without evidence, then please feel free to send us your bug reports and get rewarded with a “PCAP or it didn’t happen” t-shirt!

Posted by Erik Hjelmvik on Monday, 09 October 2017 08:12:00 (UTC/GMT)

Tags: #CapLoader#free#IPv6#BPF#CIDR#PCAP#Umbrella#Alexa

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BPF is your Friend

CapLoader BPF

CapLoader comes with support for Berkeley Packet Filter (BPF), which makes it possible to filter network traffic based on IP addresses, protocols and port numbers without using external tools. Being able to filter captured network traffic is crucial when analyzing large sets of PCAP files as well as in order to hunt down compromised hosts with Rinse Repeat Intrusion Detection.

There are two ways to apply filters with BPF in CapLoader; you can either apply an input filter before loading your PCAPs, or you can apply a display filter after the capture files have been loaded.

Input Filter

The fastest way to filter a large set of PCAP files with CapLoader is to enter an Input Filter before loading the capture files. Having an input filter will speed up the loading time significantly, since CapLoader will not need to analyze packets and flows that don't match the BPF syntax. The downside is that you will need to know beforehand what filter you want to use. In order to apply a changed input filter you need to reload the loaded PCAP files (pressing F5 will do this for you).

CapLoader with input filter “tcp port 443”
Image: CapLoader with input filter “tcp port 443”

Display Filter

CapLoader supports display filters in order to allow filters to be changed on the fly, without having to reload the PCAP files. As the name implies, display filters affect what flows/services/hosts that are displayed in CapLoader. A changed display filter does not require the dataset to be reloaded, but it does require the GUI to update the visible flows. This GUI update will be somewhat slower compared to when setting an input filter.

CapLoader with display filter “host”
Image: CapLoader with display filter “host”

BPF Syntax

CapLoader's BPF implementation does not support the full BPF syntax. In fact, only the most central primitives are implemented, which are:

host <IP address>Flows to or from the specified IPv4 or IPv6 address
net <CIDR> Flows to or from the specified IP network, uses CIDR notation
port <port>Flows to or from the specified port number
ip6Flows using IPv6 addresses
ipFlows using IPv4 addresses
tcpTCP flows
udpUDP flows
sctpSCTP flows

More complex filter expressions can be built up by using the words and, or, not and parentheses to combine primitives. Here are some examples:

  • host and udp port 53
  • net and port 80
  • (port 80 or port 443) and not host

For all boolean algebra geeks out there we can confirm that our BPF implementation gives and precedence over or, which means that the last example above would give a different result if the parentheses were removed.

Keeping it Short

Steve McCanne gave a keynote presentation at SharkFest 2011, where he talked about how he created BPF. Steve's work was guided by Van Jacobson, who challenged him to make the BPF syntax human friendly rather than requiring the user to type a clunky filtering syntax. We've adopted this thinking and therefore allow filters like these:

    Flows to or from IP address Translates to “ip host”

  • 128.3/16
    Flows to or from the network. Translates to “ip net”

  • port 53
    Flows to or from TCP, UDP or SCTP port 53.

Try it for Free!

We've made the BPF implementation available even in the free version of CapLoader. You don't need to register to get the free version; just download, extract and run. The tool is portable, so you won't even have to install it. Visit to grab a copy and start filtering!

UPDATE 2016-05-23

With the release of CapLoader 1.4 it is now possible to apply Display Filters not only to the Flows tab, but also to the Services and Hosts tab.

Posted by Erik Hjelmvik on Monday, 30 November 2015 08:15:00 (UTC/GMT)

Tags: #CapLoader#BPF#PCAP#Berkeley Packet Filter#filter#IP#port#CIDR

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