The Backend Engineering Show with Hussein Nasser

Cloudflare released a blog detailing a vulnerability that has been in their system for nearly two years. it is related to mTLS or mutual TLS and specifically client certificate revocation. I explore this in details 0:00 Intro 3:00 The Vulnerability 7:00 What happened? 8:50 Certificate Revocation 12:30 Rejecting certain endpoints 17:00 Certificate Authentication 20:30 Certificate serial number 24:0...

BGP (Border gateway protocol) withdrawals caused the Virgin media ISP customers to lose their Internet connection. I go into details on this video. 0:00 Intro 2:00 What happened? 4:11 How BGP works? 11:50 Version media withdrawals 15:00 Deep dive Fundamentals of Backend Engineering Design patterns udemy course (link redirects to udemy with coupon) https://backend.husseinnasser.com

GitHub Accidentally Exposed their SSH RSA Private key, this is the message you will get . @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY! Someone could be eavesdropping on you right now (man-in-the-middle attack)! It is a...

How Linus Tech Tips channel got Hacked In this short video we explain how was it possible for Linux to get hacked with cookies hijacking. 0:00 Intro 0:47 TLDR what happened 5:10 Cookies in Chrome 7:30 Cookies Hijacking 8:46 Session Tokens (Access/Refresh) 10:00 Remedies

Get my database engineering course https://database.husseinnasser.com In this video I do a deep dive in all locks obtained by postgres, I learned a lot while making this video and hope you enjoy it.  0:00 Intro  2:30 What are Locks?  5:30 Overview of Postgres Locks 9:10 Table-Level Locks 11:40 ACCESS EXCLUSIVE 17:40 ACCESS SHARE 19:00 ROW SHARE 20:15 ROW EXCLUSIVE 21:15 SHARE UPDATE EXCLUSIVE 23:3...

Pinterest moves to HTTP/3 on all their clients and edge CDNs this year. They witnessed interesting gains but not without good lesson learned. The main one was the mismatch of alt-svc vs DNS ttls. I cover this on the next episode of the backend engineering course. 0:00 Intro 2:00 Moving h2 to h3 through alt-svc 5:00 Why HTTP/3 6:00 HTTP/1 vs HTTP/2 9:00 TCP Head of Line blocking in HTTP/2 11:00 How...

On March 7 2023, Loom users started seeing each others data as a result of cookies getting leaked from the CDN. This loom security breach is really critical. Let us discuss   0:00 Intro 1:00 Why Cookies 2:00 How this happens 5:50 What caused it? 7:30 How Loom solved it? 8:20 Reading the RCA 10:30 Remedies

Discord engineering goes into details of how they migrated from Cassandra to ScyllaDB, improved the performance of their reads and writes and rearchitected their backend to support the new load. It is an interesting episode lets get into it 0:00 Intro 1:50 Relational vs Distributed 7:00 The Cassandra Troubles 11:00 SnowFlake vs UUID 14:30 B+Tree 19:20 B+Tree and SSDs 25:30 LSM Trees 31:00 Hot part...

Creating a listener on the backend application that accepts connections is simple. You listen on an address-port pair, connection attempts to that address and port will get added to an accept queue; The application accepts connections from the queue and start reading the data stream sent on the connection. However, what part of your application does the accepting and what part does the reading and...

The Alt-Svc header/frame is a capability that allows the server to adverse alternative services to the connected application available in protocols, ports or domains. It is available as a response header alt-svc and also as an HTTP/2 frame. Let us discuss this capability. 0:00 Intro 1:38 what is alt-svc? 5:30 uses of h3 in alt-svc 8:00 alt-svc header 10:00 Alt-svc header with 103 early hints 14:48...

Correction: Google is implementing the proposal originally submitted by researchers from Georgia institute of tech. I incorrectly said in the video that google is proposing this . Google is finally implementing a proposal from 2008 by researchers from Georgia institute of technology to make DNS cache poisoning . https://astrolavos.gatech.edu/articles/increased_dns_resistance.pdf https://datatracke...

https://dropbox.tech/infrastructure/increasing-magic-pocket-write-throughput-by-removing-our-ssd-cache-disks In this episode of the backend engineering show I’ll discuss how Dropbox improved their write through put by 20% by removing all their SSDs (yes I was surprised too). DropBox uses an SSD layer as a write-back cache with SMR drives as their backend persistent storage. They changed their mode...

