# Shoot yourself in the foot with iptables and kmod auto-loading

DevFeed: [Shoot yourself in the foot with iptables and kmod auto-loading](<https://devfeed.tech/articles/shoot-yourself-in-the-foot-with-iptables-and-kmod-auto-loading-2139.md>)

Original publisher: [Read original article](<https://developers.soundcloud.com/blog//shoot-yourself-in-the-foot-with-iptables-and-kmod-auto-loading>)

Published: 2012-08-14T00:00:00Z

Content type: article

Language: en

Sources: [SoundCloud Backstage Blog](<https://devfeed.tech/sources/soundcloud-backstage-blog.md>)

Topics: [Linux](<https://devfeed.tech/topics/linux.md>), [Kernel](<https://devfeed.tech/topics/kernel.md>), [networking](<https://devfeed.tech/topics/networking.md>), [nginx](<https://devfeed.tech/topics/nginx.md>), [Monitoring](<https://devfeed.tech/topics/monitoring.md>), [systems](<https://devfeed.tech/topics/systems.md>), [Ubuntu](<https://devfeed.tech/topics/ubuntu.md>)

Tags: [errors](<https://devfeed.tech/tags/errors.md>), [infrastructure](<https://devfeed.tech/tags/infrastructure.md>), [kernel](<https://devfeed.tech/tags/kernel.md>), [linux](<https://devfeed.tech/tags/linux.md>), [monitoring](<https://devfeed.tech/tags/monitoring.md>), [nginx](<https://devfeed.tech/tags/nginx.md>), [outage](<https://devfeed.tech/tags/outage.md>), [post-mortem](<https://devfeed.tech/tags/post-mortem.md>), [ubuntu](<https://devfeed.tech/tags/ubuntu.md>)

## AI overview

This postmortem explains how listing iptables rules caused Linux kernel modules to be auto-loaded through kmod. Loading connection tracking unexpectedly contributed to a SoundCloud outage affecting an L7 routing nginx instance and produced 503/504 errors. The article reproduces the behavior on Ubuntu and describes raising a system limit as a temporary mitigation.

## Source excerpt

As some of you might know, we had an outage yesterday. We believe that in every mistake there is something to learn from, so after each...