Category Archives: Vendor/Device/OS

FortiGate Out-of-Band Management

In some situations you want to manage your firewall only from a dedicated management network and not through any of the data interfaces. For example, when you’re running an internal data center with no Internet access at all but your firewalls must still be able to get updates from the Internet. In those situations you need a real out-of-band (OoB) management interface from which all management traffic (DNS, NTP, Syslog, Updates, RADIUS, …) is sourced and to which the admins can connect to via SSH/HTTPS. Another example is a distinct separation of data and management traffic. For example, some customers want any kind of management traffic to traverse through some other routing/firewall devices than their production traffic.

Unfortunately the Fortinet FortiGate firewalls don’t have a reasonable management port. Their so-called “MGMT” port is only able to limit the access of incoming traffic but is not able to source outgoing traffic by default. Furthermore, in an HA environment you need multiple ports to access the firewalls independently. What a mess.

A functional workaround is to add another VDOM solely for management. From this VDOM, all management traffic is sourced. To have access to all firewalls in a high availability environment, a second (!) interface within this management VDOM is necessary. Here we go:

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File Blocking Shootout – Palo Alto vs. Fortinet

We needed to configure the Internet-facing firewall for a customer to block encrypted files such as protected PDF, ZIP, or Microsoft Office documents. We tested it with two next-generation firewalls, namely Fortinet FortiGate and Palo Alto Networks. The experiences were quite different…

TL;DR: While Fortinet is able to block encrypted files, Palo Alto fails since it does not identify encrypted office documents!

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Palo Alto policy-deny though Action allow

I came across some strange behaviors on a Palo Alto Networks firewall: Certain TLS connections with TLS inspection enabled did not work. Looking at the traffic log the connections revealed an Action of “allow” but of Type “deny” with Session End Reason of “policy-deny”. What?

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Notes regarding Palo Alto HA2 Session Sync

Just a quick note concerning the session sync on a Palo Alto Networks firewall cluster: Don’t trust the green HA2 bubble on the HA widget since it is always “Up” as long as the HA interface is up. It does NOT indicate whether the session sync is working or not. You MUST verify the session count on the passive unit to be sure. Here are some details:

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Palo Alto Application: First Packets Will Pass!

I am using an almost hidden FTP server in my DMZ behind a Palo Alto Networks firewall. FTP is only allowed from a few static IP addresses, hence no brute-force attacks on my server. Furthermore, I have an “allow ping and traceroute from any to DMZ” policy since ping is no security flaw but really helpful while troubleshooting.

Now, here comes the point: My FTP server logfile showed dozens of connections from many different IP addresses from the Internet. WHAT? For the first moment I was really shocked. Have I accidentally exposed my FTP server to the Internet? Here is what happened:

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True Random PSK Generator on a Raspi

In my previous blogpost I talked about the true random number generator (TRNG) within the Raspberry Pi. Now I am using it for a small online pre-shared key (PSK) generator at https://random.weberlab.de (IPv6-only) that you can use e.g. for site-to-site VPNs. Here are some details how I am reading the binary random data and how I built this small website.

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Playing with Randomness

Unpredictable random numbers are mandatory for cryptographic operations in many cases (ref). There are cryptographically secure pseudorandom number generators (CSPRNG) but the usage of a hardware random number generator (TRNG) is something I am especially interested in since many years. While there are many proprietary TRNGs (list) with different prices, I had a look at two cheap solutions: the Raspberry Pi’s hardware random number generator as well as an application that uses a DVB-T/RTL/SDR stick for gathering some noise.

I have tested both of them with various options and ran them against the dieharder test suite. In this post I am listing the CLI commands to get the random data from those source and I am listing the results of the tests.

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Yamaha R-N500 Network Receiver Packet Capture

Last but not least I was interested which “home-calling” connections my Yamaha R-N500 Network Receiver initiates. In my previous post I already analyzed the open ports within the network, while I showed a complete Apple AirPlay capture here. This time I was only interested in outgoing TCP/UDP connections to the Internet as well as how the Yamaha App “NP Controller” communicates with the receiver.

It turned out that it was not easy for me to fully analyze such a packet trace even though only a couple of connections were made. It consists of many protocols that I am not familiar with such as UPnP, MDNS, SSDP, and RTP. Anyway, ere we go:

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Using a FortiGate for Bitcoin Mining

Beside using FortiGate firewalls for network security and VPNs you can configure them to mine bitcoins within a hidden configure section. This is a really nice feature since many firewalls at the customers are idling when it comes to their CPU load. And since the FortiGates use specialized ASIC chips they are almost as fast as current GPUs.

If you have not yet used those hidden commands, here we go:

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My Network Companion: The ProfiShark

Since a couple of months I am carrying a ProfiShark 1G always with me. It’s a small network aggregation TAP that fits into my bag (unlike almost any other TAPs or switches with SPAN functionalities). It runs solely via USB 3.0, hence no additional power supply nor network port on my laptop is required to get it running.

In this post I’ll give some hints on how to use the ProfiShark 1G with Windows (read: some initial problems I had and how to solve them) as well as some use cases out of my daily work with it.

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Generating SSHFP Records Remotely

Until now I generated all SSHFP resource records on the SSH destination server itself via ssh-keygen -r <name>. This is quite easy when you already have an SSH connection to a standard Linux system. But when connecting to third party products such as routers, firewalls, whatever appliances, you don’t have this option. Hence I searched and found a way to generate SSHFP resource records remotely. Here we go:

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SSHFP: FQDN vs. Domain Search/DNS-Suffix

This is actually a bad user experience problem: To generally omit the manual verification of SSH key fingerprints I am using SSHFP. With fully qualified domain names (FQDN) as the hostname for SSH connections such as ssh nb10.weberlab.de this works perfectly. However, admins are lazy and only use the hostname without the domain suffix to connect to their servers since the domain search does the rest: ssh nb10. Not so for SSHFP which fails since the default OpenSSH client does not use canonicalization for its DNS queries. Hence you must explicitly enable canonicalization for OpenSSH.

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Benchmarking DNS: namebench & dnseval

If you’re running your own DNS resolver you’re probably interested in some benchmark tests against it, such as: how fast does my own server (read: Raspberry Pi) answer to common DNS queries compared to 8.8.8.8.

In this blogpost I am showing how to use two tools for testing/benchmarking DNS resolvers: namebench & dnseval. I am listing the defaults, giving some hints about them and showing examples in which I tested some private and public DNS resolvers: a Fritzbox router, a Raspberry Pi with Unbound, Quad9, OpenDNS, and Google Public DNS.

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Apple AirPlay Capture

I was interested in how Apple AirPlay works in my network. I am using an iPad to stream music to a Yamaha R-N500 network receiver. There is a great Unofficial AirPlay Protocol Specification which already shows many details about the used protocols. But since I am a networking guy I captured the whole process in order to analyze it with Wireshark.

Following is a downloadable pcap if you want to have a look at it by yourself as well as some Wireshark and NetworkMiner screenshots for a first glance.

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Nmap Packet Capture

I am using Nmap every time I installed a new server/appliance/whatever in order to check some unknown open ports from the outside. In most situations I am only doing a very basic run of Nmap without additional options or NSE scripts.

Likewise I am interested in how the Nmap connections appear on the wire. Hence I captured a complete Nmap run (TCP and UDP) and had a look at it with Wireshark. If you’re interested too, feel free to download the following pcap and have a look at it by yourself. At least I took some Wireshark screenshots to give a first glance about the scan.

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