- Uporabite omrežje in navidezne računalnike iz 2. vaje.
- Namestite program Wireshark in zajemite ter preglejte pakete iz naslednjih nalog.
- Namestite Trivial File Transport Protocol (TFTP) strežnik in preko njega prenesite datoteko na drug navidezni računalnik.
- Namestite Hypertext Transfer Protocol (HTTP) strežnik in preko njega prenesite datoteko na drug navidezni računalnik.
- Primerjajte hitrost prenosa datoteke med protokoloma TFTP in HTTP.
Ukaz usermod nam omogoča spreminjanje lastnosti računa uporabnika.
Ukaz dpkg nam omogoča upravljanje s paketi operacijskega sistema Debian.
Ukaz systemctl nam omogoča upravljanje systemd sistema in storitev operacijskega sistema.
Ukaz wget predstavlja orodje za prenos datotek preko omrežja s protokoli HTTP, HTTPS in FTP.
Ukaz netstat predstavlja orodje za prikaz omrežnih lastnosti računalnika in storitev.
Ukaz cp nam omogoča kopiranje datotek in map od izvora k ponoru.
Sedaj namestimo program za zajemanje paketkov na omrežju Wireshark preko upravljalca paketkov našega operacijskega sistema.
apt install wireshark
Med namestitvijo se nam pojavi naslednja izbira:
Dumpcap can be installed in a way that allows members of the "wireshark" system group to capture packets. This is recommended over the alternative of running Wireshark/Tshark directly as root, because less of the code will run with elevated privileges.
For more detailed information please see /usr/share/doc/wireshark-common/README.Debian.gz once the package is installed.
Enabling this feature may be a security risk, so it is disabled by default. If in doubt, it is suggested to leave it disabled.
Should non-superusers be able to capture packets?
<Yes> <No>
Kjer izberemo možnost Da, in potem dodamo našega uporabnika v skupino wireshark, da mu omogočim dostop do zajemanja prometa na omrežnih karticah z ukazom usermod.
usermod -a -G wireshark YOUR_USERNAME
V primeru, da ste izbrali možnost Ne, lahko ponovno prikličete nastavitev z ukazom dpkg-reconfigure.
sudo dpkg-reconfigure wireshark-common
Sedaj ponovno poženemo navidezni računalnik in poženemo Wireshark, da spremlja promet na omrežni kartici enp0s8.
Na strežniku namestimo željeno implementacijo TFTP strežnika, na primer tftpd-hpa preko upravljalca paketkov našega operacijskega sistema.
apt install tftpd-hpa
Nastavitve TFTP strežnika preverimo v nastavitveni datoteki /etc/default/tftpd-hpa, kjer nastavimo mapo, ki jo strežnik ponuja prek omrežja.
nano /etc/default/tftpd-hpa
# /etc/default/tftpd-hpa
TFTP_USERNAME="tftp"
TFTP_DIRECTORY="/srv/tftp"
TFTP_ADDRESS=":69"
TFTP_OPTIONS="--secure"
Delovanje strežnika preverimo z ukazom systemctl:
systemctl status tftpd-hpa.service
V mapi /srv/tftp ustvarimo poljubno datoteko, na primer:
nano /srv/tftp/test.txt
This is a test file.
Na klientu sedaj namestimo TFTP klienta preko upravljalca paketkov našega operacijskega sistema, da preverimo delovanje TFTP protokola s prenosom ustvarjene datoteke.
apt install tftp-hpa
tftp
(to) 10.0.1.1
tftp> get test.txt
tftp> quit
cat test.txt
Na strežniku namestimo željeno implementacijo HTTP strežnika, na primer lighttpd preko upravljalca paketkov našega operacijskega sistema.
apt install lighttpd
Nastavitve HTTP strežnika preverimo v nastavitveni datoteki /etc/lighttpd/lighttpd.conf, kjer nastavimo mapo, ki jo strežnik ponuja prek omrežja.
