Questions and answers

1. Networking Configuration

1.1.

Is configuring the loopback interface necessary for a system without networking?

Yes, as the loopback interface is used by various local services during normal operation.

Use of loopback interface

1.2.

What is the purpose of configuring a default gateway?

In order to route networking traffic to destinations other than the local network, the default gateway is used.

Defining a default gateway

1.3.

Which command is used to scan for available wireless networks?

iwlist is the command by which to scan for available wireless networks.

Scan for wireless networks

1.4.

What do VPN implementations - like IPSEC, VPND, SSH and (many) Cisco Routers - have in common?

They all create a secure tunnel through a possibly insecure network (like the internet).

Common in VPN's

1.5.

Name the three protocols which are used in an IPSEC implementation.

ESP (Encapsulating Security Payload), AH (Authentication Header) and IKE (Internet Key Exchange).

Protocols used by IPSEC

1.6.

Which tool is the first to use in order to detect mulitple use of your IP address in the same network?

Using arp one can determine which MAC-addresses are using your IP-address.

Detecting IP addresses

1.7.

What ICMP message will be sent back to a traceroute client by every system along the path to the destination specified?

An ICMP TIME_EXCEEDED reply is sent back to the packet's source address. This is because traceroute sents out a stream of packets to the destination, starting with the TTL-field set to 1 and incrementing it by one every time until the destination replies.

Traceroute and ICMP

Copyright Snow B.V. The Netherlands