More netblob

selected/http_to_phy.md

@@ -133,3 +133,84 @@ Good learning resources for ARP:
 - TLS/SSL
 - Inspection and Testing Tools: tcpdump, wireshark, netcat and more
 - HTTP/2, HTTP/3
+
+
+## NET RAMBLE
+
+physical cables -- bits on wire / optics
+BGP -- Major Routing Hub to Major Routing Hub
+https://blog.benjojo.co.uk/post/bgp-battleships
+
+IP Distribution via IANA / ICANN
+-- blocks of IPv4 addresses auctioned to autonomous systems / organizations, who communication routing tables for blocks via BGP
+
+TTL / congestion control / TCP_NODELAY vs TCP_QUICKACK / TCP_CORK
+https://news.ycombinator.com/item?id=9048947
+
+DNS -- Domain Name Registrars who own TLDs (ex: .com, .org, .io)
+https://www.iana.org/domains/root/db
+https://messwithdns.net/
+https://wizardzines.com/zines/dns/
+https://jvns.ca/blog/2022/05/10/pages-that-didn-t-make-it-into--how-dns-works-/
+
+Switching -- on the Ethernet / MAC level, layer 2, VLANs can happen here
+<ETHERNET><><ETHERNET>
+Spanning Tree Protocol -- solves ARPSTORMs
+
+Link speed negotiation
+
+(intel) NUC with two (usb) NICs -- VMs that would tag traffic with VLAN.
+Ethernet packet tagged with VLAN 1, 
+
+| 1 1 1 1 1 1 1 2 | | 2i 2o |
+|               2 | |  NUC  |
+|               2 | |       |
+
+layer 2 ethernet -- hamachi / layer 3 ip -- openvpn
+
+Router in bridge mode -- Router A <=====> Router B
+
+Hubs are layer 1
+Switches are layer 2
+Routers are layer 3
+
+Home "router" is a router / switch combo
+
+Network Topology -- this is mostly outside my wheelhouse; infiniband/optics?
+
+"crossover cable"
+A            B
+TX ---\/--- TX
+RX ---/\--- RX
+
+"standard cable"
+A            B
+TX -------- TX
+RX -------- RX
+
+
+Switch maintains an ethernet routing table, uses mac addresses to determine which ports need to be routed to other ports
+
+TTL -- preventing packets from hopping forever on layer 3 connections, ICMP is a totally separate thing
+ICMP -- https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol
+
+SEND CHEESEBURGER TO GOOGLE
+A -> HR -> ISP -> | | | | -> GOOGLE
+subnet 192.168.1.X
+HR -> ISP | DESTINATION UNREACHABLE {ICMP 3} | TIME EXCEEDED {ICMP 11} TTL Expires
+Blocking ICMP is messy, be careful!
+
+https://en.wikipedia.org/wiki/Black_hole_(networking)
+PING sends ICMP | TTL
+traceroute {ICMP 30} tells each router on the chain to send back a response, they don't have to, they can just send through.
+`traceroute bad.horse`
+
+Network Tomography -- Mapping networks by gathering a bunch of timing data sending packets between nodes
+https://en.wikipedia.org/wiki/Network_tomography
+
+DHCP is automatic IP handouts
+But also, it tells you where your mail server is, how to get fortune cookies, and is a source of fun vulnerabilities
+
+TLS 1.2/1.3
+https://tls12.ulfheim.net/
+bearSSL