Intro. to Networks This lecture will consist Internet and Ethernet short history Layer model (ISO and IP) Routing and routers Linux routing table PPP short history and purpose PPP and Linux

Internet & Ethernet Brief history Internet ( – ARPANET (The Internet origin) 1969 – UNIX 1972 – Ethernet 1989 – WWW 1991 – Linux 1992 – Mosaic

Internet organization ISOC – IETF – IETF RFCs – IANA – IAB – W3C –

Other org. involve in Networks ISO – ITU – IEEE –

OSI layers via Internet layers OSI Physical Data link Network Transport Session Presentation Application IP Ethernet hardware Ethernet IP stack TCP/UDP stack IP applications

LAN MAC Addresses Registration through the IEEE. XX-XX-XX-XX-XX-XX Vendor register leading XX-XX-XX. Example: 3Com register A Example: a NIC made by 3Com A-0C-01-93

Making LAN We need 4 component to make LAN Cables NICs in the PCs or other (e.g. Printers) Hubs (Repeaters) Switches

Configure NIC Use hotplug. lspci, lspci -n PCI Vendor ID. (on the Internet) /lib/modules/ /kernel/drivers/net/ USB Cable, USB ADSL => USB NIC. lsmod ifconfig -a

IP v4 Address Class A /24 Class B /16 Class C /8 Class D Class E

IP Network and subnets A name for IP based LAN. IP Network – mask according to class. IP sub network have a smaller mask. Example: , is subnet class A.

Address Resolution Protocol RFC 826 Map LAN MAC into the IP address. Dynamic ARP. Manual ARP Static ARP.

Linux LAN ifconfig -a – See your interfaces arp -n – See the ARP table arp -s ip mac – Set ARP route -n ip - iproute2 tool

IP routing. Router Server B-1A-3C-B B3-1D-5E BA-13-BC BA-13-BC-13 Dst Src Dst MAC BA-13-BC-11 Src MAC B-1A-3C-B4

IP routing. Router Server B-1A-3C-B B3-1D-5E BA-13-BC BA-13-BC-13 Dst Src Dst MAC B3-1D-5E-87 Src MAC BA-13-BC-13

Routing table Default Gateway. Simple example: Destination Gateway Genmask Flags Metric Ref Use Iface U eth UG eth0

A real route RIP – RFC 1058, 1388, 1723 OSPF - RFC 2178 (v2) BGP - RFC 1771 (BGP-4) PIM – RFC 2362, 3973 OSI IS-IS IGRP, EIGRP – Cisco. Real routers are not just routers!

PPP Point to Point Protocol IP protocol for connecting PC over phone line. Use tty char device for transferring IP packets. RFC 1661, RFC 1662 (STD 51) HDLC ISO 3309

Why PPP? Phone lines. Authentication. Bandwidth and QoS control Dynamic client to ISP mapping. Easy configuration VPN. Compression option. Packets concatenating.

PPP structure LCP – Create the PPP link. PAP or CHAP authentication. HDLC – Octet/Bit stuffed framing

PPP over link layer PPPoE - RFC 2516 PPPoA – RFC 2364 MAC address or VP instead of phone line.

PPP over IP L2TP – RFC 2661, RFC 3931 (v3) PPTP – RFC 2637 Server IP instead of phone number. Two IP networks with one IP stack Need a more complicated routing. Possible to work L2TP over PPPoE.

PPP over IP routing Simple example: Destination Gateway Genmask Flags Metric Ref Use Iface UH ppp U eth UG ppp0

Linux PPP tools The PPP daemon PPTP client – works with the pppd. L2TP – status unknown. PPPoE PPPoA – kernel patch with ATM driver. Kernel PPP, PPPoE, PPPoA