Haben Sie mal Netzwerkmitschnitte untersucht, ohne zu wissen, was genau Sie suchen? Mit Wireshark wird das leicht zu einer Odyssee: Das Analysewerkzeug filtert zwar fabelhaft, reagiert bei großen Datenmengen aber schnell zäh.
Was bei solchen Problemstellungen hilft ist: tshark! Ein Tool, mit welchem Sie auch große Packet Captures einfach anhand gängiger Kriterien durchforsten können.
Palo Alto firewalls have a nice packet capture feature. It enables you to capture packets as they traverse the firewall. While you might be familiar with the four stages that the Palo can capture (firewall, drop, transmit, receive), it’s sometimes hard to set the correct filter – especially when it comes to NAT scenarios. (At least it was hard for me…)
I am using the packet capture feature very often for scenarios in which the IP connections are in fact working (hence no problems at the tx/rx level nor on the security policy/profile) but where I want to verify certain details of the connection itself. I’m simply using the Palo as a capturing device here, similar to a SPAN port on a switch. (Yes, I’m aware of all disadvantages of not using a real TAP and a real capture device.) In the end, I want a single pcap which shows all relevant packets for a client-server connection, even if NAT is in place. Wireshark should be able to correlate the incoming/outgoing packets into a single TCP stream. Furthermore, I definitely want to use a filter to limit the amount of captured packets. This is how I’m doing it:
Continue reading Palo Packet Capture: Choosing the Right Filter
As we have just set up a TLS capable syslog server, let’s configure a Fortinet FortiGate firewall to send syslog messages via an encrypted channel (TLS). Let’s go:
As we have just set up a TLS capable syslog server, let’s configure a Palo Alto Networks firewall to send syslog messages via an encrypted channel. While it was quite straightforward to configure I ran into a couple of (unresolved) problems as I added and deleted some syslog servers and their certificates. Uhm.
Some years ago I wrote a blog post called “Basic syslog-ng Installation“. While I used it myself quite often in my labs or at the customers’ sites, it shows only basic UDP transport which is both unreliable and insecure. So, let’s have a look at a fresh installation of syslog-ng with TLS support for security reasons. However, TCP and UDP as transport are covered as well for the support of legacy systems.
Again and again, I am adding some protocol samples to the Ultimate PCAP. Just for reference. And because I can. ;D
This is a guest blog post by Erik Hjelmvik, an expert in network forensics and network security monitoring at NETRESEC.
PolarProxy is a transparent TLS proxy that outputs decrypted TLS traffic as PCAP files. PolarProxy doesn’t interfere with the tunnelled data in any way, it simply takes the incoming TLS stream, decrypts it, re-encrypts it and forwards it to the destination. Because of this PolarProxy can be used as a generic TLS decryption proxy for just about any protocol that uses TLS encryption, including HTTPS, HTTP/2, DoH, DoT, FTPS, SMTPS, IMAPS, POP3S and SIP-TLS.
PolarProxy is primarily designed for inspecting otherwise encrypted traffic from malware, such as botnets that use HTTPS for command-and-control of victim PCs. Other popular use cases for PolarProxy is to inspect encrypted traffic from IoT devices and other embedded products or to analyze otherwise encrypted traffic from mobile phones and tablets. The fact that PolarProxy exports the decrypted traffic in a decrypted format without any TLS headers also enables users to inspect the decrypted traffic with products that don’t support TLS decryption, such as intrusion detection and network forensics products like Suricata, Zeek and NetworkMiner.
I was missing a generic layer 4 ping in my toolbox. Initially searching for a mere TCP ping, I have found Nping which completely satisfies my needs and gives so much more. ;)
What’s a layer 4 ping, and why? –> A normal ping (= ICMP echo-request) reveals whether the destination IP address, that is: the mere server/VM, is up and running. That’s great for a layer 3 networker since routing to and from the destination is already working. However, it does NOT reveal whether or not a service at layer 4 (TCP or UDP) is up and running as well. That’s what a layer 4 ping is about: sending TCP SYNs to the port in question, waiting for a “SYN ACK” (port is listening) or “RST”/no reply (port is not available). Common use cases: Waiting for a service to start again after an upgrade, or waiting for new firewall policies (to allow or deny) a certain port.
I am constantly trying to add more protocols to the Ultimate PCAP. Hence I used some time in my (old) Cisco lab to configure and capture the following protocols: IS-IS, GLBP, and VRRP. And since Alexis La Goutte sent me some CAPWAP traffic, this protocol is also added. All packets are now found in another update of the Ultimate PCAP. Here are some details:
Continue reading Capturing – because I can: IS-IS, GLBP, VRRP
The other day I was searching for a trace file with a decent protocol mix that could be used to introduce a few colleagues to Wireshark. This brought me to Johannes Weber and his Ultimate PCAP.
To get a first impression of a trace file I used Wireshark’s protocol hierarchy – and boy, that’s a lot of protocols. This was not exactly what I was looking for: This single trace file holds snippets from 2014 to 2020 with a myriad of protocols and IP networks. Unfortunately, it’s nothing like the protocol mix found in a network analysis project.
Nevertheless, the trace file caught my interest as a long time Wireshark user. After nearly 20 years of network analysis, I had my own collection of traces with a few odd frames. To my big surprise, I had recorded a few protocols that are not yet part of the Ultimate PCAP.
So here is my small contribution to this collection:
Continue reading Adding some packets: RARP, SNAP, MPLS & More
An updated version of my Ultimate PCAP is available. It features some more network protocols that I will depict in this blog post. It’s getting more special since the most common protocols were already in there. ;)
Uh, I wasn’t aware of so many different printing protocols. Do you? While I was trying to solve a little printing problem I took a packet capture of three different printing variants over TCP/IP: Raw via TCP port 9100, LPD/LPR via TCP port 515, and Apple’s AirPrint which uses the Internet Printing Protocol IPP. As always, you can download this pcap and have a look at it by yourself.
I gave a session about IPv6 at SharkFest’19 EUROPE, the annual Wireshark developer and user community conference, named “IPv6 Crash Course: Understanding IPv6 as seen on the wire“. The talk is about the IPv6 basics, which are: IPv6 addresses & address assignment, link-layer address resolution, and ICMPv6. Tips for using Wireshark coloring rules and display filters round things up.
As I have not yet published the slides, here they are. Unfortunately, we were not able to record the session due to technical problems. Neither the video nor the audio. ;( Hence, here are only mere slides.
In the previous post, I released my Ultimate PCAP which includes every single pcap I had so far on my blog. But that’s not all: I have some packets in there that were not yet published up to now. That is, here are some more details about those (probably well-known) protocols. These are:
For the last couple of years, I captured many different network and upper-layer protocols and published the pcaps along with some information and Wireshark screenshots on this blog. However, it always takes me some time to find the correct pcap when I am searching for a concrete protocol example. There are way too many pcaps out there.
This is supposed to change now: