Can IPv4 Networks Be Compromised via IPv6?

The Fox-IT International Blog recently published an article on how IPv4 networks can be compromised via IPv6. The attack vector relies on the default IPv6 configuration in the Windows operating system to spoof DNS replies by acting as a malicious DNS server to redirect traffic to an attacker-specified endpoint. The Windows Proxy Auto Discovery (WPAD) feature can also be exploited in order to relay credentials and authenticate to various services within the network, using a tool called called mitm6 created by Fox-IT.

Fox-IT is recommending that IPv6 is disabled when it is not being used, as disabling Proxy Auto Detection. This of course means that Windows-based hosts are unable to switch preference to IPv6 when it is available (which all versions since Windows Vista will do), and that IPv6 would need to be explicitly re-enabled on hosts.

The article makes some important points, but IPv4 and IPv6 are fundamentally incompatible on a wire level and it needs to be understood they can’t communicate with each other except through translation devices. There are a number of known issues (including this one) with the security of automatic configuration mechanisms running on Local Area Networks, both under IPv6 and IPv4, but these require physical access to Continue reading

SYN packet handling in the wild

SYN packet handling in the wild

Here at Cloudflare, we have a lot of experience of operating servers on the wild Internet. But we are always improving our mastery of this black art. On this very blog we have touched on multiple dark corners of the Internet protocols: like understanding FIN-WAIT-2 or receive buffer tuning.

SYN packet handling in the wild
CC BY 2.0 image by Isaí Moreno

One subject hasn't had enough attention though - SYN floods. We use Linux and it turns out that SYN packet handling in Linux is truly complex. In this post we'll shine some light on this subject.

The tale of two queues

SYN packet handling in the wild

First we must understand that each bound socket, in the "LISTENING" TCP state has two separate queues:

  • The SYN Queue
  • The Accept Queue

In the literature these queues are often given other names such as "reqsk_queue", "ACK backlog", "listen backlog" or even "TCP backlog", but I'll stick to the names above to avoid confusion.

SYN Queue

The SYN Queue stores inbound SYN packets[1] (specifically: struct inet_request_sock). It's responsible for sending out SYN+ACK packets and retrying them on timeout. On Linux the number of retries is configured with:

$ sysctl net.ipv4.tcp_synack_retries
net.ipv4.tcp_synack_retries = 5

The docs describe Continue reading

IoT security needs a white knight

Thanks to the Mirai botnet attacks, few people in the world of tech need a reminder that IoT devices remain a serious threat to enterprise networks. Still, more than a year after the botnet made headlines worldwide, IoT security remains mostly an idea, rather than a reality.Such is the scope of the problem that Frost and Sullivan IoT research director Dilip Sarangan argues for governmental intervention. Sarangan says that, because the responsibility for IoT security is diffused across device manufacturers, network providers, software developers and many others, it’s difficult for the industry to make progress on all-encompassing standards.To read this article in full, please click here

Facebook and Amazon are causing a memory shortage

If you’ve noticed a considerable increase in the price of memory in the last few months, you can thank (or blame) Amazon, Facebook, and Google. The explosion in growth among hyperscale data centers is great if you are a supplier of components to these companies, not so great if you are buying those same components.According to DRAMeXchange, a division of market researcher TrendForce, the price of server DRAM will continue to rise as the supply remains tight in the first quarter of this year. The server DRAM market has seen tight supply since the third quarter of last year due to massive construction projects by the data center market, especially the hyperscale data centers, data centers that are bigger than a football field.To read this article in full, please click here

Facebook and Amazon are causing a memory shortage

If you’ve noticed a considerable increase in the price of memory in the last few months, you can thank (or blame) Amazon, Facebook, and Google. The explosion in growth among hyperscale data centers is great if you are a supplier of components to these companies, not so great if you are buying those same components.According to DRAMeXchange, a division of market researcher TrendForce, the price of server DRAM will continue to rise as the supply remains tight in the first quarter of this year. The server DRAM market has seen tight supply since the third quarter of last year due to massive construction projects by the data center market, especially the hyperscale data centers, data centers that are bigger than a football field.To read this article in full, please click here

Meltdown and Its Networking Equivalents

One of my readers sent me this question:

Do you have any thoughts on this meltdown HPTI thing? How does a hardware issue/feature become a software vulnerability? Hasn't there always been an appropriate level of separation between kernel and user space?

There’s always been privilege-level separation between kernel and user space, but not the address space separation - kernel has been permanently mapped into the high-end addresses of user space (but not visible from the user-space code on systems that had decent virtual memory management hardware) since the days of OS/360, CP/M and VAX/VMS (RSX-11M was an exception since it ran on 16-bit CPU architecture and its designers wanted to support programs up to 64K byte in size).

Read more ...

NSX-T: OpenAPI and SDKs

Nowadays everything is about automation. Organizations are moving away from the traditional static infrastructure to full automation and here the need of NSX is significant. There are many use-cases for NSX, but the common in all of them is that they all need to be automated.

VMware is investing heavenly for different tools to ease the automation aspect of NSX but in order to take full advantage of it one need to understand what happens under the hood. It is also important if someone wants to build their own custom automation tool or CMP (Cloud Management Platform). Many existing solutions like Openstack, Kubernetes, vRO and so on automate NSX-T using different plugins. In fact, those plugins are sending REST API calls to NSX Manager in order to automate logical topology CRUD(Create, Read, Update, Delete) operations.

