chp 9 nat

Question 1

ipv4 private address space

Answer 1

• not enough ip addresses
• private addresses are used within organizations
• not routed on internet
• must be translated by nat

Question 2

network address translation (nat)

Answer 2

• to conserve public ipv4 addresses
• implemented at border network devices
• private addresses are translated to public addresses
• internal address is hidden

Question 3

static nat

Answer 3

• one to one mapping of local and global addresses
• configured by network admin and remain constant
• useful when internal servers must be accessible from the outside network

Question 4

dynamic nat

Answer 4

• uses pool of public addresses
• assigns them on first come first serve basis
• requires enough public addresses to satisfy all simultaneous users

Question 5

port address translation (pat)

Answer 5

• maps multiple private ip addresses to public ip addresses
• uses the pair source port and source ip address to keep track of what traffic belongs to each client
• aka nat overload
• validates that incoming packets were requested, added security

Question 6

benefits of nat

Answer 6

• conserves ip addresses
• increases the flexibility of connections to the public network
• provides consistency for internal network addressing schemes
• provides network security

Question 7

disadvantages of nat

Answer 7

• worse performance
• end to end addressing is lost
• end to end traceability is lost
• initiating tcp connections can be interrupted

Question 8

port forwarding

Answer 8

• forwarding a network port from one network node to another
• a packet sent to a public ip and port of a router can be forwarded to a private ip and port inside the network
• useful when server with private ip needs to be reached from outside network