---
author: Matija Burić
---
### Mrežni i mobilni operacijski sustavi 2025/26
# Networking: analiza, postavljanje i rješavanje problema
U ovoj vježbi prolazimo osnovne mrežne postavke, povezivost, portove, subnetiranje i sigurnosne koncepte.
### 1. Osnovne mrežne postavke
Provjeri mrežne postavke svog računala.
#### Windows
```bat
ipconfig /all
Windows IP Configuration
Ethernet adapter Ethernet:
Connection-specific DNS Suffix . :
Site-local IPv6 Address . . . . . : fec0::51f8:8cfd:eee3:2760%1
Link-local IPv6 Address . . . . . : fe80::aa9e:8ae6:47d3:a892%30
IPv4 Address. . . . . . . . . . . : 192.168.0.100
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.0.1
```
#### Linux/macOS
```shell
$ifconfig
eth0 Link encap:Ethernet HWaddr 00:15:5D:98:CD:CF
inet addr:172.28.220.88 Bcast:172.28.223.255 Mask:255.255.240.0
inet6 addr: fe80::215:5dff:fe98:cdcf/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:6 errors:0 dropped:0 overruns:0 frame:0
TX packets:18 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:837 (837.0 B) TX bytes:1318 (1.2 KiB)
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:65536 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
```
### 2. Provjera povezanosti i rute
- Pingaj svoj gateway.
#### Windows
```bat
ping 192.168.0.1
Pinging 192.168.0.1 with 32 bytes of data:
Reply from 192.168.0.1: bytes=32 time=5ms TTL=64
Reply from 192.168.0.1: bytes=32 time=6ms TTL=64
Reply from 192.168.0.1: bytes=32 time=1ms TTL=64
Reply from 192.168.0.1: bytes=32 time=1ms TTL=64
Ping statistics for 192.168.0.1:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 1ms, Maximum = 6ms, Average = 3ms
```
#### Linux/macOS
```shell
$ping 172.28.208.1
PING 172.28.208.1 (172.28.208.1): 56 data bytes
64 bytes from 172.28.208.1: seq=0 ttl=128 time=0.674 ms
64 bytes from 172.28.208.1: seq=1 ttl=128 time=1.372 ms
64 bytes from 172.28.208.1: seq=2 ttl=128 time=1.270 ms
64 bytes from 172.28.208.1: seq=3 ttl=128 time=1.256 ms
64 bytes from 172.28.208.1: seq=4 ttl=128 time=0.955 ms
64 bytes from 172.28.208.1: seq=5 ttl=128 time=1.271 ms
^C
--- 172.28.208.1 ping statistics ---
6 packets transmitted, 6 packets received, 0% packet loss
round-trip min/avg/max = 0.674/1.133/1.372 ms
```
- Pingaj javnu IP adresu
#### Windows
```bat
ping 8.8.8.8
Pinging 8.8.8.8 with 32 bytes of data:
Reply from 8.8.8.8: bytes=32 time=54ms TTL=114
Reply from 8.8.8.8: bytes=32 time=40ms TTL=114
Reply from 8.8.8.8: bytes=32 time=62ms TTL=114
Reply from 8.8.8.8: bytes=32 time=42ms TTL=114
Ping statistics for 8.8.8.8:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 40ms, Maximum = 62ms, Average = 49ms
```
- Pingaj domenu (npr. www.google.com).
#### Windows
```bat
ping www.google.com
Pinging www.google.com [142.251.39.4] with 32 bytes of data:
Reply from 142.251.39.4: bytes=32 time=44ms TTL=113
Reply from 142.251.39.4: bytes=32 time=40ms TTL=113
Reply from 142.251.39.4: bytes=32 time=38ms TTL=113
Reply from 142.251.39.4: bytes=32 time=40ms TTL=113
Ping statistics for 142.251.39.4:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 38ms, Maximum = 44ms, Average = 40ms
```
- Traceroute prema 8.8.8.8
#### Windows
```bat
tracert 8.8.8.8
Tracing route to dns.google [8.8.8.8]
over a maximum of 30 hops:
1 5 ms 1 ms 1 ms ralink.ralinktech.com [192.168.0.1]
2 * * * Request timed out.
