reading:
notes from various readings:
https://blog.cloudflare.com/why-google-went-offline-today-and-a-bit-about/:
- google has a public dns server: 8.8.8.8
- looked at
dig. it basically does a lookup from dns. so i can give an ip (or a web address), and it should resolve the dns and send it to me.
interestingly, if you query the name:
a@10-20-81-185 ~ % dig https://dns.google
; <<>> DiG 9.10.6 <<>> https://dns.google
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 4017
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1220
;; QUESTION SECTION:
;https://dns.google. IN A
;; AUTHORITY SECTION:
google. 300 IN SOA ns-tld1.charlestonroadregistry.com. cloud-dns-hostmaster.google.com. 1 21600 3600 259200 900
;; Query time: 51 msec
;; SERVER: 128.122.0.11#53(128.122.0.11)
;; WHEN: Sat Sep 12 11:45:42 EDT 2026
;; MSG SIZE rcvd: 145
a@10-20-81-185 ~ %
you get 145 bytes (i believe).
but if you query the address:
a@10-20-81-185 ~ % dig 8.8.8.8
; <<>> DiG 9.10.6 <<>> 8.8.8.8
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 15637
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1220
;; QUESTION SECTION:
;8.8.8.8. IN A
;; AUTHORITY SECTION:
. 189 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2026091200 1800 900 604800 86400
;; Query time: 10 msec
;; SERVER: 128.122.0.11#53(128.122.0.11)
;; WHEN: Sat Sep 12 11:39:49 EDT 2026
;; MSG SIZE rcvd: 111
you get 111 bytes. but actually i’m querying the same server 128.122.0.11#53(128.122.0.11). i assume # is port. i don’t know.
and if i query the exact address that the server is on:
a@10-20-81-185 ~ % dig 128.122.0.11
; <<>> DiG 9.10.6 <<>> 128.122.0.11
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 15930
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1220
;; QUESTION SECTION:
;128.122.0.11. IN A
;; AUTHORITY SECTION:
. 46 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2026091200 1800 900 604800 86400
;; Query time: 7 msec
;; SERVER: 128.122.0.11#53(128.122.0.11)
;; WHEN: Sat Sep 12 11:46:34 EDT 2026
;; MSG SIZE rcvd: 116
i then looked into dig and realized i was stupid. dig does a lookup of a domain basically. and you can specify the domain name and where it needs to do the lookup.
so, like for my domain:
a@10-20-81-185 ~ % dig @8.8.8.8 arjunmakesthings.github.io
; <<>> DiG 9.10.6 <<>> @8.8.8.8 arjunmakesthings.github.io
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 5998
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;arjunmakesthings.github.io. IN A
;; ANSWER SECTION:
arjunmakesthings.github.io. 3600 IN A 185.199.108.153
arjunmakesthings.github.io. 3600 IN A 185.199.110.153
arjunmakesthings.github.io. 3600 IN A 185.199.111.153
arjunmakesthings.github.io. 3600 IN A 185.199.109.153
;; Query time: 141 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Sat Sep 12 11:48:46 EDT 2026
;; MSG SIZE rcvd: 119
all of those ips were owned by github.com, but did not serve my website. so, i tried with tom’s.
so, all of these ips that are provided with the dns lookup are not reachable by the browser for some reason. i don’t know why.
but this digcommand is helpful to figure out where something is hosted. for example, for cody’s website, i can tell it’s hosted on amazon by looking at this (and i can confirm because i know he uses aws).
a@10-20-81-185 ~ % dig https://www.ccfrost.com
; <<>> DiG 9.10.6 <<>> https://www.ccfrost.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 11060
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1220
;; QUESTION SECTION:
;https://www.ccfrost.com. IN A
;; AUTHORITY SECTION:
ccfrost.com. 300 IN SOA ns-27.awsdns-03.com. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
;; Query time: 49 msec
;; SERVER: 128.122.0.11#53(128.122.0.11)
;; WHEN: Sat Sep 12 11:54:11 EDT 2026
;; MSG SIZE rcvd: 129
a@10-20-81-185 ~ %
actually, aws doesn’t even give me an ip for some reason.