The communication between backend applications and database systems always fascinated me. The protocols keep evolving and we are in constant search for an efficient protocol that best fit the workload of Backend-DB communication. In this episode of the backend engineering show I go through a blog written by  @PlanetScale  doing an experimentation of using HTTP/3 and HTTP/2 comparing it w...

Fundamentals of Database Engineering udemy course (link redirects to udemy with coupon) https://database.husseinnasser.com Shopify posted a blog on tips to for scalable payment system, one tip peeked my interest related to switching from UUID to ULID. I explore the reasoning behind this in this video. https://shopify.engineering/building-resilient-payment-systems 0:00 Intro 1:30 idempotency 6:30 U...

I’m a big believer that database systems share similar core fundamentals at their storage layer and understanding them allows one to compare different DBMS objectively. For example, How documents are stored in MongoDB is no different from how MySQL or PostgreSQL store rows. Everything goes to disk, the trick is to fetch what you need from disk efficiently with as fewer I/Os as possible, the rest i...

The User Interface/User Experience has great impact on the backend architecture and scalability. In this podcast I discuss three UI/UX that affected backend design and scalability. 0:00 Intro 1:40 UI vs UX 4:30 Google Chrome OmniBox 12:30 1 out of X Page 20:00 YouTube Notification Resources https://blog.apnic.net/2020/08/21/chromiums-impact-on-root-dns-traffic/ Fundamentals of Backend Engineering...

In this video I explain how DHCP work and how it updates DNS entries for new hosts joining the network. I'll also mention Zero Config 0:00 Intro 1:00 the Network configuration 6:00 Showing DHCP in Wireshark 6:30 DHCP Discover 14:40 DHCP Offer 19:00 DHCP Request 21:30 DHCP ACK 22:00 How DHCP Updates DNS 26:15 Zero Configuration (mDNS, Link-local) Resources Dhcp https://datatracker.ietf.org/doc/html...

Fundamentals of Backend Engineering Design patterns udemy course (link redirects to udemy with coupon) https://backend.husseinnasser.com Certificates provide a way to authenticate both the server and the client and are included as part of the TLS handshake. However, the certificates can be large because the full certificate chain is included in the handshake. The large certificates can go up to 10...

Two new vulnerabilities in openssl were discovered, we discuss them in this video https://www.openssl.org/news/secadv/20221101.txt

Google recent paper on protective load balancing in TCP attempts to improve packet drops and latency by making the host change the flow path using the IPv6 Flow label. The Linux kernels gets the PLB support in Linux 6.2 this December, let us discuss with this is.   

In this episode of the backend engineering show I go through an article I wrote discussing NodeJS Asynchronous I/O https://medium.com/@hnasr/when-nodejs-i-o-blocks-327f8a36fbd4 Learn the fundamentals of network engineering, get my udemy course https://network.husseinnasser.com Buy me a coffee if you liked this  https://www.buymeacoffee.com/hnasr 0:00 3:00 Part 1 Socket/IO 9:48 Part 2 File I/O...

Buy me a coffee if you liked this https://www.buymeacoffee.com/hnasr In this podcast I explain the NGINX internal process architecture, how NGINX spins up multiple processes per core, how each process is pinned to a CPU core for minimum context switching,  how NGINX accepts connections , parses requests and talks to the backend.   Get my introduction to NGINX udemy course  http...

Cloudflare identified several limitations in NGINX architecture and decided to write their own reverse proxy. 0:00 Intro 1:53 What NGINX is used for 3:37 NGINX Architecture 7:52 NGINX Limitations 17:12 Cloudflare Pingora Buy me a coffee if you liked this https://www.buymeacoffee.com/hnasr Fundamentals of Networking for Effective Backends udemy course (link redirects to udemy with coupon) https://n...

In this episode of the backend engineering show I discuss the evolution of multi-threading apps, their pros and cons and then I go through 5 threading model and how they interleave with backend connection management between the threads and requests handlings. Enjoy To learn more about networking fundamentals check out my udemy course Fundamentals of Networking for Effective Backends Head to https:...

Memcached is an in memory cache with one major feature be a transient cache. Memcached has a very simple design. It was originally designed to help with database load by storing the query result in memory to avoid further querying the database. By default it has no authentication, a simple text protocols, servers don’t talk to each other. This video discuss the architecture of the cache, design ch...