3 * * * Request timed out.
4 * * * Request timed out.
5 * * * Request timed out.
6 41 ms 41 ms 42 ms dh120-129.xnet.hr [83.139.120.129]
7 34 ms 38 ms 38 ms ae72.edge1.Zagreb1.Level3.net [213.19.207.81]
8 52 ms 49 ms 44 ms ae2.3201.ear1.sof5.neo.colt.net [171.75.8.57]
9 36 ms 36 ms 37 ms 173.194.121.16
10 37 ms 35 ms 40 ms 216.239.59.239
11 52 ms 37 ms 40 ms 72.14.237.137
12 45 ms 47 ms 37 ms dns.google [8.8.8.8]
Trace complete.
```
#### Linux/macOS
```shell
$traceroute 8.8.8.8
traceroute to 8.8.8.8 (8.8.8.8), 30 hops max, 46 byte packets
1 konj (172.28.208.1) 0.483 ms 0.386 ms 0.272 ms
2 ralink.ralinktech.com (192.168.0.1) 0.913 ms 1.258 ms 0.929 ms
3 * * *
4 * * *
5 * * *
6 * * *
7 dh120-17.xnet.hr (83.139.120.17) 164.752 ms dh120-129.xnet.hr (83.139.120.129) 31.661 ms 27.350 ms
8 ae72.edge1.Zagreb1.Level3.net (213.19.207.81) 37.870 ms * 27.178 ms
9 ae2.3201.ear1.sof5.neo.colt.net (171.75.8.57) 35.631 ms lag25-9070.as8447.a1.net (195.3.64.141) 46.328 ms 29.935 ms
10 lag1-9073.as8447.a1.net (195.3.64.150) 40.241 ms 58.784 ms 173.194.121.16 (173.194.121.16) 46.641 ms
11 * * *
12 * * *
13 dns.google (8.8.8.8) 42.912 ms 43.369 ms 45.812 ms
```
### 3. Portovi i aplikacije
- Provjeri otvorene portove na računalu.
#### Windows
```bat
netstat -an
Active Connections
Proto Local Address Foreign Address State
... ... ... ...
TCP 0.0.0.0:445 0.0.0.0:0 LISTENING
TCP 0.0.0.0:902 0.0.0.0:0 LISTENING
TCP 192.168.0.100:54937 98.66.133.185:443 ESTABLISHED
TCP 192.168.0.100:57830 142.251.39.37:443 ESTABLISHED
TCP 192.168.0.100:57852 104.18.32.47:443 TIME_WAIT
TCP 192.168.0.100:57986 172.64.152.233:443 ESTABLISHED
TCP 192.168.0.100:59424 2.22.89.16:443 ESTABLISHED
TCP 192.168.0.100:59448 88.221.92.137:443 CLOSE_WAIT
TCP 192.168.0.100:59496 98.66.133.186:443 ESTABLISHED
TCP 192.168.0.100:59665 13.107.138.10:443 ESTABLISHED
TCP 192.168.0.100:59667 52.110.4.129:443 TIME_WAIT
TCP 192.168.0.100:59669 52.110.4.129:443 TIME_WAIT
TCP 192.168.0.100:59670 199.232.18.172:80 TIME_WAIT
TCP 192.168.0.100:59674 20.189.173.26:443 TIME_WAIT
TCP 192.168.0.100:59677 199.232.18.172:80 ESTABLISHED
TCP 192.168.0.100:59682 134.33.185.96:443 TIME_WAIT
TCP 192.168.0.100:59683 2.16.16.146:80 TIME_WAIT
UDP 0.0.0.0:53 *:*
UDP 0.0.0.0:53 *:*
UDP 0.0.0.0:500 *:*
UDP 0.0.0.0:4500 *:*
UDP 0.0.0.0:5050 *:*
UDP 0.0.0.0:5353 *:*
UDP 0.0.0.0:5353 *:*
UDP 0.0.0.0:5353 *:*
UDP 0.0.0.0:5353 *:*
UDP 0.0.0.0:5353 *:*
... ... ... ...
