Protocols and TCP/IP Vocabulary
What is the valid range of a Class A network address?
1-126
Trap
Alerts sent by SNMP agents
Code bits
Control functions used to set up and terminate a session
Port 25
SMTP, TCP
Process/Application Layer Protocols
Telnet, FTP, TFTP, NFS, SMTP, LDP, X Window, SNMP, DNS, DHCP/BootP
Port 23
Telnet, TCP
Line Printer Daemon (LPD)
designed for printer sharing, along with the Line Printer (LPR) program, allows print jobs to be spooled and sent to the network's printers using TCP/IP
What is the Class A private IP address space?
10.0.0.0 through 10.255.255.255
What is the Class B private IP address space?
172.16.0.0 through 172.31.255.255
What is the Class C address range in decimal and in binary?
192-223, 110xxxxx
What is the Class C private IP address space?
192.168.0.0 through 192.168.255.255
Destination IP
32-bit IP address of the station this packet is destined for
IP Address
32-bit logical numeric identifier assigned to each machine on an IP network
Octet
8 bits
Byte
8 bits (with parity)
Reserved
Always set to zero
Process/Application layer
Application, Presentation, and Session layers
Header checksum
Cyclic redundancy check (CRC) on header only
Port 53
DNS, TCP & UDP
Network Access layer
Data Link and Physical layers
Acknowledgment number
Defines which TCP octet is expected next
ICMP events and messages
Destination Unreachable, Buffer Full, Hops, Ping, Traceroute,
Hops
Each IP datagram is allotted a certain number of routers, called hops, to pass through. If it reaches its limit of hops before arriving at its destination, the last router to receive that datagram deletes it. The executioner router then uses ICMP to send an obituary message, informing the sending machine of the demise of its datagram
Port 21
FTP, TCP
Header Length
HLEN in 32-bit words
Port 80
HTTP, TCP
Port 443
HTTPS, TCP
Data
Handed down to the TCP protocol at the Transport layer
What layer of the DoD model is equivalent to the Transport layer of the OSI model?
Host-to-Host
Version
IP Version number
Source IP
IP address of sending station
Internet Layer Protocols
Internet Protocol (IP), Internet Control Message Protocol (ICMP), Address Resolution Protocol (ARP), Reverse Address Resolution Protocol (RARP), Proxy ARP
Time to Live
Kills packets when time expires
Total Length
Length of of the packet
What is the 127.0.0.1 address used for?
Loopback or diagnostics
Options
May be 0 or a multiple of 32 bits
Internet layer
Network layer
Port 119
News, UDP
Port 110
POP3, UDP
Protocol
Port of upper-layer protocol (TCP is port 6 or UDP is port 17 [hex])
DoD Model
Process/Application layer, Host-to-Host layer, Internet layer, Network Access layer 0,0,1,1,1,2,0,2011-01-07 00:07
Fragment offset
Provides fragmentation and reassembly if the packet is too large to put in a frame
Sequence number
Puts the data back in the correct order or retransmits missing or damaged data, a process called sequencing
Port 161
SNMP, UDP
UDP Segment
Source Port, Destination Port, Length, Checksum, Data
TCP Header
Source Port, Destination Port, Sequence Number, Acknowledgment Number, Header Number, Reserved, Code Bits, Window, Checksum, Urgent, Options, Data
Flags
Specifies whether fragmentation should occur
Port 6 (hex)
TCP 1,0,0,0,0,1,0,2011-01-12 09:51
Port 69
TFTP, UDP
Header length
The number of 32-bit words in the TCP header. This indicates where the data begins.
Source port
The port number of the application on the host sending the data
Destination port
The port number of the application requested on the destination host
Proxy Address Resolution Protocol (Proxy ARP)
The technique in which one host, usually a router, answers ARP requests intended for another machine. By "faking" its identity, the router accepts responsibility for routing packets to the "real" destination. Proxy ARP can help machines on a subnet reach remote subnets without the need to configure routing or a default gateway.
