What’s new in MACsec: setting up MACsec using wpa_supplicant and (optionally) NetworkManager

A few months ago, on this blog, we talked about MACsec. In this post, I want to introduce the work we’ve done since then. Since that work revolves around methods to configure MACsec, this will also act as a guide to configure it by two methods: wpa_supplicant alone, or NetworkManager with wpa_supplicant.

If you read the previous MACsec post, you probably thought that this whole business of generating keys and creating “secure associations” isn’t very convenient, especially given that you then have to monitor your associations and generate new keys manually. And you’re right: it’s not.

Besides, if you run RHEL or Fedora, you’re probably used to configuring your network with NetworkManager, so you would expect to be able to configure MACsec with NetworkManager as well. We’re going to describe this below. First, let’s go a little bit behind the scenes.

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The need for speed and the kernel datapath – recent improvements in UDP packets processing

Networking hardware is becoming crazily fast, 10Gbs NICs are entry-level for server h/w, 100Gbs cards are increasingly popular and 200Gbs are already surfacing. While the Linux kernel is striving to cope with such speeds with large packets and all kind of aggregation, ISPs are requesting much more demanding workload with NFV and line rate packet processing even for 64 bytes packets.

Is everything lost and are we all doomed to rely on some kernel bypass solution? Possibly, but let’s first inspect what is really the current status for packet processing in the kernel data path, with a perspective look at the relevant history and the recent improvements.

We will focus on UDP packets reception: UDP flood is a common tool to stress the networking stack allowing arbitrary small packets and defeating packet aggregation (GRO), in place for other protocols.

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Open vSwitch: Overview of 802.1ad (QinQ) Support

Open vSwitch (OVS) recently gained support for 802.1ad (QinQ). It can be used as a lightweight alternative to tunnel technologies such as; VXLAN, GENEVE, GRE. A key advantage of QinQ is that it can make use of hardware offload features common in network interface cards (NICs). Only newer NICs support hardware offload for VXLAN and GENEVE. QinQ also incurs less frame processing and has a smaller encapsulation overhead.

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MACsec: a different solution to encrypt network traffic

MACsec is an IEEE standard for security in wired ethernet LANs. This blog , will give an overview of what MACsec is, how it differs from other security standards, and present some ideas about how it can be used.

  • MACsec is a Layer 2 protocol that relies on GCM-AES-128 to offer integrity and confidentiality, and operates over ethernet.
  • It can secure all traffic within a LAN, including DHCP and ARP, as well as traffic from higher layer protocols.
  • It is an  extension to 802.1X provides secure key exchange and mutual authentication for MACsec nodes.
  • IPsec (a Layer 3 security protocol) and TLS (a Layer 4 security protocol) offer different guarantees and can be a better fit, depending on the use case.

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Testing your software stack without root privileges using cwrap

by Jakub Hrozek and Andreas Schneider

Software testing is already a hard business. It gets even harder if you need to test software that is networked, requires custom users on the system or resolve DNS queries.

Consider software such as a file server — it needs to listen for incoming connections on a certain port, often a privileged one in case of well-known protocols. The file server also requires the ability to switch to different user accounts and act on their behalf to create files owned by these users. Finally, a client of this hypothetical file server might want predefined SRV records to be present in DNS for autodiscovery to work properly. All these cases should be tested on every build.

And it gets even harder if your unit tests can’t run as the root user to set up the environment. The use case of testing the full stack, including network, users or DNS with only regular user privileges is exactly what the cwrap.org project is aiming to solve.

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