Chapter 9 - TCP/IP Applications Flashcards
What does TCP over IP include
HTTP
DHCP
POP
… 500 other terms over tcp/udp & ICMP over IP
Define a session
Any single communication between a computer and another computer
What happens when an URL is entered
TCP Three Way Handshake
1. A SYN packet is ent to the Web Server.
2. Assuming the server has recieved it returns a SYN,
ACK packet
3. Client sends ACK and requests web page
How is a session closed
Server sends FIN packet and Client sends ACK to close session
Explain how DHCP works
Ports 67 (server) and 68 (DHCP clients) Uses a connectionless packet, if server doesn't respond it sends again
What is NTP/SNTP used for
Ports 123
Used to synchronize the clocks of devices on a network
What is TFTP used for
Port 69
Enables you to tranfer files from one machine to another. Common to send files via LAN
What is ICMP used for
used bynetwork devices, includingrouters, to send error messages and operational information indicating. This is the protocol used by ping.
What is the ‘ping of death’
Malicious users will send malformed ping packets to a destination causing the computer to crash.. now a fixed issue
Define IGMP
Internet Group Management Protocol enables routers to communicate with hosts to determine a ‘group’ membership
Uses a particular multicast where those who wish to receive a particular multicast must tell their upstream router/switch they want to receive. They are then added to the IGMP group
How big is a port number
16 bit
What is the range of the well known port numbers
0 to 1023, reserved for specific TCP/IP applications
Define Ephemeral Port numbers and the range
1024-5000 (varies by OS) + 49512-65535
A number is generated at random within this range to be used as the Web clinet’s source port number
What are the important (3) ranges to remember
0-1023 = well known ports
1024-49151 = Registered ports
49512 - 65535 = Dynamic or Private ports
Define Socket/Endpoint
Terms for the session information (IP address and port number) stored on a single computer
Define Socket Parts / Endpoints
Terms for the connection data stored on two computers about the same connection
Define connection / session
Terms for the whole interconnection
What is a open port /listening port
A socket prepared to respond to any IP packets sent its way
How does one use the netstat switches
- a = all used ports
- n = raw port numbers & IP
- o = process ID
- b = name of process
Define XML
Extensible Markup Language provides the basic format for everything from RSS feeds to Office documentse
Define NNTP
Network Nets transfer Protocol used to access USENET
Port 119
Define USENET
in the early days of internet it was used to swap info, ideas, and files.
Define URL
Uniform resource locator
Define TLS
Transport Layer Security is being used as a replacement for SSL
What was Telnet used for
connecting to different mainframes outside the local network. Connect via the command line
What features does IMAP4 have
Enables you to search through messages on the email server to find specific keywords and select the messages you want to download onto your machine. Also implements folders.
Explain the use of FTP
Using port 21 (outbound) and 20 )(requests) for old active connections and 21 only for passive connections. Anonymous sites mean anyone can log on
What issue does FTP have with NAT
Port 20 won’t be initiated and NAT won’t know where to send the packet. Firewalls will see this as evil.
Passive connections will receive a random port number from server so they work with NAT