server.modules = (
"mod_indexfile",
"mod_access",
"mod_alias",
"mod_redirect",
)
server.document-root = "/var/www/html"
server.upload-dirs = ( "/var/cache/lighttpd/uploads" )
server.errorlog = "/var/log/lighttpd/error.log"
server.pid-file = "/run/lighttpd.pid"
server.username = "www-data"
server.groupname = "www-data"
server.port = 80
# features
#https://redmine.lighttpd.net/projects/lighttpd/wiki/Server_feature-flagsDetails
server.feature-flags += ("server.h2proto" => "enable")
server.feature-flags += ("server.h2c" => "enable")
server.feature-flags += ("server.graceful-shutdown-timeout" => 5)
#server.feature-flags += ("server.graceful-restart-bg" => "enable")
# strict parsing and normalization of URL for consistency and security
# https://redmine.lighttpd.net/projects/lighttpd/wiki/Server_http-parseoptsDetails
# (might need to explicitly set "url-path-2f-decode" = "disable"
# if a specific application is encoding URLs inside url-path)
server.http-parseopts = (
"header-strict" => "enable",# default
"host-strict" => "enable",# default
"host-normalize" => "enable",# default
"url-normalize-unreserved"=> "enable",# recommended highly
"url-normalize-required" => "enable",# recommended
"url-ctrls-reject" => "enable",# recommended
"url-path-2f-decode" => "enable",# recommended highly (unless breaks app)
#"url-path-2f-reject" => "enable",
"url-path-dotseg-remove" => "enable",# recommended highly (unless breaks app)
#"url-path-dotseg-reject" => "enable",
#"url-query-20-plus" => "enable",# consistency in query string
)
index-file.names = ( "index.php", "index.html" )
url.access-deny = ( "~", ".inc" )
static-file.exclude-extensions = ( ".php", ".pl", ".fcgi" )
# default listening port for IPv6 falls back to the IPv4 port
include_shell "/usr/share/lighttpd/use-ipv6.pl " + server.port
include_shell "/usr/share/lighttpd/create-mime.conf.pl"
include "/etc/lighttpd/conf-enabled/*.conf"
#server.compat-module-load = "disable"
server.modules += (
"mod_dirlisting",
"mod_staticfile",
)
V mapi /var/www/html ustvarimo poljubno datoteko, na primer:
nano /var/www/html/test.txt
This is a test file.
Na klientu sedaj z ukazom wget preverimo delovanje HTTP protokola s prenosom ustvarjene datoteke.
wget http://10.0.1.1/test.txt
--2024-10-18 15:53:56-- http://10.0.1.1/test.txt
Connecting to 10.0.1.1:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 12 [text/plain]
Saving to: ‘test.txt’
test.txt 100%[===================>] 12 --.-KB/s in 0s
2024-10-18 15:53:56 (2.30 MB/s) - ‘test.txt’ saved [12/12]
cat test.txt
Katere storitve trenutno tečejo na našem strežniku in na katerih vratih poslušajo lahko preverimo z orodjem netstat.
apt install net-tools
netstat -ntulp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign A ddress State PID/Program name
tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN 678/cupsd
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 3144/lighttpd
tcp6 0 0 ::1:631 :::* LISTEN 678/cupsd
tcp6 0 0 :::80 :::* LISTEN 3144/lighttpd
udp 0 0 0.0.0.0:35725 0.0.0.0:* 629/avahi-daemon: r
udp 0 0 0.0.0.0:5353 0.0.0.0:* 629/avahi-daemon: r
udp 0 0 0.0.0.0:67 0.0.0.0:* 707/dhcpd
udp 0 0 0.0.0.0:68 0.0.0.0:* 563/dhclient
udp 0 0 0.0.0.0:69 0.0.0.0:* 2741/in.tftpd
udp6 0 0 :::5353 :::* 629/avahi-daemon: r
udp6 0 0 :::42225 :::* 629/avahi-daemon: r
udp6 0 0 :::69 :::* 2741/in.tftpd
Sedaj prenesemo poljubno veliko datoteko s spleta na naš strežnik, na primer namestitveno sliko operacijskega sistema Mint ter jo kopiramo v mapi /srv/tftp in /var/www/html.
cp /home/aleks/Downloads/linuxmint-22-cinnamon-64bit.iso /srv/tftp/Mint.iso
cp /home/aleks/Downloads/linuxmint-22-cinnamon-64bit.iso /var/www/html/Mint.iso
Na strežniku sedaj z ukazom wget prenesemo omenjeno datoteko preko protokola HTTP.
wget http://10.0.1.1/Mint.iso
--2024-10-18 16:19:32-- http://10.0.1.1/Mint.iso
Connecting to 10.0.1.1:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 2907832320 (2.7G) [application/x-iso9660-image]
Saving to: ‘Mint.iso’
Mint.iso 100%[===================>] 2.71G 201MB/s in 14s
2024-10-18 16:19:47 (194 MB/s) - ‘Mint.iso’ saved [2907832320/2907832320]
Sedaj pa prenesemo enako datoteko še z ukazom tftp preko protokola TFTP.
tftp
(to) 10.0.1.1
tftp> verbose
Verbose mode on.
tftp> get Mint.iso
getting from 10.0.1.1:Mint.iso to Mint.iso [netascii]
Received 2930509229 bytes in 853.7 seconds [27462515 bit/s]
tftp> quit