1. UNIX OS
Lecture IV
Simonas Kareiva
Vilnius University
Faculty of Mathematics
and Informatics
Preparation of the material was supported by the project „Increasing Internationality in Study
Programs of the Department of Computer Science II“, project number VP1–2.2–ŠMM-07-K-
02-070, funded by The European Social Fund Agency and the Government of Lithuania.

2. Lecture #4 outline (part I)
Introduction to TCP/IP and OSI. IP addressing
IP and MAC address relation
UNIX OS networking
ping and traceroute
arp, ifconfig and route
2

3. TCP/IP
Set of data transfer protocols (HTTP / FTP / DNS / …)
Created 1973-1974, installed 1983
Abstraction levels (see further)
Encapsulation
OSI model
3

4. 4

5. 5

6. In theory
Computer 2RouterRouterComputer 1
6

7. Real life (simplified)
Computer 2
Router
Router
Computer 1 Router
Router
Router
7

8. How does communication work?
Ethernet
Satellite
connecti
on/
optics/
etc.
WiFi
Application
Transport
Network
Connection
Application
Transport
Network
Connection
Network
Connection
Network
Connection
8

9. IP address and mask
192.168.1.112/22
11000000.10101000.00000001.11100000
255.255.252.0
192.168.1.0 - ?
192.168.3.225 - ?
9

10. Task
IP address is 10.250.1.48/19
Questions:
 What is the expression of this network mask in full format?
 What is the maximum number of computers that can be
connected to this network?
 What’s the class of this IP address?
10

11. Answer comes from ipcalc
> ipcalc 10.250.1.48/19
addresss: 10.250.1.48 00001010.11111010.000 00001.00110000
Netmask: 255.255.224.0 = 19 11111111.11111111.111 00000.00000000
Wildcard: 0.0.31.255 00000000.00000000.000 11111.11111111
=>
Network: 10.250.0.0/19 00001010.11111010.000 00000.00000000
HostMin: 10.250.0.1 00001010.11111010.000 00000.00000001
HostMax: 10.250.31.254 00001010.11111010.000 11111.11111110
Broadcast: 10.250.31.255 00001010.11111010.000 11111.11111111
Hosts/Net: 8190 Class A, Private Internet
11

12. Another IP writing method
#!/bin/sh
IPTONUM ()
{
IP=$1; IPNUM=0
for (( i=0 ; i<4 ; ++i )); do
((IPNUM+=${IP%%.*}*$((256**$((3-${i}))))))
IP=${IP#*.}
done
echo $IPNUM
}
NUMTOIP ()
{
echo -n $(($(($(($((${1}/256))/256))/256))%256)).
echo -n $(($(($((${1}/256))/256))%256)).
echo -n $(($((${1}/256))%256)).
echo $((${1}%256))
}
12

13. IP classes (historical)
Class First octet in
binary system
First octet
from-to
Network
identifier
Ammount of
networks
A 0XXXXXXX 0 - 127 a. 27
= 128
B 10XXXXXX 128 - 191 a.b. 214
= 16,384
C 110XXXXX 192 - 223 a.b.c. 221
=
2,097,152
13

14. MAC address
08:00:20:d1:b0:0a
 080020 – Sun Microsystems Inc.
 d1b00a – unique product ID
MAC / IP connection
DHCP
 static DHCP
 dynamic DHCP
14

15. Working in network with UNIX OS
talk jonas@developers.firma.lt
lynx www.delfi.lt
echo pse call| mail –s important evelina@pardavimai
ping 192.168.0.1
ifconfig
15

16. ifconfig
> ifconfig
eth0 Link encap:Ethernet HWaddr 00:22:15:88:9c:93
inet addr:82.135.156.42 Bcast:82.135.156.255 Mask:255.255.255.0
inet6 addr: fe80::222:15ff:fe88:9c93/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:2038944517 errors:0 dropped:0 overruns:0 frame:0
TX packets:2634746425 errors:0 dropped:0 overruns:0 carrier:1
collisions:0 txqueuelen:1000
RX bytes:592322463 (592.3 MB) TX bytes:3453432517 (3.4 GB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:5318385 errors:0 dropped:0 overruns:0 frame:0
TX packets:5318385 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:2254159344 (2.2 GB) TX bytes:2254159344 (2.2 GB)
16

17. ping
> ping 24.93.4.206
PING 24.93.4.206 (24.93.4.206): 56 data bytes
64 bytes from 24.93.4.206: icmp_seq=0 ttl=240 time=157.010 ms
64 bytes from 24.93.4.206: icmp_seq=1 ttl=240 time=151.762 ms
64 bytes from 24.93.4.206: icmp_seq=2 ttl=240 time=314.532 ms
ping: sendto: Network is down
ping: sendto: Network is down
ping: sendto: Network is down
^C
--- 24.93.4.206 ping statistics ---
6 packets transmitted, 3 packets received, 50% packet loss
round-trip min/avg/max/stddev = 151.762/207.768/314.532/75.524 ms
17

