Lynx Consultants presentation to train Junior Engineers into the basics of networking

1. Marc
Cluet
–
Lynx
Consultants

2. What we’ll cover?
¡ Understand
how
networking
works
¡ Understand
all
the
basic
networking
protocols
¡ Understand
how
DNS
works
¡ Be
more
awesome!
Lynx
Consultants
©
2013

3. What is a Network?
¡ A
computer
network,
or
simply
a
network,
is
a
collection
of
computers
and
other
hardware
interconnected
by
communication
channels
that
allow
sharing
of
resources
and
information.[1]
Where
at
least
one
process
in
one
device
is
able
to
send/receive
data
to/from
at
least
one
process
residing
in
a
remote
device,
then
the
two
devices
are
said
to
be
in
a
network.
A
network
is
a
group
of
devices
connected
to
each
other.
Networks
may
be
classified
into
a
wide
variety
of
characteristics,
such
as
the
medium
used
to
transport
the
data,
communications
protocol
used,
scale,
topology,
benefit,
and
organizational
scope.
(gotta
love
Wikipedia)
Lynx
Consultants
©
2013

4. So in plain words…
¡ A
network
connects
2
or
more
computers
together
§ LAN
(Local
Area
Network)
is
inside
a
known
location
(office,
home,
etc)
§ WAN
(Wide
Area
Network)
is
a
network
that
connects
two
or
more
LANs
Lynx
Consultants
©
2013

5. The Internet
¡ Internet
is
a
network
that
connects
in
a
fault
tolerant
way
many
networks
¡ Our
current
version
of
the
Internet
works
over
the
protocol
IPv4
with
the
new
protocol
IPv6
starting
to
have
some
presence
Lynx
Consultants
©
2013

6. Internet IPv4
¡ The
most
common
protocol
in
Internet
is
right
now
IPv4
¡ IPv4
has
been
the
Internet
protocol
since
1980
(RFC
760)
¡ IPv4
uses
32
bit
addresses,
having
a
total
space
of
4,294,967,296
unique
IPs
Lynx
Consultants
©
2013

7. IPv4 IP address
¡ An
IPv4
IP
address
is
divided
in
8
bit
chunks
(1
byte
per
number)
Lynx
Consultants
©
2013

8. IPv4 IP netmask
¡ A
netmask
defines
what
your
local
network
is,
anything
inside
that
netmask
is
considered
local
to
you
Lynx
Consultants
©
2013

9. IPv4 Problems
¡ IPv4
is
running
out
of
IP
addresses
(last
/8
delivered
this
year)
¡ IPv4
is
not
secure
for
most
uses
¡ IPv4
was
designed
in
the
70ies
so
its
up
for
a
review
Lynx
Consultants
©
2013

10. IPv6 saves the day!
¡ IPv6
is
the
new
internet
protocol
¡ Uses
128
bit
addresses
¡ There’s
more
IP
addresses
in
IPv6
than
atoms
on
planet
Earth
Lynx
Consultants
©
2013

11. IP gateways
¡ As
IP
is
the
Internet
Protocol
it
has
to
know
how
to
talk
to
other
networks
¡ A
gateway
server
is
the
one
who
sits
in
two
networks
at
the
same
time,
relying
packets
between
those
networks
Lynx
Consultants
©
2013

12. So then how the Internet works?
¡ Gateways
keep
relying
your
message
from
network
to
network
until
it
reaches
the
destination
¡ The
path
to
reach
its
destination
can
change
all
the
time
Lynx
Consultants
©
2013

13. IP protocols
¡ IP
can
run
lots
of
different
protocols
inside,
the
most
known
ones
are
§ TCP
(Transmission
Control
Protocol)
§ UDP
(User
Datagram
Protocol)
§ ICMP
(Internet
Control
Message
Protocol)
Lynx
Consultants
©
2013

14. IP protocol definitions
¡ TCP
sends
packets
with
complete
assurance
that
they’ll
reach
their
destination
¡ UDP
sends
packets
without
any
kind
of
assurance
that
they’ll
reach
their
destination
¡ ICMP
sends
control
messages
auxiliary
to
the
IP
protocol
(like
ping,
traceroute,
etc)
Lynx
Consultants
©
2013

15. TCP Protocol
¡ Keeps
track
of
all
the
packets
it
sends
(serial
num)
¡ Destination
acknowledges
(ACK)
every
packet
received
¡ Packets
can
arrive
in
any
order
and
they’ll
be
reordered
at
destination
Lynx
Consultants
©
2013

16. TCP Ports
¡ TCP
can
listen
or
talk
in
several
“channels”
at
the
same
time
¡ Ports
are
the
channels
where
TCP
(and
UDP)
talk,
there’s
a
total
of
65,536
channels
¡ Most
common
Ports
§ 80
http
§ 443
https
§ 25
smtp
§ 110
pop3
§ 143
imap
Lynx
Consultants
©
2013

17. UDP Protocol
¡ UDP
sends
packets
as
TCP
to
ports,
but
there’s
no
guarantee
that
the
packets
will
reach
its
destination.
¡ This
is
ideal
for
any
kind
of
protocol
that
doesn’t
need
all
its
packets
§ Video
Streaming
§ Radio
Streaming
Lynx
Consultants
©
2013

18. ICMP Protocol
¡ ICMP
sends
auxiliary
messages
that
help
Internet
routing
¡ Used
in
all
of
our
common
diagnostic
tools
§ PING
(icmp
echo)
§ TRACEROUTE
(icmp
route)
Lynx
Consultants
©
2013

19. ICMP - Ping
¡ Ping
sends
a
packet
to
a
destination
and
reads
the
reply
¡ Bases
itself
on
ICMP
echo
¡ Can
be
filtered
by
routers
and
inbetween
policy
filters
Lynx
Consultants
©
2013

20. ICMP - Traceroute
¡ Traceroute
sends
requests
to
every
single
hop
between
us
and
a
destination
¡ This
is
based
on
one
special
type
of
ICMP
packet
¡ Some
routers
can
decide
to
filter
traceroute,
in
that
case
*
will
appear
instead
of
the
TTL
Lynx
Consultants
©
2013

21. What is DNS?
¡ The
Internet
works
with
IP
addresses
¡ How
can
we
remember
always
that
google
is
173.194.67.103?
¡ It’s
humanly
impossible!
Lynx
Consultants
©
2013

22. DNS saves the day
¡ DNS
is
a
service
(listens
on
UDP
port
53)
¡ DNS
will
give
you
the
IP
address
of
any
name
you
want
¡ It
can
give
you
more
than
one
address
for
extra
redundancy
Lynx
Consultants
©
2013

23. DNS Servers
¡ DNS
is
also
a
security
risk,
you
don’t
want
everyone
to
know
your
full
DNS
structure
¡ Big
companies
will
show
you
a
different
DNS
“view”
based
on
where
you
are
Lynx
Consultants
©
2013

24. DNS Geo Balanced
¡ DNS
is
also
very
useful
to
be
able
to
send
you
to
the
nearest
point
¡ Try
resolving
www.google.com
from
different
parts
of
the
world!
Lynx
Consultants
©
2013
www.google.com
is
173.194.41.84
www.google.com
is
74.125.26.104

25. Questions?
Lynx
Consultants
©
2013