Module 11: Transport layer services Flashcards
give an example of a server hosting web and file sharing services and how it distinguishes between these
if a server is offering web services and file sharing services then it needs to know which service a host requires if an incoming message is destined for port 80 then the server knows that this message is bound for a web server application and is placed in the appropriate cue to be processed
what are the port(s) and transport protocol(s) of
File Transfer Protcol (FTP)
this uses:
- port 20 TCP for data
- port 21 TCP for control
this uses:
- port 67 UDP - on the server
- port 68 UDP - on the client
what are the port(s) and transport protocol(s) of
Dynamic Host Configuration Protocol (DHCP)
this uses:
- port 69 UDP
what are the port(s) and transport protocol(s) of
Trivial File Transfer Protocol (TFTP)
this is an address that can locate a resources it includes:
- Protocol/scheme - HTTPS or other protocols such as FTP, SFTP, mailto, and NNTP
- Hostname - ww.example.com
- Path and file name - /author/book.html
- Fragment - #page155

what is a
Uniform Resource Identifier (URI)
and what 4 parts can it include
what are the port(s) and transport protocol(s) of
Internet Message Access Protocol (IMAP)
this uses:
- port 143 TCP
describe the
Uniform Resource Name (URN)
this only includes the namespace of the resource and does not include the protocol or fragment
describe
User Datagram Protocol (UDP)
this is known as a ‘best effort protocol’ and resides on the layer 4 (transport layer). this protocol is in contrast to TCP in that it does not ensure all messages are delivered by using acknowledgments.
instead a message is broken up and sent without care of if they are received or not
what is the
netstat
command used for
this is used to view all current connections and listening ports. it may also be usefull in revealing suspicious connections.
what are the port(s) and transport protocol(s) of
Secure Shell (SSH)
this uses:
- port 22 TCP
describe in six steps the process of sending a message with
Transmission Control Protocol (TCP)
- it receives a message from the application layer and breaks it up into what are called segments
- each segment is then given a sequence number
- a given number of segments are then sent to the lower layers to be delivered
- the sender then waits for an acknowledgment that all segments sent were recieved
- if an acknowledgment is received then the next block of segments are sent
- if an acknowledgment is not received after a given time then the sender assumes the segments were lost and resends them
- it receives a message from the application layer and breaks it up into what are called segments
- each segment is then given a sequence number
- a given number of segments are then sent to the lower layers to be delivered
- the sender then waits for an acknowledgment that all segments sent were recieved
- if an acknowledgment is received then the next block of segments are sent
- if an acknowledgment is not received after a given time then the sender assumes the segments were lost and resends them
describe in six steps the process of sending a message with
Transmission Control Protocol (TCP)
this is a combination of an IP address and a port
example
192.168.1.20:80
describe what a
socket
is
this identifies:
- the client and the application
- the server and the application/service
example
a client socket could look like
192.168.1.2:5274
a web servers socket might look like
192.168.1.20:80
what does a
socket identify
what is a
Uniform Resource Identifier (URI)
and what 4 parts can it include
this is an address that can locate a resources it includes:
- Protocol/scheme - HTTPS or other protocols such as FTP, SFTP, mailto, and NNTP
- Hostname - ww.example.com
- Path and file name - /author/book.html
- Fragment - #page155

what does a
socket identify
this identifies:
- the client and the application
- the server and the application/service
example
a client socket could look like
192.168.1.2:5274
a web servers socket might look like
192.168.1.20:80
describe what a
socket
is
this is a combination of an IP address and a port
example
192.168.1.20:80
often used as source ports these can be used by any application
there range run from 49152 through 65535
describe
private ports
and their range
these are assigned to one of the following:
- well known ports
- registered ports
- private ports
these are managed and maintained by the
Internet Corporation for Assigned Names and Numbers (ICANN)
what are the 3 categories that
port numbers
are assigned to and
who manages these assignments
this uses:
- port 143 TCP
what are the port(s) and transport protocol(s) of
Internet Message Access Protocol (IMAP)
this only includes the namespace of the resource and does not include the protocol or fragment
describe the
Uniform Resource Name (URN)
this uses:
- port 80 TCP
what are the port(s) and transport protocol(s) of
Hypertext Transfer Protocol (HTTP)
this uses:
- port 20 TCP for data
- port 21 TCP for control
what are the port(s) and transport protocol(s) of
File Transfer Protcol (FTP)
this is used to locate a portion or area of the document, such as a page
what is the
fragment
of a Uniform Resource Identifier (URI)
what are the port(s) and transport protocol(s) of
Telnet
this uses:
- port 23 TCP
the process is:
- the network layer knows the source port and destination port from the information given by the application layer
- each segment is then given a header which includes the source and destination port
- each segment is then encapsulated in an IP packet
describe in 3 steps how
segments are encapsulated into IP packets
describe
registered ports
and their range
these can be either source or destination ports and can be used by organisations to register an application such as IM or gaming
the range is from 1024 through 49151
what do
application layer services
such as HTTP, DNS, FTP, DHCP. decide
these will decide:
- how client and server will communicate
- what information client and server will communicate
- the transport layer protocol that will be used
describe in 3 steps how
segments are encapsulated into IP packets
the process is:
- the network layer knows the source port and destination port from the information given by the application layer
- each segment is then given a header which includes the source and destination port
- each segment is then encapsulated in an IP packet
this uses:
- port 53
- UDP - for client IP queries. (queries and replies are sent in one packet so if it is lost it can simply be asked for and retransmitted)
