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Learn through exercises how to setup and troubleshoot network design with transparent NAT. Understand ARP, gateways, and load balancing. Text in English.
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Exercises Network design and configuration (c) A. Mariën - Ubizen
Transparent NAT (c) A. Mariën - Ubizen
internet Before NAT WebServer 188.54.20.2 router firewall LAN HUB LAN HUB 10.20.0.0/16 188.54.20.0/24 (c) A. Mariën - Ubizen
internet After NAT: OK? “188.54.20.2” WebServer 10.20.0.2 router firewall LAN HUB LAN HUB 188.54.20.0/24 10.20.0.0/16 “188.54.20.2” 10.20.0.2 (c) A. Mariën - Ubizen
internet After NAT: Need ARP fix! “188.54.20.2” WebServer MACIF2 10.20.0.2 MACIF1 router firewall LAN HUB LAN HUB 188.54.20.0/24 10.20.0.0/16 MACIF1 = ARP(188.54.20.2) “188.54.20.2” 10.20.0.2 (c) A. Mariën - Ubizen
RFC 1027 • Using ARP to implement transparent subnet gateways • Describes transparent subnet division using ARP (c) A. Mariën - Ubizen
Before Machine C 10.4.5.2 MACC Machine A 10.4.5.1 MACA HUB Machine B 10.4.5.3 MACB Machine D 10.4.5.4 MACD (c) A. Mariën - Ubizen
After Machine C 10.4.5.2 MACC Machine A 10.4.5.1 MACA HUB MACgwright 10.4.5.254 gateway HUB Machine B 10.4.5.3 MACB Machine D 10.4.5.4 MACD MACgwleft 10.4.5.253 (c) A. Mariën - Ubizen
Gateway ARP • Left • Macgwleft = ARP(10.4.5.2) • Macgwleft = ARP(10.4.5.4) • Macgwleft = ARP(10.4.5.253) • Right • Macgwright = ARP(10.4.5.1) • Macgwright = ARP(10.4.5.3) • Macgwright = ARP(10.4.5.254) (c) A. Mariën - Ubizen
Gateway routes • Route to host 10.4.5.1 via 10.5.4.253 • Route to host 10.4.5.3 via 10.5.4.253 • Route to host 10.4.5.2 via 10.5.4.254 • Route to host 10.4.5.4 via 10.5.4.254 (c) A. Mariën - Ubizen
ARP for loadbalancing • N systems can handle same request • Use ARP proxy to provide loadbalancing (c) A. Mariën - Ubizen
Network card in promiscuous mode • What does it mean? • What does it imply? (c) A. Mariën - Ubizen