18. traceroute
> traceroute cisco.netacad.net
traceroute to cisco.netacad.net (128.107.229.50), 30 hops max, 40 byte packets
1 gw.ep.lt (82.135.156.254) 0.966 ms 0.940 ms 0.926 ms
2 212-59-21-193.static.telecom.lt (212.59.21.193) 2.727 ms 2.716 ms 2.703 ms
3 213-190-60-93.telecom.lt (213.190.60.93) 2.892 ms 2.880 ms 2.868 ms
4 war-b3-link.telia.net (213.248.85.89) 11.790 ms 11.779 ms 11.766 ms
5 hbg-bb2-link.telia.net (80.91.251.217) 37.136 ms 37.124 ms 37.112 ms
6 ldn-bb2-link.telia.net (80.91.249.14) 41.709 ms ldn-bb2-link.telia.net (80.91.250.151)
41.859 ms ldn-bb2-link.telia.net (80.91.254.7) 41.842 ms
7 ash-bb1-link.telia.net (80.91.251.209) 123.663 ms 123.964 ms ash-bb1-link.telia.net
(213.248.65.210) 125.426 ms
8 192.205.34.209 (192.205.34.209) 122.910 ms 123.278 ms *
9 cr1.wswdc.ip.att.net (12.122.135.14) 196.349 ms 195.994 ms 195.979 ms
10 cr2.phlpa.ip.att.net (12.122.4.53) 197.221 ms 199.154 ms 199.135 ms
11 cr2.cl2oh.ip.att.net (12.122.2.209) 215.193 ms 213.361 ms 213.550 ms
12 cr1.cl2oh.ip.att.net (12.122.2.125) 213.099 ms 221.672 ms 221.645 ms
13 cr1.cgcil.ip.att.net (12.122.2.205) 222.744 ms 222.733 ms 222.720 ms
14 cr1.sffca.ip.att.net (12.122.4.121) 221.392 ms 221.377 ms 221.366 ms
15 gar1.sj2ca.ip.att.net (12.123.15.1) 205.537 ms 203.746 ms 203.730 ms
16 12.118.124.10 (12.118.124.10) 228.697 ms 228.684 ms 228.673 ms
17 sjck-dmzbb-gw1.cisco.com (128.107.239.9) 190.264 ms 190.251 ms 190.652 ms
18 sjc12-dmzbb-gw1-g1-37.cisco.com (128.107.224.165) 302.883 ms 302.868 ms 302.650 ms
19 sjc12-dmzdc-gw1-gig5-2.cisco.com (128.107.224.22) 303.049 ms 303.037 ms 303.025 ms
20 * * *
21 * * *
22 * * *
18

19. arp
> arp -an
? (82.135.156.222) at 00:c0:02:2a:4e:6d [ether] on eth0
? (82.135.156.16) at 00:15:60:57:06:cd [ether] on eth0
? (82.135.156.83) at 00:0e:0c:4e:62:f8 [ether] on eth0
? (82.135.156.84) at 00:06:29:39:63:c3 [ether] on eth0
? (82.135.156.6) at 00:80:a3:8c:0d:72 [ether] on eth0
? (82.135.156.88) at 00:11:d8:94:a9:4a [ether] on eth0
? (82.135.156.21) at 00:18:f3:87:31:17 [ether] on eth0
? (82.135.156.15) at 00:0e:a6:34:37:a1 [ether] on eth0
? (82.135.156.23) at 00:0c:f1:ed:c8:56 [ether] on eth0
? (82.135.156.55) at 00:10:5a:5a:06:f1 [ether] on eth0
? (82.135.156.254) at 00:30:48:88:d9:1e [ether] on eth0
? (82.135.156.201) at 00:08:02:ef:fa:a4 [ether] on eth0
19

20. route
> route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
193.219.94.168 82.135.156.254 255.255.255.255 UGH 0 0 0 eth0
193.219.94.141 82.135.156.254 255.255.255.255 UGH 0 0 0 eth0
82.135.156.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
0.0.0.0 82.135.156.254 0.0.0.0 UG 100 0 0 eth0
20

21. Routing
Computer 2
172.16.0.2/28
Router 3
Router 1
Computer 1
192.168.1.1/24
Router 2
Computer 3
192.168.3.1/24
internet
21

22. 22

23. 23

24. 24

25. Lecture #4 outline (part II)
Overview of UNIX command line tools:
 cut
 diff
 awk
 sed
 expand
 grep
 strings
 tr
 uniq
 zcat
25

