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Computer Architecture and Operating Systems

Course taught at Faculty of Computer Science of Higher School of Economics

Lecture 12

Basics of Networking

Lecture

Slides (PDF, PPTX).

Workshop

Using the wget utility to download files (via HTTPS):

wget https://andrewt0301.github.io/hse-acos-course/part2os/12_Networking/OS_Lecture_12.pdf
--2025-06-01 23:01:58--  https://andrewt0301.github.io/hse-acos-course/part2os/12_Networking/OS_Lecture_12.pdf
Resolving andrewt0301.github.io (andrewt0301.github.io)... 185.199.110.153, 185.199.111.153, 185.199.108.153, ...
Connecting to andrewt0301.github.io (andrewt0301.github.io)|185.199.110.153|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1338083 (1.3M) [application/pdf]
Saving to: ‘OS_Lecture_12.pdf’

OS_Lecture_12.pdf                         100%[====================================================================================>]   1.28M   801KB/s    in 1.6s    

2025-06-01 23:02:00 (801 KB/s) - ‘OS_Lecture_12.pdf’ saved [1338083/1338083]

Using the curl utility to download files (via HTTPS):

curl https://andrewt0301.github.io/hse-acos-course/part2os/12_Networking/OS_Lecture_12.pdf -O
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 1306k  100 1306k    0     0  1008k      0  0:00:01  0:00:01 --:--:-- 1008k

Viewing standard ports for various services:

cat /etc/services | grep http
# Updated from https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml .
http		80/tcp		www		# WorldWideWeb HTTP
https		443/tcp				# http protocol over TLS/SSL
https		443/udp				# HTTP/3
http-alt	8080/tcp	webcache	# WWW caching service

Viewing/editing the /etc/hosts file:

cat /etc/hosts
127.0.0.1	localhost
127.0.1.1	huawei-ThinkPad-T490s
158.160.144.239	ejudge

# The following lines are desirable for IPv6 capable hosts
::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

Querying DNS with nslookup:

nslookup hse.ru
Server:		127.0.0.53
Address:	127.0.0.53#53

Non-authoritative answer:
Name:	hse.ru
Address: 178.248.234.104

Querying information on an IP address with whois:

whois 89.175.46.44
% This is the RIPE Database query service.
% The objects are in RPSL format.
%
% The RIPE Database is subject to Terms and Conditions.
% See https://docs.db.ripe.net/terms-conditions.html

% Note: this output has been filtered.
%       To receive output for a database update, use the "-B" flag.

% Information related to '89.175.46.0 - 89.175.46.255'

% Abuse contact for '89.175.46.0 - 89.175.46.255' is 'abuse@mtu.ru'

inetnum:        89.175.46.0 - 89.175.46.255
netname:        NRUHSE
descr:          National Research University Higher School of Economics
country:        RU
admin-c:        MTU1-RIPE
tech-c:         MTU1-RIPE
status:         ASSIGNED PA
mnt-by:         MTU-NOC
created:        2022-02-04T07:55:18Z
last-modified:  2022-02-04T07:55:18Z
source:         RIPE

role:           MTS backbone NOC
address:        PJSC MTS / former CJSC Comstar-Direct
address:        Petrovsky blvd 12, bldg 3
address:        P.O. BOX 4711 127051
address:        Moscow, Russia
remarks:        **************************************
remarks:        Contact addresses:
remarks:        routing & peering noc@mtu.ru
remarks:        spam & security abuse@mtu.ru
remarks:        mail postmaster@mtu.ru
remarks:        ddos reports ddos-reports@mtu.ru
remarks:        **************************************
phone:          +7 495 721-34-99
fax-no:         +7 495 956-07-07
admin-c:        EDA-RIPE
admin-c:        RPS-RIPE
tech-c:         EDA-RIPE
nic-hdl:        MTU1-RIPE
mnt-by:         MTU-NOC
created:        2002-10-18T13:29:19Z
last-modified:  2022-04-08T13:50:05Z
source:         RIPE # Filtered

% Information related to '89.175.0.0/16AS8359'

route:          89.175.0.0/16
descr:          MTS PJSC
origin:         AS8359
mnt-by:         MTU-NOC
created:        2016-06-04T18:36:17Z
last-modified:  2024-06-06T12:06:50Z
source:         RIPE # Filtered

% This query was served by the RIPE Database Query Service version 1.117 (DEXTER)

Analyze TCP packets with the tcpdump tool:

sudo tcpdump host 158.160.144.239 -v

Homework

TODO

References