Category Archives: Monitoring

Monitoring the local network, firewall statistics, temperature values, energy consumption, or whatever.

CPU Usage Increase FortiGate 100D -> 90D

A few weeks ago I swapped a FortiGate 100D firewall to a 90D firewall. The 100D was defective and needed to be replaced. Since the customer only has a 20 Mbps ISP connection, I thought that a FortiGate 90D would fit for the moment, since it has a firewall throughput of 3,5 Gbps, compared to the lower value of 2,5 Gbps from the 100D.

Indeed, it worked. However, the CPU usage increase was huge, almost related to the NGFW throughput. Here are some graphs:

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Using NetFlow with nProbe for ntopng

This blog post is about using NetFlow for sending network traffic statistics to an nProbe collector which forwards the flows to the network analyzer ntopng. It refers to my blog post about installing ntopng on a Linux machine. I am sending the NetFlow packets from a Palo Alto Networks firewall.

My current ntopng installation uses a dedicated monitoring ethernet port (mirror port) in order to “see” everything that happens in that net. This has the major disadvantage that it only gets packets from directly connected layer 2 networks and vlans. NetFlow on the other hand can be used to send traffic statistics from different locations to a NetFlow flow collector, in this case to the tool nProbe. This single flow collector can receive flows from different subnets and routers/firewalls and even VPN tunnel interfaces, etc. However, it turned out that the “real-time” functionalities of NetFlow are limited since it only refreshes flows every few seconds/bytes, but does not give a real-time look at the network. It should be used only for statistics but not for real-time troubleshooting.

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ntopng Installation

Some time ago I published a post introducing ntopng as an out-of-the-box network monitoring tool. I am running it on a Knoppix live Linux notebook with two network cards. However, I have a few customers that wanted a persistent installation of ntopng in their  environment. So this is a step-by-step tutorial on how to install ntopng on a Ubuntu server with at least two NICs.

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MRTG/Routers2: Template FortiGate

A few weeks ago I constructed an MRTG/Routers2 template for the Fortinet FortiGate firewalls. I am using it for monitoring the FortiGate from my MRTG/Routers2 server. With the basic MRTG tool “cfgmaker” all graphs for the interfaces are generated automatically. My template is an add-on that appends graphs for CPU, memory, and disk usage, as well as connections and VPN statistics. Furthermore, it implements the ping statistics graph and a “short summary”, which only shows the system relevant graphs.

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Out of the Box Network Analyzer “ntopng”

Some time ago I installed a new firewall at the customer’s site. Meanwhile the customer was interested in the flows that are traversing through the firewall right now. Oh. Good question. Of course it is easy to filter through log messages of firewalls, but theses logs are only for finished sessions. Yes, there are “session browsers” or the like on all firewalls, but they are not nice and handy to analyze the sessions in real-time.

The solution was to bring a network analyzer on a mirror port near to the firewall. I decided to use ntopng running on the live Linux distribution Knoppix. Great choice! An old notebook with two network adapters fits perfectly. A handful commands and you’re done:

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Logfile Parsing

While parsing logfiles on a Linux machine, several commands are useful in order to get the appropriate results, e.g., searching for concrete events in firewall logs.

In this post, I list a few standard parsing commands such as grep, sort, uniq, or wc. Furthermore, I present a few examples of these small tools. However, it’s all about try and error when building large command pipes. 😉

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MRTG/Routers2: Template Juniper SSG

Finally, this is how I am monitoring my Juniper ScreenOS SSG firewalls with MRTG/Routers2. Beside the interfaces (that can be built with cfgmaker) I am using my template in order to monitor the CPU & memory, count of sessions & VPNs, count of different kind of attacks, etc.

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MRTG/Routers2: Template Juniper SA/MAG

I am monitoring an (old) SA-2000 cluster of Juniper Secure Access devices with my MRTG/Routers2 system. With the JUNIPER-IVE-MIB I built the configuration file for that monitoring system. In this blog post, I show the graphs generated with MRTG/Routers2 and publish my cfg file as a template.

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MRTG/Routers2: Template Cisco ASA

I constructed a MRTG/Routers2 configuration template for the Cisco ASA firewall which consists the OIDs (graphs) for the interfaces, CPU, memory, VPNs, connections, ping times, and traceroute hop counts. With only four search-and-replace changes as well as a few further specifications, the whole SNMP monitoring for that firewall is configured.

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IPv4 vs. IPv6 Traffic Statistics on Routers

I am very interested in statistics about the usage of IPv6 on Internet routers and firewalls. The problem is, that most routers/firewalls do not have unique SNMP OIDs for IPv4 and IPv6 traffic, but only the normal incoming/outgoing packet counters per interface. Therefore I am using two independent ethernet ports and cables between my outer router and my first firewall, one for IPv4-only and the other one for IPv6-only traffic. Now I have independent statistics for each protocol and can combine them in one summary graph. (Though I know that this will never be a “best practice” solution…)

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Stromzähler mit S0-Schnittstelle vom Raspberry Pi auswerten

Endlich ist es soweit: Ich lese den Stromverbrauch von unserer Wohnung mit einem Raspberry Pi aus und lasse mir von meinem Monitoring Server (MRTG + Routers2) schöne Graphen malen. Hierfür verwende ich einen Stromzähler mit einer S0-Schnittstelle, welchen ich direkt in der Unterverteilung eingebaut habe. Die Impulse des “Smart Meters” wertet eine Interruptroutine am Pi aus. Der Monitoring Server wiederum fragt den Pi per SNMP ab. Viele kleine Schritte also, die ich in diesem Blogpost ausführlich erläutern möchte. Viel Spaß damit!

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Grep Commands for Cisco ASA Syslog Messages

In a basic environment with a Cisco ASA firewall I am logging everything to a syslog-ng server. As there aren’t any reporting tools installed, I am using grep to filter the huge amount of syslog messages in order to get the information I want to know. In this blog post I list a few greps for getting the interesting data.

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