Networking

When working with Docker containers on complex networks, you often need to add static routes so containers can reach networks that aren’t directly connected to their default gateway. This becomes especially important when using macvlan network drivers where containers get their own IP addresses on your physical network. I’ve just released drouter, a lightweight systemd service that solves this problem by automatically injecting routes into Docker containers based on simple labels. The Problem Consider this scenario: you’re using a macvlan network driver so your containers get real IP addresses on your network (say 192.168.1.0/24). Your router is at 192.168.1.1, but you have additional internal subnets like 10.0.0.0/8 that are reachable through a different gateway at 192.168.1.254. ...

Adtran 411 Security Audit Adtran produces equipment for fiber ISPs. I was provided an Adtran 411 by my current ISP for Internet access and decided to take a deep look into it. Hardware The Adtran 411 is a small GPON fiber ONT (Optical Network Terminal) designed to give symmetrical gigabit fiber Internet to SOHO users. It connects to the ISP via a GPON uplink and provides the user a normal ethernet RJ-45 connector to plug their router into and a RJ-11 port for a landline to be tunneled over VOIP. ...

Tunneling WireGuard over TLS using SNI Domain Fronting There are numerous ways to get unrestricted egress on a restricted network. Here I will demonstrate how to use socat to tunnel a UDP connection over a TLS tunnel with a faked SNI domain in order to bypass network restrictions. This technique works on a restricted network that allows outbound TLS traffic to at least a single domain, but only checks the domain in the TLS Client Hello SNI field, and not the destination IP address. I have found this to be a common setup on many captive portal or restricted networks making use of a DPI firewall to block all other network traffic. ...

When creating a socket unless manually specified, the OS will automatically determine the source address to use. However, the OS’s default choice may not always be desired. Source Address Selection allows for influencing the sources address chosen by the OS. What is Source Address Selection? When a host with multiple routable IP addresses sends a packet to another host, it needs to determine which of its local addresses to use as the source “from” address. ...

When running a network with its own ASN, you will likely end up spending some time working with BGP. Knowing how your peer networks connect can help with your own network planning. BGP.Tools is a service that maps out different networks and the routes between them by having networks opt to provide bgp.tools with a BGP session sharing their exportable routes. This guide will walk you through setting up a BGP.Tools session with a Mikrotik router running RouterOS 7. ...

An opkg repository that builds Tailscale combined packages for OpenWrt devices, specifically providing a backport of Tailscale for OpenWrt 19.07. The project addresses the lack of official Tailscale packages for older OpenWrt versions by providing a flexible build system that generates installable packages across multiple hardware architectures. The repository includes automated build scripts that create opkg feed and package files, allowing users to easily install and configure Tailscale on their OpenWrt 19.07 devices. This enables secure mesh networking capabilities on legacy router firmware, making it simple to connect older OpenWrt devices to a Tailscale network for remote access and site-to-site connectivity.

This post outlines a security assessment of the new Sena Wifi Adapter I performed last summer for fun. With the world on lock-down due to COVID-19, I spent a lot of time last summer escaping the city going on motorcycle rides through the mountains and forests surrounding the bay area. It’s the perfect social distance activity because if you get within 6ft of someone you are likely to crash. One of my favorite motorcycle accessories is my Sena headset. It allows me to listen to navigation or music from my phone over Bluetooth while riding, and talk to other riders in my group. ...

A Go library and SOCKS5 proxy server that enables egress traffic from multiple IP addresses within a subnet. Stargate randomly distributes network connections across different IP addresses to avoid rate-limiting and provide load balancing across available IP ranges. The tool works best with subnets directly routed to the host and is particularly powerful for IPv6 subnet utilization. It supports both TCP CONNECT and UDP ASSOCIATE protocols and provides both a standalone proxy tool and a Go library for programmatic random IP networking. Requires specific network routing configuration and primarily supports Linux and FreeBSD platforms due to freebind networking capabilities.

This is the blog version of my DEFCON 26 talk Lost and Found Certificates: dealing with residual certificates for pre-owned domains, which I co-presented with Dylan Ayrey. You can learn more about BygoneSSL and see a demo at insecure.design. The Problem A Certificate can outlive the ownership of a domain. If the domain is then re-registered by someone else, this leaves with the first owner with a valid SSL certificate for the domain now owned by someone else. ...

Certgraph is a tool I’ve been developing to scan and graph the network of SSL certificate alternative names. It can be used to find other domains that belong to an organization that may be several orders removed and not always obvious. Background The idea for this project came about after examining the SSL certificate for XKCD.com. If you look closely at the screenshot below you will see that the SSL certificate used on XKCD.com is also valid for many of domains which have no relationship to XKCD or Randall Munroe. ...