ah that was because i used https. i just need to search for the domain. when i did that, i got:
a@10-20-81-185 ~ % dig ccfrost.com
; <<>> DiG 9.10.6 <<>> ccfrost.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 36187
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1220
;; QUESTION SECTION:
;ccfrost.com. IN A
;; ANSWER SECTION:
ccfrost.com. 60 IN A 13.33.67.7
ccfrost.com. 60 IN A 13.33.67.12
ccfrost.com. 60 IN A 13.33.67.71
ccfrost.com. 60 IN A 13.33.67.82
;; Query time: 21 msec
;; SERVER: 128.122.0.11#53(128.122.0.11)
;; WHEN: Sat Sep 12 11:55:49 EDT 2026
;; MSG SIZE rcvd: 104
then, if i ping his domain, i can tell which one serves the webpages publicly:
ccfrost.com. 60 IN A 13.33.67.7
ccfrost.com. 60 IN A 13.33.67.12
ccfrost.com. 60 IN A 13.33.67.71
ccfrost.com. 60 IN A 13.33.67.82
;; Query time: 21 msec
;; SERVER: 128.122.0.11#53(128.122.0.11)
;; WHEN: Sat Sep 12 11:55:49 EDT 2026
;; MSG SIZE rcvd: 104
a@10-20-81-185 ~ % ping ccfrost.com
PING ccfrost.com (13.33.67.12): 56 data bytes
64 bytes from 13.33.67.12: icmp_seq=0 ttl=242 time=6.966 ms
64 bytes from 13.33.67.12: icmp_seq=1 ttl=242 time=10.408 ms
64 bytes from 13.33.67.12: icmp_seq=2 ttl=242 time=23.395 ms
64 bytes from 13.33.67.12: icmp_seq=3 ttl=242 time=60.249 ms
64 bytes from 13.33.67.12: icmp_seq=4 ttl=242 time=101.177 ms
^C
--- ccfrost.com ping statistics ---
5 packets transmitted, 5 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 6.966/40.439/101.177/35.761 ms
a@10-20-81-185 ~ %
so, it was: 13.33.67.12. but if i go to that ip, i get nothing.
anyway; more notes from the reading:
- each network has a unique number ‘as’ number.
i tried finding the as number that i was a part of, but couldn’t. it showed no matches.
then, i realized that the mac does something interesting. for each network, you can choose between a fixed (random) mac address or a rotating one (perhaps to prevent being spoofed).
i realized this because my ifconfig for one network was something, and another for something else.
on my raspberry-pi, however, my address remains the same.
anyways:
- each network has an as number.
- as-s are connected by bgp (border gateway protocol) — ip → ip → ip and telling what ip is what network.
- if anyone in the bgp says hey i’m this ip (which is in another as), the bgp trusts it and sends it to the as.
the other readings were short & put things into perspective. i don’t have many notes about that.
ask:
i didn’t successfully make one in the first time. my ssh authentication was not working. james & i tried using the verbose mode to figure out what was happening, but we couldn’t. so i just did the whole thing again.
got it the second time. you can also make it ssh using keys that are not in the ~/.ssh/directory with ssh -i <filepath ~>.
when i locked my root password, i realized that user didn't have access to sudo controls.
so, i had to log-in as root from the webconsole, and run this:
sudo usermod -aG sudo <username>then i was able to sudo with my non-root id.
got firewall:
non-root@arjun-und-net:~$ sudo ufw enable
Command may disrupt existing ssh connections. Proceed with operation (y|n)? y
Firewall is active and enabled on system startup
need to read this: https://itp.nyu.edu/networks/setting-up-a-firewall-on-an-embedded-linux-device/
watched this: https://vimeo.com/457083868 for firewall log detection.
