REDIR - Unbound DNS for Adblock

This article introduces REDIR, aka "redirection module", an extension to Unbound DNS that I have developed for very quickly answering queries of blocked domains (ads, trackers, malware sites and etc) and requires little extra resources. For example, a fresh instance of Unbound with REDIR enabled occupies less than six Mbyte…

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User Space Bootstrap in EdgeRouter Firmware 2.0

BackgroundUbiquiti released firmware v2.0.0 for EdgeRouter models at the turn of 2019. FW 2.0 is based on Debian Stretch and has been in development for the past two years or so. Cavium models come with Linux kernel 4.9.y. ERX series come with kernel 4.14.…

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EDNS Client-Subnet

The problemA recursive DNS resolver such as Google Public DNS or your ISP's DNS server resolves domain names into IP addresses. Popular websites or services are usually hosted on Content Delivery Networks (CDN) where a domain name could resolve into different IP corresponding to servers in disperse locations. In such…

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CPU Hogging on EdgeRouter-X

I started running a public NTP server behind my ER-X recently. The server is part of NTP Pool Project and serves many clients over IPv6 only. At its peak, the load can reach about 1000 requests per second. In the extreme cases, it could go as high as 5000 requests…

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Benchmark USB Flash Drives on Routers

Update Jan 28, 2019: iozone-db.txt collects benchmark results submitted by folks. Thank you. I eventually made up my mind on the choice of single-board computers (SBC) that will assist and eventually replace the role of my Asus RT-AC56U as an always-on home server. It's not a Raspberry Pi. My…

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A Simple Tool to Test malloc Performance

I was porting this very interesting feature to an older Glibc version for ARMv7. I need a simple tool to gauge any performance boost (or drop for that matter). Surprisingly few information is available on this topic. I didn't search hard but most papers on malloc performance dating back to…

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