Urgent
The urgent pointer points to the sequence number of the octet following the urgent data
Window
The window size the sender is willing to accept, in octets
Internet Control Message Protocol (ICMP)
They are encapsulated within IP datagrams
Internet Control Message Protocol (ICMP)
They can provide hosts with information about network problems
Host-to-Host Layer Protocols
Transmission Control Protocol (TCP) & User Datagram Protocol (UDP)
Host-to-Host layer
Transport layer
How do you find the network address from a listed IP address?
Turn all host bits off
How do you find the broadcast address from a listed IP address?
Turn all host bits on
Port 17 (hex)
UDP
Identification
Unique IP-packet value
Data
Upper-layer data
Options
Used for network testing, debugging, security, and more
Ping (Packet Internet Groper)
Used to check the physical and logical connectivity of machines on an internetwork
Traceroute
Used to discover the path a packet takes as it traverses an internetwork
Address Resolution Protocol (ARP)
Used to find the hardware address from a known IP address
IP Header
Version, Header Length, Priority & Type, Total Length, Identification, Flags, Fragment Offset, Time to Live, Protocol, Header Checksum, Source IP, Destination IP, Options, Data
Destination Unreachable
When a router can't send an IP datagram any further
Buffer Full
When a router's memory buffer for receiving incoming datagrams is full
Baseline
a report delimiting the operational traits of a healthy network
Broadcast Address
address used by applications and hosts to send information to all nodes on a network
Network File System (NFS)
allows two different types of file systems to interoperate
Simple Network Management Protocol (SNMP)
collects and manipulates network information,
DHCP
connectionless, uses User Datagram Protocol (UDP)
Port Numbers below 1024
considered well-known port numbers dynamically assigned by the source host
Checksum
cyclic redundancy check (CRC) checks the header and data fields
Internet Protocol (IP)
decides where a packet is to be sent next, choosing the best path using a routing table
Reverse Address Resolution Protocol (RARP)
discovers the identity of the IP address for diskless machines by sending out a packet that includes its MAC address
UDP
fast, connectionless, unreliable
File Transfer Protocol (FTP)
file transfer between 2 machines, a protocol and a program, accesses directories and files, uses Telnet for login, cannot execute remote programs
TCP
full-duplex, connection-oriented, reliable, and accurate
Bootstrap Protocol (BootP)
gives an IP address to a host but the host's hardware address must be entered manually in a BootP table; used to send 'diskless workstations' their boot image
Priority & Type
how the datagram should be handled
TCP
lots of overhead
Internet Control Message Protocol (ICMP)
management protocol and messaging service provider for IP
IP Address
may be depicted in dotted-decimal, hex, or binary
Network Address/Number
numerical identifier for a remote network; uniquely identifies each network
Bit
one digit, 1 or 0
Dynamic Host Configuration Protocol (DHCP)
provides an IP Address, Subnet Mask, Domain Name, Default Gateway, DNS, WINS
Domain Name Service (DNS)
resolves hostnames/fully qualified domain name (FQDN)
TCP
segments and sequences information, waits for acknowledgments over the virtual circuit
Trivial File Transfer Protocol (TFTP)
stripped-down version of FTP, no directory-browsing abilities, uses smaller blocks of data, no authentication
Telnet
terminal emulation - allows a user on a remote client machine, called the Telnet client, to access the resources of another machine, the Telnet server
Internet Protocol (IP)
the Internet layer; the other protocols found here merely exist to support it
X Window
to allow a program, called a client, to run on one computer and have it display things through a window server on another computer
Node Address
uniquely identifies each machine on a network
Port Numbers 1024 and above
used by the upper layers to set up sessions with other hosts, used by TCP to use as source and destination addresses
Simple Mail Transfer Protocol (SMTP)
uses a spooled, or queued, method of mail delivery, used to send mail (POP3 is used to receive mail)
