BreachBytes

Most of my posts on BreachBytes are about using flow data, primarily NetFlow, for network security, incident response and network forensics on enterprise networks. I also tend to get rather technical most of the time. For this post I want to take a step back and answer the following question: what’s the big deal about network flow data? Let me try to answer this question in a single sentence:

“Network flow data, which can be generated by all enterprise routers, provides security analysts with real-time, long-term network visibility that can be used to prevent data leakage, defend against the insider threat and enhance incident response effectiveness.”

Key Points:

1. Generated by all enterprise routers: The technology is in place, your network can generate flow data in some form.
2. Real-time: Flow reporting can be near-real time depending on configuration.
3. Network visibility: Most enterprises are essentially blind to their internal network (the Soft Gooey Center — good in candy, bad in networks).
4. Long-term: Disk is cheap and flows are small, while still providing adequate information for a variety of network security tasks.

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If you have the money ($75K+) and a big data center moving a lot of data, Cisco’s Nexus 7000 series switch offers wickedly fast processing power and a lot of compelling security features. Hopefully this signals an increased interest in network security by the switch vendors.

Running NX-OS version 4.0, the Nexus 7000 switch supports a wide variety of useful security features you’d expect from a high-end switch: 802.1x, RADIUS, MAC-based ACLs for policy enforcement, etc. More important to us at BreachBytes is the native hardware support for NetFlow. I commented Monday on the fact that sFlow is generally more prevalent in switches than NetFlow, however Cisco seems to be challenging this assertion with their OS upgrade and supporting products like the Nexus 7000.

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In a previous post I gave a rundown of various software tools for collecting NetFlow data for use in network security incident response. NetFlow is pervasive in routers but another technology, sFlow, is nearly as prevalent in routers and can be collected from switches — an arena that NetFlow does not play in very much as of yet. sFlow is a packet sampling technology and can provide a depth of network visibility — a key component of network forensic and incident response — even beyond what NetFlow can offer. For more information on sFlow check out sflow.org.

There is not as much activity in free software with sFlow compared to NetFlow, however InMon has a great suite of tools that can help enterprises leverage sFlow data from routers and switches. Their sFlow Agent software can sniff packets off a network interface card and convert them into sFlow packets if you do not have a sFlow enabled switch or router but want to test what sFlow can bring to the table.

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