- TCP - for zone transfers - this is a DNS server sharing records with another DNS server
what are the port(s) and transport protocol(s) of
Domain Name Service (DNS)
this uses:
- port 161 UDP
what are the port(s) and transport protocol(s) of
Simple Network Management Protocol (SNMP)
describe what
Transmission Control Protocol (TCP)
is
this is a layer 4 (transport layer) protocol that is responsible for ensuring a message is delivered in full and reassembled correctly when received
what are the port(s) and transport protocol(s) of
Simple Network Management Protocol (SNMP)
this uses:
- port 161 UDP
what is the
fragment
of a Uniform Resource Identifier (URI)
this is used to locate a portion or area of the document, such as a page
what are the 3 categories that
port numbers
are assigned to and
who manages these assignments
these are assigned to one of the following:
- well known ports
- registered ports
- private ports
these are managed and maintained by the
Internet Corporation for Assigned Names and Numbers (ICANN)
what are the port(s) and transport protocol(s) of
Hypertext Transfer Protocol Secure (HTTPS)
this uses:
- port 443 TCP
this uses:
- port 22 TCP
what are the port(s) and transport protocol(s) of
Secure Shell (SSH)
- the receiver receives a block of segments and puts them in the correct order
- if all segments for that block are received and correct then it sends an acknowledment message back to the sender and waits for the next block of segments
describe in 2 steps the process of
receiving a message via
Transmission Control Protocol (TCP)
these are destination ports that are associated with common network applications such as HTTP or SSH
there range is from 1 to 1023
describe the
well known ports
and there range
what is a
socket pair
and what can it identify
this is a combination of two sockets, usually a client socket and a server socket
together it can be used to identify a single and unique conversation between client and server applications.
example
192.168.1.2:5274, 192.168.1.20:80
this is used to view all current connections and listening ports. it may also be usefull in revealing suspicious connections.
what is the
netstat
command used for
if a server is offering web services and file sharing services then it needs to know which service a host requires if an incoming message is destined for port 80 then the server knows that this message is bound for a web server application and is placed in the appropriate cue to be processed
give an example of a server hosting web and file sharing services and how it distinguishes between these
these can be either source or destination ports and can be used by organisations to register an application such as IM or gaming
the range is from 1024 through 49151
describe
registered ports
and their range
what are the port(s) and transport protocol(s) of
Domain Name Service (DNS)
this uses:
- port 53
- UDP - for client IP queries. (queries and replies are sent in one packet so if it is lost it can simply be asked for and retransmitted)
- TCP - for zone transfers - this is a DNS server sharing records with another DNS server
what are the port(s) and transport protocol(s) of
Hypertext Transfer Protocol (HTTP)
this uses:
- port 80 TCP
describe in 2 steps the process of
receiving a message via
Transmission Control Protocol (TCP)
- the receiver receives a block of segments and puts them in the correct order
- if all segments for that block are received and correct then it sends an acknowledment message back to the sender and waits for the next block of segments
where are
port numbers
assigned and what is there use
these are assigned at layer 4 (transport layer) and are a way of identifying unique conversations or services
what are the port(s) and transport protocol(s) of
Trivial File Transfer Protocol (TFTP)
this uses:
- port 69 UDP
this uses:
- port 110 TCP
what are the port(s) and transport protocol(s) of
Post Office Protocol version 3 (POP3)
these are assigned at layer 4 (transport layer) and are a way of identifying unique conversations or services
where are
port numbers
assigned and what is there use
this uses:
- port 25 TCP
what are the port(s) and transport protocol(s) of
Simple Mail Transfer Protocol (SMTP)
what are the port(s) and transport protocol(s) of
Simple Mail Transfer Protocol (SMTP)
this uses:
- port 25 TCP
these will decide:
- how client and server will communicate
- what information client and server will communicate
- the transport layer protocol that will be used
what do
application layer services
such as HTTP, DNS, FTP, DHCP. decide
this is known as a ‘best effort protocol’ and resides on the layer 4 (transport layer). this protocol is in contrast to TCP in that it does not ensure all messages are delivered by using acknowledgments.
instead a message is broken up and sent without care of if they are received or not
describe
User Datagram Protocol (UDP)
this uses:
- port 23 TCP
what are the port(s) and transport protocol(s) of
Telnet
describe
private ports
and their range
often used as source ports these can be used by any application
there range run from 49152 through 65535
describe the
Uniform Resource Locator (URL)
this includes the protocol and the namespace of the document, does not include the fragment
this is a combination of two sockets, usually a client socket and a server socket
together it can be used to identify a single and unique conversation between client and server applications.
example
192.168.1.2:5274, 192.168.1.20:80
what is a
socket pair
and what can it identify
what are the port(s) and transport protocol(s) of
Post Office Protocol version 3 (POP3)
this uses:
- port 110 TCP
this uses:
- port 443 TCP
what are the port(s) and transport protocol(s) of
Hypertext Transfer Protocol Secure (HTTPS)
this is a layer 4 (transport layer) protocol that is responsible for ensuring a message is delivered in full and reassembled correctly when received
describe what
Transmission Control Protocol (TCP)
is
describe the
well known ports
and there range
these are destination ports that are associated with common network applications such as HTTP or SSH
there range is from 1 to 1023
this includes the protocol and the namespace of the document, does not include the fragment
describe the
Uniform Resource Locator (URL)
what are the port(s) and transport protocol(s) of
Dynamic Host Configuration Protocol (DHCP)
this uses:
- port 67 UDP - on the server
- port 68 UDP - on the client