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 --:--:-- 1008kViewing 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 serviceViewing/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-allroutersQuerying DNS with nslookup:
nslookup hse.ru
Server: 127.0.0.53
Address: 127.0.0.53#53
Non-authoritative answer:
Name: hse.ru
Address: 178.248.234.104Querying 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 -vTODO