26. cut
> echo aa:bb cc dd:ee | cut -d : -f 2
bb cc dd
> echo aa:bb cc dd:ee | cut -d " " -f 2
cc
> echo aa:bb cc dd:ee | cut -d " " -f 1,2
aa:bb cc
> echo aa:bb cc dd:ee | cut -d " " -f 1,2,3
aa:bb cc dd:ee
> cut -d : -f 1,5 /etc/passwd | tail -3
_installer:Installer
_atsserver:ATS Server
_unknown:Unknown User
26

27. diff
> echo "Firstnsecond" > 1.txt
> echo "Firstnthird" > 2.txt
> diff 1.txt 2.txt
2c2
< second
---
> third
> diff 1.txt 2.txt > diff.txt
> patch -p0 1.txt < diff.txt
patching file 1.txt
> cat 1.txt
First
third
27

28. expand
> printf "atbn"
a b
> printf "atbn" | hexdump
0000000 0961 0a62
0000004
> printf "atbn" | expand | hexdump
0000000 2061 2020 2020 2020 0a62
000000a
28

29. grep
> grep ^a /etc/passwd
alias:*:81:81:User &:/var/qmail/alias:/nonexistent
> grep ^c /etc/passwd
cyrus:*:60:60:the cyrus mail server:/nonexistent:/sbin/nologin
courier:*:465:465:Courier Mail
System:/var/spool/courier:/sbin/nologin
> grep -c nologin$ /etc/passwd
29
> tail -f httpd-error.log | grep denied
[Sun Oct 4 19:18:12 2012] [error] [client 78.60.155.45]
(13)Permission denied: cannot read directory for multi:
/users/eduardas/www/
> grep -E '(error|failure)' /var/log/console | grep -vc connect_to
1945
29

30. strings
> strings /var/log/wtmp | grep -A4 simonask
simonask
88.223.26.58
Jttypa
Jttypc
Jttypa
> strings /bin/sync | grep error
$FreeBSD: src/lib/libc/i386/sys/cerror.S,v 1.10 1999/08/27 23:59:38
peter Exp $
error:
Authentication error
Exec format error
Input/output error
Undefined error: 0
30

31. tr
> cat bug.lt | tr e 3
W3 ar3 us3r group of BSD syst3ms.
Th3 group was 3stablish3d in th3 summ3r of 2002.
It happ3n3d in small city of North Lithuania.
> cat bug.lt | tr '[a-z]' '[A-Z]'
WE ARE USER GROUP OF BSD SYSTEMS.
THE GROUP WAS ESTABLISHED IN THE SUMMER OF 2002.
IT HAPPENED IN SMALL CITY OF NORTH LITHUANIA.
31

32. uniq
> grep DNS ppp.log | awk '{ print $10 }' | sort | uniq
194.176.32.142
194.176.32.163
> grep Illegal cache.log | tail -1
2009/10/04 19:37:34| urlParse: Illegal character in hostname
'www,youtube.lt’
> grep Illegal cache.log | cut -d " " -f 8 | sort | uniq -c | sort
-rn | head
760 '[2a01:138:a001:201:'
57 '2a01%3a138%3aa001%3a201%3a%3a24'
57 '2a01%3a138%3aa001%3a201%3a%3a23'
57 '2a01%3a138%3aa001%3a201%3a%3a22'
57 '2a01%3a138%3aa001%3a201%3a%3a21'
12 '%20ssl.google-analytics.com'
7 'www,youtube,com'
4 'evi ka-pc'�
3 'www,youtube.lt'
3 'vista.%20liedm.lt’
32

33. zcat
> cat > test2.sh
#!/bin/sh
echo date
exit 0;
> gzip test2.sh
> cat test2.sh.Z
;??Jtest2.shSV?O???/??JM??WHI,I?J??,Q0???d?I>
> zcat test2.sh.Z
#!/bin/sh
echo date
exit 0;
33

34. sed
> echo day | sed s/day/night/
night
> echo "123 abc" | sed 's/[0-9]*/& &/'
123 123 abc
> echo left right | sed 's/([a-z]*) ([a-z]*)/2 1/'
right left
> sed '/start/,/stop/ s/#.*//'
?
34

35. sed
Compare:
 sed 's/([a-zA-Z]*) ([a-zA-Z]*) /1 /'
 sed 's/[a-zA-Z]* //2'
 sed 's/./&:/20'
 sed 's/^..................../&:/'
 sed -n 's/jonas/&/p' <file
 grep jonas file
 sed 'y/abcdef/ABCDEF/’
 tr abcdef ABCDEF
35