```
#### Linux/macOS
```shell
$ss -tuln
Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port
udp UNCONN 0 0 0.0.0.0:68 0.0.0.0:*
udp UNCONN 0 0 0.0.0.0:5353 0.0.0.0:*
tcp LISTEN 0 128 0.0.0.0:22 0.0.0.0:*
tcp LISTEN 0 128 [::]:22 [::]:*
```
#### Windows
### 4. IPv4 i subnetiranje
U ovom dijelu vježbe radimo s IPv4 adresama, maskama i subnetima.
Cilj je razumjeti kako se iz IP adrese i maske dobiju mrežna adresa, broadcast i raspon hostova.
---
#### 4.1 Pretvorba binarnog u dekadski zapis
Pretvori sljedeću IPv4 adresu iz binarnog u dekadski zapis:
```
10101100.00010000.00001010.00000101
```
**Kako:**
1. Podijeli zapis na 4 okteta (8 bita svaki).
2. Pretvori svaki oktet u decimalni broj.
3. Zapiši adresu u obliku `a.b.c.d`.
**Primjer:**
10101100 = 172
00010000 = 16
00001010 = 10
00000101 = 5
IPv4 adresa = ****
---
#### 4.2 Pronalaženje mrežne i broadcast adrese
Za zadanu adresu `10.0.5.42/24` izračunaj:
- mrežnu adresu
- broadcast adresu
- raspon hostova
- broj hostova u mreži
**Kako:**
1. Napiši adresu i masku `/24` (255.255.255.0) u binarnom obliku.
2. Primijeni logičku operaciju **AND** između IP adrese i maske → mrežna adresa.
3. Broadcast dobiješ kada sve host bitove postaviš na `1`.
4. Raspon hostova su sve adrese između mrežne i broadcast adrese.
5. Broj hostova = `2^(broj host bitova) - 2`.
**Primjer:**
- IP: 10.0.5.42 = `00001010.00000000.00000101.00101010`
- Maska: 255.255.255.0 = `11111111.11111111.11111111.00000000`
- Mreža: `00001010.00000000.00000101.00000000` = **10.0.5.0**
- Broadcast: `00001010.00000000.00000101.11111111` = **10.0.5.255**
- Raspon hostova: **10.0.5.1 – 10.0.5.254**
- Broj hostova: 254
---
#### 4.3 Subnetiranje mreže
Podijeli mrežu `172.16.8.0/24` na **4 podmreže**.
**Kako:**
1. `/24` = 256 adresa (254 hosta).
2. Treba 4 podmreže → nova maska `/26` (255.255.255.192).
3. Svaka podmreža ima 64 adrese (62 hosta).
4. Računaj mrežne adrese u koracima od 64.
**Primjer:**
- 1. podmreža: **172.16.8.0 – 172.16.8.63** (hostovi 172.16.8.1 – 172.16.8.62)
- 2. podmreža: **172.16.8.64 – 172.16.8.127** (hostovi 172.16.8.65 – 172.16.8.126)
- 3. podmreža: **172.16.8.128 – 172.16.8.191** (hostovi 172.16.8.129 – 172.16.8.190)
- 4. podmreža: **172.16.8.192 – 172.16.8.255** (hostovi 172.16.8.193 – 172.16.8.254)
---
#### 4.4 Binarni prikaz maske
Prikaži masku `/24` u binarnom obliku i objasni koliko adresa daje.
**Kako:**
1. `/24` znači da 24 bita pripada mrežnom dijelu, a 8 bitova host dijelu.
