Hannes Mehnert
Sessions
TCP/IP is the most widely used protocol on the Internet for transmitting data. But how does it work in detail? This talk will explain the TCP protocol, from handshake over established to teardown in detail - and elaborate a bit on protocol adjustments over time and congestion control.
Whenever you enter a name into your computer, it resolves it to a numerical IP address. This resolution uses the Domain Name System (DNS), which is a hierarchical decentralised naming system used on the Internet. DNS is organised in a way that top-level domain (e.g. .com, .org) are delegated to registrars, which delegate subdomains (e.g. foo.com). This delegation is done as well via the DNS protocol via nameserver (NS) records. Since different types of data are kept in DNS, it can as well be seen as a distributed (and cached!) key-value store - which is fault-tolerant.
I will explain the basic usage of DNS, including stub and recursive resolver, server, various protocol extensions (zone transfer, dynamic updates, authentication, notifications, ...), privacy extensions (query path minimisation, DNS-over-TLS), provisioning let's encrypt certificates. I will talk about attacks (poisoning, amplification, ...) and implementation pitfalls (not get stuck in the recursive resolver). I implemented DNS with above mentioned extensions as minimized MirageOS unikernels over past years.