Posts from 2020

  • How to make an ARM virtual machine (armhf/aarch64)

    Dec 26, 2020
    Sysadmin
    6 minutes
    qt.ax/avm

    Update (2022-03-19): I wrote about a new way to create an ARM virtual machine that’s simpler and handles kernel updates properly. I highly suggest you follow those instructions instead, unless you are building a chroot.

    I noticed that very few people seem to know how to create a full ARM virtual machine, so I decided to create a quick guide.

    This tutorial will use aarch64 and Debian as examples, but the same methodology should work for 32-bit ARM and other distributions. The instructions can also be adapted to create a simple chroot.

    (Read more...)

  • Run a Linux Program on a Different Network Interface

    Jan 3, 2020
    Sysadmin
    4 minutes
    qt.ax/rdni

    Sometimes, you have multiple Internet connections, whether physical or virtual, and you want a few programs to access the Internet through one connection without making it the default gateway. For example, if you want a program to connect to the Internet through a VPN, but without forcing the entire system’s traffic through the VPN as well.

    The traditional way to do this is with packet marking with iptables and an ip rule to force marked packets through a different routing table to send the traffic to the correct destination. However, as the source IP was selected before routing, an SNAT rule in iptables is required to change the source IP. This is ugly and clearly a hack.

    However, since around 2013, Linux has introduced networking namespaces, which can be managed via ip netns as part of the iproute2 package. We can easily exploit this feature to achieve the desired goal with minimal fuss.

    (Read more...)