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TCP/IP Transmission Control Protocol / Internet Protocol Rakhi Saxena Assistant Professor, Deshbandhu College, Delhi University

What is TCP/IP? ,[object Object],[object Object],[object Object]

History of TCP/IP ,[object Object],[object Object],[object Object]

Why TCP/IP is Popular? ,[object Object],[object Object],[object Object],[object Object],[object Object]

TCP/IP & OSI ,[object Object],[object Object],Physical Network Interface Data Link Layer Internet (IP) Network Transport (TCP) Transport Session Presentation Application Application Corresponding TCP/IP Layer OSI Model Layer

Ethernet - Data-Link Layer ,[object Object],[object Object],[object Object]

Ethernet ,[object Object],[object Object],[object Object],[object Object],[object Object]

MAC address ,[object Object],[object Object],[object Object],[object Object]

Internet Protocol The IP in TCP/IP ,[object Object],[object Object],[object Object]

IP Datagrams ,[object Object],[object Object],[object Object],An IP packet is called a datagram

IP Addresses ,[object Object],[object Object],Rensselaer

IP Addresses ,[object Object],[object Object]

IP Addresses ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],IPv4 (version 4) IPv6 (version 6)

Network and Host IDs ,[object Object],[object Object],[object Object]

IP Addresses ,[object Object],[object Object],[object Object],[object Object],CS has a class B network

Host and Network Addresses ,[object Object],[object Object],[object Object]

Mapping IP Addresses to Hardware Addresses ,[object Object],[object Object],[object Object],[object Object]

ARP ,[object Object],[object Object],[object Object],Arp Arp!

ARP (cont.) ,[object Object],[object Object]

ARP conversation HEY - Everyone please listen! Will 128.213.1.5 please send me his/her Ethernet address? not me Hi Green! I’m 128.213.1.5, and my Ethernet address is 87:A2:15:35:02:C3

Services provided by IP ,[object Object],[object Object],[object Object],[object Object],[object Object]

IP-Layer Operation IP Data Link Physical IP Data Link Physical IP Data Link Physical Application TCP IP Data Link Physical X A B C Y X A B C Y Application TCP IP Data Link Physical TCP is end-to-end layer

Transport Layer & TCP/IP ,[object Object],[object Object],[object Object]

Process Layer Transport Layer Network Layer Data-Link Layer ICMP, ARP & RARP TCP UDP IP 802.3 Process Process

UDP User Datagram Protocol ,[object Object],[object Object],[object Object],[object Object]

Ports ,[object Object],[object Object],[object Object]

Ports Host A Host B Process Process Process Process Process Process

UDP ,[object Object],[object Object],[object Object],[object Object],The term datagram is also used to describe the unit of transfer of UDP!

TCP Transmission Control Protocol ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Connection-Oriented ,[object Object],[object Object],[object Object]

Reliable ,[object Object],[object Object],Reliable does not mean that things don't go wrong, it means that we find out when things go wrong.

Byte Stream ,[object Object],[object Object],Somebody needs to do this since IP is delivering all the data, it's just that the application layer doesn't need to do this!

Full Duplex ,[object Object],[object Object]

TCP Ports ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Addressing in TCP/IP ,[object Object],[object Object],[object Object],[object Object],NOTE: TCP/IP is a protocol suite that includes IP, TCP and UDP.

TCP/IP Summary ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

OSI and Protocol Stack OSI: Open Systems Interconnect Link Layer : includes device driver and network interface card Network Layer : handles the movement of packets, i.e. Routing Transport Layer : provides a reliable flow of data between two hosts Application Layer : handles the details of the particular application OSI Model TCP/IP Hierarchy Protocols 7 th Application Layer 6 th Presentation Layer 5 th Session Layer 4 th Transport Layer 3 rd Network Layer 2 nd Link Layer 1 st Physical Layer Application Layer Transport Layer Network Layer Link Layer

TCP vs. UDP ,[object Object],[object Object],[object Object],[object Object]

Hmmmmm. TCP or UDP ? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

TCP Connection Establishment ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Why is a two-Way Handshake not enough? When aida initiates the data transfer (starting with SeqNo=15322112355) , mng will reject all data. Will be discarded as a duplicate SYN 

T wo-Army Problem Red army Red army Blue army

T wo-Army Problem So how many acks of acks are enough??

C onnection Teardown Connection close is treated as two separate “close’s” of each simplex connection

Sockets ,[object Object],[object Object],[object Object],[object Object]

Packet Exchange for TCP Connection socket() socket() bind() listen() connect() write() read() read() write() Data reply, ack Data request ack of reply close() close() SYN j SYN k, ack j+1 ack k+1 FIN M ack M+1 FIN N ack N+1 CLIENT SERVER accept()

netstat –n Lists all active sockets with the address/port number pair

netstat –r Displays the routing table

netstat –s Displays network statistics

ping sends a test packet to a given address and reports the round trip time

traceroute discovers the route from a source to a destination

TCP/IP Hacks and Attacks ,[object Object],[object Object]

Denial of Service Attacks ,[object Object],[object Object],[object Object],[object Object],[object Object]

Early DOS attacks ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

TCP SYN Flood client server SYN RQST SYN ACK Spoofed SYN RQST zombie victim Waiting buffer overflows Zombies SYN ACK

Distributed Denial of Service Zombies on innocent computers Server-level DDoS attacks Infrastructure-level DDoS attacks Bandwidth-level DDoS attacks

Spoofing X Y Z Mr. Z is that you? Yes I’m here!

ARP Cache Poisoning IP -> 192.168.51.36 MAC -> 00:00:00:BB:BB:BB Internal ARP Cache 192.168.51.35 – 00:00:00:CC:CC:CC System B IP -> 192.168.51.35 MAC -> 00:00:00:AA:AA:AA Internal ARP Cache 192.168.51.36 – 00:00:00:CC:CC:CC System A IP -> 192.168.51.37 MAC -> 00:00:00:CC:CC:CC Internal ARP Cache 192.168.51.36 – 00:00:00:BB:BB:BB 192.168.51.35 – 00:00:00:AA:AA:AA Attacker 192.168.51.36 is at 00:00:00:CC:CC:CC 192.168.51.35 is at 00:00:00:CC:CC:CC

More DoS attacks Continuous requests for a heavy computational dynamic page HTTP SQL/Application server attack Source and destination IP addresses are the same causing the response to loop TCP SYN Land Local IP address hijack Middleman attack ARP ARP Redirect

ACL – Access Control List ,[object Object],[object Object],[object Object],[object Object],[object Object]

References ,[object Object],[object Object],[object Object],[object Object]

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