36. Exercise (sed)
#!/bin/sh
sed -n '
/begin/,/end/ {
s/#.*//
s/[ ^I]*$//
/^$/ d
p
}
’
36

37. sed
#!/bin/sh
# A way to clear the lines that start with #
# (comments) between words ‘begin’ and ‘end’
sed -n '
/begin/,/end/ {
s/#.*//
s/[ ^I]*$//
/^$/ d
p
}
'
37

38. sed (advanced)
> cat cat.txt
This is my cat
my cat's name is betty
This is my dog
my dog's name is frank
> sed 'N;s/n / /;P;D;' cat.txt
This is my cat my cat's name is betty
This is my dog my dog's name is frank
N – adds a second line to the buffer
s – substitution command
/n / - equivalence of a new line and space
/ / - substitution to one space
P – prints first line of buffer
D - deletes the buffer and continues to the next line
38

39. awk
> ls -l
-rwxrwxrwx@ 1 simonask staff 7497216 Rgs 14 15:59 UNIX_1.pps
> ls -l | awk ' BEGIN { print ”BylattSavininkas" } { print $9,
"tt", $3} END { print " - DONE -" } '
file Owner
UNIX_1.pps simonask
- DONE -
> date
Sunday, 2012 m. spalio 4 d. 20:21:58 EEST
> date | awk '{print $1}'
Sunday,
> date | awk '{print $2}'
2012
39

40. awk
BEGIN {
print ”enter number";
}
{
print ”Number’ ", $1, ” square is ", $1*$1;
print ”enter one more number";
}
END {
print ”Bye"
}
40

41. awk
awk '{print $2, $1}' read.txt
awk '{print NR "t" $0}’ read.txt
awk '{l=length();s=int((79-l)/2); printf "%"(s+l)"sn",$0}'
Compare this:
 head -10
 awk 'NR < 11’
 awk '!/search/' read.txt
 grep –v search read.txt
41

42. Excercises
ls -d *.sh | sed 's/(.*).sh$/cp "&" 1/' | sh
____________________________________________________________
STR="`sed <<<"$STR" "s/(.)/1('s*
+s*')?/g;s/('s*
+s*')?$//"`"
____________________________________________________________
find ${1-.} -type d -print | env LC_ALL='C' sort -if |
sed -e "s,^${1-.},,"
-e "/^$/d"
-e "s,[^/]*/([^/]*)$,`-----1,"
-e "s,[^/]*/,| ,g"
42

43. #!/usr/bin/perl -w # camel code
use strict;
$_='ev
al("seek040D
ATA,0, 0;");foreach(1..3)
{<DATA>;}my @camel1hump;my$camel;
my$Camel ;while( <DATA>){$_=sprintf("%-6
9s",$_);my@dromedary 1=split(//);if(defined($
_=<DATA>)){@camel1hum p=split(//);}while(@dromeda
ry1){my$camel1hump=0 ;my$CAMEL=3;if(defined($_=shif
t(@dromedary1 ))&&/S/){$camel1hump+=1<<$CAMEL;}
$CAMEL--;if(d efined($_=shift(@dromedary1))&&/S/){
$camel1hump+=1 <<$CAMEL;}$CAMEL--;if(defined($_=shift(
@camel1hump))&&/S/){$camel1hump+=1<<$CAMEL;}$CAMEL--;if(
defined($_=shift(@camel1hump))&&/S/){$camel1hump+=1<<$CAME
L;;}$camel.=(split(//,"040..m`{/J047134}L^7FX"))[$camel1h
ump];}$camel.="n";}@camel1hump=split(/n/,$camel);foreach(@
camel1hump){chomp;$Camel=$_;y/LJF7173175`047/061062063
064065066067070/;y/12345678/JL7F175173047`/;$_=reverse;
print"$_040$Cameln";}foreach(@camel1hump){chomp;$Camel=$_;y
/LJF7173175`047/12345678/;y/12345678/JL7F1751730 47`/;
$_=reverse;print"040$_$Cameln";}';;s/s*//g;;eval; eval
("seek040DATA,0,0;");undef$/;$_=<DATA>;s/s*//g;( );;s
;^.*_;;;map{eval"print"$_"";}/.{4}/g; __DATA__ 124
1 501450401651631450401571 460401 410
40143141 1551451 540401 51155 141
1471450 40151156 040141 16316 3
157143 15114116 41511 57156
040167 1511641 50040 1201
45162 15404015 1163 04014
10401 641621 41144 145
15514 1162 15304 0157
146 04011 7047 1221
4515 11541 54171 040
046 01210116 316
315 714315 114
116 4145163 054
040 11115614 3056
040 12516314514 4040
1671 511641 500 40160
145162 155151
163163 1511
57156056
43