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101 lines
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101 lines
3.1 KiB
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=========================
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Netflow Export & Analyses
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=========================
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.. image:: images/netflow_analyzer_insight.png
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:width: 100%
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Netflow is a monitoring feature, invented by Cisco, it is implemented in the FreeBSD
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kernel with ng_netflow (Netgraph). Since Netgraph is a kernel implementation it
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is very fast with little overhead compared to softflowd or pfflowd.
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While many monitoring solutions such as Nagios, Cacti and vnstat only capture traffic
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statistics, Netflow captures complete packet flows including source, destination
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IP and port number.
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OPNsense offers full support for exporting Netflow data to external collectors as
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well as a comprehensive Analyzer for on-the-box analysis and live monitoring.
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OPNsense is the only open source solution with a built-in Netflow analyzer integrated
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into its Graphical User Interface.
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------------------
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Supported Versions
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------------------
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OPNsense support both Netflow version 5 (IPv4) and version 9 (IPv4 & IPv6).
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--------------
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Netflow Basics
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--------------
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For analyzing the flow data it is important to understand the difference between
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ingress and egress traffic.
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Ingress
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-------
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Traffic to or coming from the firewall.
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Egress
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------
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Traffic passing trough the firewall.
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Ingress + Egress = Double flow count
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------------------------------------
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When enabling both ingress and egress, traffic gets counted double due to Network
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Address Translation as all packets going to the WAN coming from the LAN pass the
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Network translation of the firewall therefor also creating an ingress flow.
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If you are not interested in ingress traffic then OPNsense offers the option to
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filter this traffic. When utilizing a proxy on the same device its important to
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capture the ingress flows as well, otherwise all proxy traffic won't be visible.
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Downside is of course that all traffic not passing the proxy will we counted twice
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due to the mentioned NAT effect.
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----------------
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Netflow Exporter
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----------------
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OPNsense Netflow Exporter supports multiple interfaces, filtering of ingress flows
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and multiple destinations including local capture for analysis by Insight (OPNsense
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Netflow Analyzer).
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.. image:: images/netflow_exporter.png
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:width: 100%
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--------------------------
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Netflow Analyzer - Insight
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--------------------------
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OPNsense offers a full Netflow Analyzer with the following features:
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* Captures 5 detail levels
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* Last 2 hours, 30 second average
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* Last 8 hours, 5 minute averagae
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* Last week, 1 hour average
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* Last month, 24 hour average
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* Last year, 24 hour average
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* Graphical representation of flows (stacked, stream and expanded)
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* Top usage per interface, both ips and ports.
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* Full in/out traffic in packets and bytes
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* Detailed view with date selection and port/ip filter (up to 2 months)
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* Data export to csv for offline analysis
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* Selectable Detail Level
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* Selectable Resolution
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* Selectable Dat range
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.. image:: images/netflow_insight_details.png
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-------------
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Configuration
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-------------
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Setup Netflow Exporter
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----------------------
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See :doc:`/manual/how-tos/netflow_exporter`
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Setup Insight
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-------------
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See :doc:`/manual/how-tos/insight`
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