FreeBSD Operating System

Упражнение 1:

Номер 1

What is true about recv packet type, used by ipfw program?

Ответ:

(1) The recv interface can be tested on incoming packets

(2) You can specify via together with recv

(3) The recv interface can be tested on outgoing packets

(4) The recv interface describes all packets arriving by the specified interface

Номер 2

What is true about xmit packet type, used by ipfw program?

Ответ:

(1) The xmit interface can be tested only on outgoing packets

(2) You must specify the keyword in when you use xmit

(3) You can specify via together with xmit

(4) The xmit interface describes all packets going out by the specified interface

Номер 3

What is true about via packet type, used by ipfw program?

Ответ:

(1) The via interface all packets going by the specified interface

(2) "interface" may be an interface name or an IP address associated with only one interface

(3) You can specify via together with xmit

(4) You can specify via together with recv

Упражнение 2:

Номер 1

Which keyword in ipfw rules discards the packet and stops processing the rules?

Ответ:

(1) allow

(2) deny

(3) unreach

(4) reset

Номер 2

Which keyword in ipfw rules discards the packet and sends an ICMP host unreachable message to the sender, then stops processing the rules?

Ответ:

(1) allow

(2) deny

(3) unreach

(4) reset

Номер 3

Which keyword in ipfw rules discards the packet and sends a TCP reset message and stops processing the rules?

Ответ:

(1) allow

(2) deny

(3) unreach

(4) reset

Упражнение 3:

Номер 1

Which keyword in ipfw rules continues processing the rules at pointed rule number?

Ответ:

(1) count

(2) divert

(3) tee

(4) skipto

Номер 2

Which keyword in ipfw rules sends a copy of the packet to the divert socket bound to the pointed port and continues processing the rules?

Ответ:

(1) count

(2) divert

(3) tee

(4) skipto

Номер 3

Which keyword in ipfw rules diverts the packet to the divert socket bound to pointed port and stops processing the rules?

Ответ:

(1) count

(2) divert

(3) tee

(4) skipto

Упражнение 4:

Номер 1

What kind of profile allows only local traffic via the loopback interface?

Ответ:

(1) The simple profile

(2) The client profile

(3) The closed profile

(4) The open profile

Номер 2

What kind of profile is intended for a system that does provide a number of publicly accessible services to the Net?

Ответ:

(1) The simple profile

(2) The client profile

(3) The closed profile

(4) The open profile

Номер 3

What kind of profile is intended for a system that does not provide many publicly accessible services to the Net?

Ответ:

(1) The simple profile

(2) The client profile

(3) The closed profile

(4) The open profile

Упражнение 5:

Номер 1

What is false about network address translation?

Ответ:

(1) Organization uses just one outer IP address

(2) You can connect two machines on different NAT networks

(3) Special software makes all traffic from the network to the outside world look as if it’s coming from one system

(4) NAT can be significantly cheaper because you don't pay money for additional addresses

Номер 2

What program can be used only for IP aliasing?

Ответ:

(1) natd

(2) pppd

(3) squid

(4) ipfw

Номер 3

What is false about proxy servers?

Ответ:

(1) A proxy server converts requests for specific protocols

(2) A proxy server can cache data locally

(3) Client does not need to know anything about the proxy server

(4) ftp understands proxies, and uses them for non-interactive connections only

Упражнение 6:

Номер 1

What is false about program ping?

Ответ:

(1) It sends an ICMP echo packet to a specific IP address and checks the reply

(2) It sends packets of 64 bytes

(3) By default, ping continues until you stop it

(4) It is used to test network layer of the system

Номер 2

What information ping can't give you?

Ответ:

(1) How many interfaces were passed by each packet to get to its destination

(2) How long it takes for each packet to get to its destination and back

(3) How many packets didn’t get to their destination or back

(4) A summary of packet statistics

Номер 3

What kind of ping FreeBSD systems do not respond, but most other systems do?

Ответ:

(1) unicast

(2) broadcast

(3) multicast

(4) loopback

Упражнение 7:

Номер 1

What is false about program traceroute?

Ответ:

(1) It sends TCP packets to the destination

(2) It modifies the time-to-live field in the IP header

(3) The time-to-live field specifies the number of hops that a packet can go before it is discarded

(4) The system that discards a packet should send back an ICMP destination unreachable message

Номер 2

What is false about program traceroute?