2. Zapiši binarno:
11111111.11111111.11111111.00000000
3. Broj host adresa = 2^8 = 256.
4. Oduzmi 2 (mrežna i broadcast).
**Primjer:**
- Ukupno adresa: 256
- Korisne za hostove: **254**
---
#### 4.5 Privatne i javne adrese
Provjeri sljedeće adrese i odredi jesu li privatne ili javne:
- 172.20.5.10
- 8.8.8.8
- 192.168.100.25
**Kako:**
1. Usporedi adrese s rasponima privatnih mreža:
- 10.0.0.0 – 10.255.255.255 (/8)
- 172.16.0.0 – 172.31.255.255 (/12)
- 192.168.0.0 – 192.168.255.255 (/16)
2. Ako se adresa nalazi unutar tih raspona → privatna. Ako ne → javna.
**Primjer:**
- 172.20.5.10 → privatna (u rasponu 172.16 – 172.31)
- 8.8.8.8 → javna (Google DNS)
- 192.168.100.25 → privatna (u rasponu 192.168.0.0 – 192.168.255.255)
### 5. IPv6 osnove i subnetiranje
U ovom dijelu vježbe radiš s IPv6 adresama, njihovim tipovima i subnetima.
Cilj je razumjeti osnovne vrste IPv6 adresa, zapis i način subnetiranja.
---
#### 5.1 Struktura IPv6 adrese
IPv6 adresa ima **128 bitova**, zapisana u **8 grupa po 16 bitova** (heksadecimalno).
Primjer pune adrese:
2001:0db8:0000:0000:0000:0000:0000:0001
**Kako skratiti zapis:**
1. Ukloni vodeće nule u svakoj grupi.
2. Jedanput u adresi možeš zamijeniti uzastopne grupe nula s `::`.
**Primjer:**
2001:0db8:0000:0000:0000:0000:0000:0001
= 2001:db8:0:0:0:0:0:1
= 2001:db8::1
---
#### 5.2 Vrste IPv6 adresa
1. **Link-local** — uvijek prisutne na svakom interfejsu (`fe80::/10`).
- Koriste se za lokalnu komunikaciju u istom segmentu.
- Primjer: `fe80::1a2b:3c4d:5e6f:7a8b%eth0`
2. **Global unicast** — javne IPv6 adrese (`2000::/3`).
- Koriste se na Internetu.
- Primjer: `2001:db8::1234`
3. **Multicast** — adrese za grupnu komunikaciju (`ff00::/8`).
- Primjer: `ff02::1` (svi čvorovi na lokalnom linku).
---
#### 5.3 Subnetiranje u IPv6
Subnetiranje funkcionira isto kao u IPv4, ali se koristi **CIDR zapis** (npr. `/32`, `/48`, `/64`).
**Najčešći primjeri u praksi:**
- `/32` → ISP dobiva veliki blok.
- `/48` → organizaciji dodijeljen prostor.
- `/64` → standardni subnet za jedan LAN segment.
- `/128` → jedna jedina adresa (npr. za točno jedan uređaj).
**Primjer:**
2001:db8:abbd:1233::/64
- Mreža: `2001:db8:abcd:1234::`
- Host dio: zadnjih 64 bita (≈ 1.8 × 10^19 adresa).
---
#### 5.4 Primjer vježbe s IPv6 adresom
Zadano:
IPv6 adresa: fe80::5abd:2efe:1a11:1a7c%16
1. Prepoznaj da počinje s `fe80::` → znači da je **link-local**.
2. `%16` označava **interface index** (na kojem interfejsu vrijedi ta adresa).
3. Pokušaj pingati ovu adresu (Linux/macOS):
```bash
ping6 fe80::5abd:2efe:1a11:1a7c%eth0
```
4. Ako je uspješno, dobit ćeš odgovore s tog interfejsa.
#### 5.5 Zašto /64?
IPv6 autokonfiguracija (SLAAC) radi samo s maskom /64.
Standard je da svaki LAN segment koristi /64.
To znači da svaki subnet ima 2^64 adresa (praktički neiscrpno).
Primjer:
Mreža: 2001:db8:abbd:1233::/64
Prvi host: 2001:db8:abbd:1233::1
Drugi host: 2001:db8:abbd:1233::2
...
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