Based on our experience we decided that NSX-T APIs will be based on JSON format following OpenAPI standard. The use of Open APIs is to enable third party developers to build applications and services around NSX-T by standardising on how REST APIs are described. This means one can use standard tools like Swagger to read and use those APIs. Below is a quick example from my Mac on Continue reading

Cisco Now Reselling Docker Enterprise Edition

Today we are excited to announce the expansion of our partnership with the availability of Docker Enterprise Edition (EE), our container management platform on the Cisco Global Price List (GPL) and the release of the latest Cisco Validated Design (CVD):

Cisco UCS Infrastructure with Contiv and Docker Enterprise Edition for Container Management

Cisco

Now customers can purchase Docker EE directly from Cisco and their joint resellers to jumpstart their new year’s resolution for a more modern application architecture, reduce IT costs and redirect saving to innovation projects.  And with our latest CVD for Cisco UCS compute infrastructure with secure container networking fabric, Contiv,  we’ve provided a roadmap on how to get started so customers and partners can gain a faster, more reliable and predictable implementation of Docker EE.

For enterprises looking to use Docker’s container management platform but not sure where to start, we can help you take the first step. The Migrating Traditional Applications (MTA) Program, designed for IT operations teams, helps enterprises modernize existing legacy .NET Windows or Java Linux applications without modifying source code or re-architecting the application in just five days with Docker and Cisco Advanced Services. The results have been incredible, with customers saving over 50% on infrastructure costs and Continue reading

NSX-T: Routing where you need it (Part 2, North-South Routing)

In the first part of this blog series, NSX-T: Routing where you need it (Part 1), I discussed how East-West (E-W) routing is completely distributed on NSX-T and how routing is done by the Distributed Router (DR) running as a kernel module in each hypervisor. 

In this post, I will explain how North-South (N-S) routing is done in NSX-T and we will also look at the ECMP topologies. This N-S routing is provided by the centralized component of logical router, also known as Service Router. Before we get into the N-S routing or packet walk, let’s define Service Router.

Service Router (SR)

Whenever a service which cannot be distributed is enabled on a Logical Router, a Service Router (SR) is instantiated. There are some services today on NSX-T which are not distributed such as:

1) Connectivity to physical infrastructure
2) NAT
3) DHCP server
4) MetaData Proxy
5) Edge Firewall
6) Load Balancer

Let’s take a look at one of these services (connectivity to physical devices) and see why a centralized routing component makes sense for running this service. Connectivity to physical topology is intended to exchange routing information from NSX domain to external networks (DC, Campus or Continue reading

Domain Name System Security Extensions (DNSSEC) Cheat Sheet Released

Here is the Cheat Sheet for DNSSEC. Recently vulnerabilities in the DNS were discovered that allow an attacker to hijack this process of looking some one up or looking a site up on the Internet using their name. The purpose of the attack is to take control of the session to, for example, send the user to the hijacker's own deceptive web site for account and password collection.

These vulnerabilities have increased interest in introducing a technology called DNS Security Extensions (DNSSEC) to secure this part of the Internet's infrastructure.

If you found a bug or want new content to be added, email me!

Click here to download DNSSEC Cheat Sheet

Wi-Fi Alliance announces WPA3 to secure modern networks

The Consumer Electronics Show (CES) is an odd place to announce an enterprise product, but the Wi-Fi Alliance used the massive trade show — which has more or less taken over where Comdex left off — to announce a major upgrade to Wi-Fi security.The alliance announced the Wi-Fi Protected Access 3 (WPA3), a new standard of Wi-Fi security that greatly increases the security capabilities of the wireless standard. WPA2, which is the current standard in wireless security, has been around for 14 years, so this is way overdue.To read this article in full, please click here

Wi-Fi Alliance announces WPA3 to secure modern networks

The Consumer Electronics Show (CES) is an odd place to announce an enterprise product, but the Wi-Fi Alliance used the massive trade show — which has more or less taken over where Comdex left off — to announce a major upgrade to Wi-Fi security.The alliance announced the Wi-Fi Protected Access 3 (WPA3), a new standard of Wi-Fi security that greatly increases the security capabilities of the wireless standard. WPA2, which is the current standard in wireless security, has been around for 14 years, so this is way overdue.To read this article in full, please click here

Wi-Fi Alliance announces WPA3 to secure modern networks

The Consumer Electronics Show (CES) is an odd place to announce an enterprise product, but the Wi-Fi Alliance used the massive trade show — which has more or less taken over where Comdex left off — to announce a major upgrade to Wi-Fi security.The alliance announced the Wi-Fi Protected Access 3 (WPA3), a new standard of Wi-Fi security that greatly increases the security capabilities of the wireless standard. WPA2, which is the current standard in wireless security, has been around for 14 years, so this is way overdue.To read this article in full, please click here

New developments in the net neutrality debate

Democrats in the USA haven’t given up on net neutrality since the FCC voted to repeal the 2015 Open Internet Order in December.

Senator Markey, a Democrat from Massachusetts, has put forward a bill that would use the Congressional Review Act (CRA) to reverse the Federal Communications Commission’s (FCC) decision. The CRA allows lawmakers 60 legislative days after the FCC submits its regulations to Congress to take action.

That bill now has the support of more than 40 Senators, including Senator Susan Collins (R-Maine), its first Republican supporter.

Senator Markey needs 52 votes to get the bill passed in the Senate, which is unlikely given that Republicans remain in control of both chambers of Congress. Nevertheless, Democrats see value in forcing a vote on the bill ahead of the 2018 midterm elections. Polls indicate that 83 per cent of Americans support keeping the FCC’s net neutrality rules.

If the bill fails to move forward, Congress may pursue a legislative solution – a bill that would codify net neutrality rules into law, rather than a reversal of the FCC’s decision. In fact, the Republicans are possibly signaling an appetite to come to a legislative solution to this issue. Regardless of Continue reading