Ответ:

(1) By default, traceroute tries each hop three times

(2) traceroute tries prints out the times as each hop happens

(3) If there is no reply after a timeout period traceroute prints that the route is unreachable

(4) By default, a timeout period for reply from hop is 5 seconds

Номер 3

What is false about program tcpdump?

Ответ:

(1) tcpdump is a program that monitors a network interface

(2) It uses the Berkeley Packet Filter (bpf), an optional component of the kernel

(3) You mustn't be root to run it

(4) If it is run without any parameters, tcpdump displays all traffic on the first active network interface

Упражнение 8:

Номер 1

What service web browsers use to access the Web?

Ответ:

(1) NFS

(2) POP

(3) SMTP

(4) HTTP

Номер 2

Wha is the primary service for sending mail round the Internet?

Ответ:

(1) NFS

(2) ssh

(3) SMTP

(4) HTTP

Номер 3

What service is used to communicate with a remote shell?

Ответ:

(1) ssh

(2) POP

(3) SMTP

(4) HTTP

Упражнение 9:

Номер 1

What is false about public key cryptography technique,used in ssh?

Ответ:

(1) Passwords are sent across the Net in the encrypted form

(2) You have two keys, one of which you can give away freely, and the other of which you guard carefully

(3) Data encrypted with the public key can be decrypted with the private key

(4) Data encrypted with the private key can be decrypted with the public key

Номер 2

What is false about the challenge-response method, used in ssh?

Ответ:

(1) To initiate an ssh connection, ssh sends your private key to the sshd process on the remote system

(2) Method is used for authentication

(3) The remote system uses a copy of this key to encrypt a random text, a challenge, which it sends back to your system

(4) Only your system can decode the challenge

Номер 3

What is false about creating and distributing keys in ssh?

Ответ:

(1) Keys are created with the program ssh-keygen

(2) Before you can use these keys, you need to get the public keys on the remote site

(3) The public keys are in ASCII

(4) You can send the private keys by mail

Упражнение 10:

Номер 1

What is false about tunneling?

Ответ:

(1) Tunneling is a technique for encapsulating an IP connection inside another IP connection

(2) Tunneling adds encryption to an otherwise unencrypted connection

(3) Tunneling provides access to a service on a system that does not generally supply this service to the Internet

(4) If the server is firewalled from the global Internet, you can access it directly

Номер 2

What is false about ssh tunnels?

Ответ:

(1) The ssh tunnel creates a local connection at each end and a separate secure connection across the Internet

(2) You can set up a reverse tunnel

(3) You can't specify a command to execute

(4) If you’re running protocol version 1, you can use sleep with an appropriately long timeout

Номер 3

What option tells ssh to go into the background after authentication?

Ответ:

(1) -f

(2) -N

(3) -L

(4) -R

Упражнение 11:

Номер 1

Which of the programs is not used for remote copying files between systems?

Ответ:

(1) scp

(2) ssh

(3) rcp

(4) ftp

Номер 2

What is false about scp?

Ответ:

(1) scp is a variant of ssh used for remote copying

(2) You don’t have to supply full path names to scp

(3) Relative paths are always relative to the current local directory on the remote machine

(4) If you need to authenticate as a different user, you can use the form user@system

Номер 3

What is false about ftp?

Ответ:

(1) ftp transfers only large files long distances across the Net

(2) You need to have permission to access the remote system using ftp

(3) ftp servers accept the name "anonymous"

(4) The server may have multiple names, and the one you use may not be its canonical name

Упражнение 12:

Номер 1

What is false about the Network File System?

Ответ:

(1) It is the standard way to share UNIX files across a network

(2) You access NFS file systems via the disk driver, which is part of the kernel

(3) NFS with other UNIX file systems are accessible in a single tree by mounting them on a specific directory

(4) You don’t need any particular software to run as an NFS client

Номер 2

What is false about the Network File System?

Ответ:

(1) NFS handles disk files and directories

(2) NFS exports device nodes in UFS file systems

(3) NFS interprets the fact that devices are on another system

(4) NFS mimics a local file system across the network

Номер 3

What is false about the Network File System?

Ответ:

(1) You can't mount a remote file system on a directory that is not empty

(2) NFS exports file systems, not directory hierarchies

(3) If the NFS server system runs devfs, the device nodes are not exported

(4) If you refer to the devices and no driver for the specified major number exists on your local system, the request will fail

FreeBSD Operating System - тест 24