- ssh runs on port 22
- web server operates on 80 & 443.
these are my firewall logs:
2026-09-13T01:20:00.517334+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=176.65.134.24 DST=167.99.147.44 LEN=76 TOS=0x00 PREC=0x00 TTL=246 ID=54321 PROTO=UDP SPT=43838 DPT=123 LEN=56
2026-09-13T01:20:14.724817+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=74.82.47.19 DST=167.99.147.44 LEN=40 TOS=0x00 PREC=0x00 TTL=242 ID=54321 PROTO=TCP SPT=40551 DPT=81 WINDOW=65535 RES=0x00 SYN URGP=0
2026-09-13T01:20:14.805176+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=77.239.124.128 DST=167.99.147.44 LEN=40 TOS=0x00 PREC=0x00 TTL=247 ID=54321 PROTO=TCP SPT=55840 DPT=8088 WINDOW=65535 RES=0x00 SYN URGP=0
2026-09-13T01:20:15.905984+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=85.217.140.52 DST=167.99.147.44 LEN=52 TOS=0x00 PREC=0x00 TTL=52 ID=58354 PROTO=TCP SPT=33004 DPT=18144 WINDOW=65535 RES=0x00 SYN URGP=0
2026-09-13T01:20:21.153937+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=176.65.134.52 DST=167.99.147.44 LEN=44 TOS=0x00 PREC=0x00 TTL=245 ID=27347 PROTO=TCP SPT=61000 DPT=25567 WINDOW=1025 RES=0x00 SYN URGP=0
2026-09-13T01:20:23.427965+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=45.33.46.249 DST=167.99.147.44 LEN=40 TOS=0x00 PREC=0x00 TTL=240 ID=54321 PROTO=TCP SPT=41173 DPT=53 WINDOW=65535 RES=0x00 SYN URGP=0
2026-09-13T01:20:24.931985+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=85.217.149.71 DST=167.99.147.44 LEN=52 TOS=0x00 PREC=0x00 TTL=53 ID=1586 PROTO=TCP SPT=55598 DPT=16279 WINDOW=65535 RES=0x00 SYN URGP=0
2026-09-13T01:20:34.624916+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=136.60.47.95 DST=167.99.147.44 LEN=64 TOS=0x00 PREC=0x00 TTL=53 ID=0 DF PROTO=TCP SPT=50782 DPT=56495 WINDOW=8192 RES=0x00 SYN URGP=0
2026-09-13T01:20:35.380316+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=198.235.24.197 DST=167.99.147.44 LEN=44 TOS=0x00 PREC=0x00 TTL=249 ID=54321 PROTO=TCP SPT=55421 DPT=20121 WINDOW=65535 RES=0x00 SYN URGP=0
2026-09-13T01:20:35.625660+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=136.60.47.95 DST=167.99.147.44 LEN=64 TOS=0x00 PREC=0x00 TTL=53 ID=0 DF PROTO=TCP SPT=50782 DPT=56495 WINDOW=8192 RES=0x00 SYN URGP=0
2026-09-13T01:20:36.547685+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=136.60.47.95 DST=167.99.147.44 LEN=64 TOS=0x00 PREC=0x00 TTL=53 ID=0 DF PROTO=TCP SPT=50788 DPT=56495 WINDOW=8192 RES=0x00 SYN URGP=0
2026-09-13T01:20:48.147294+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=147.185.132.42 DST=167.99.147.44 LEN=44 TOS=0x00 PREC=0x00 TTL=247 ID=54321 PROTO=TCP SPT=53989 DPT=7170 WINDOW=65535 RES=0x00 SYN URGP=0
2026-09-13T01:21:00.826067+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=37.221.195.225 DST=167.99.147.44 LEN=60 TOS=0x00 PREC=0x00 TTL=56 ID=30446 DF PROTO=TCP SPT=64204 DPT=8443 WINDOW=42340 RES=0x00 SYN URGP=0
2026-09-13T01:21:22.337694+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=20.150.197.110 DST=167.99.147.44 LEN=52 TOS=0x00 PREC=0x00 TTL=44 ID=44356 PROTO=TCP SPT=33020 DPT=8040 WINDOW=65535 RES=0x00 SYN URGP=0
2026-09-13T01:21:40.616923+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=66.132.186.246 DST=167.99.147.44 LEN=60 TOS=0x00 PREC=0x00 TTL=57 ID=24343 PROTO=TCP SPT=37261 DPT=22822 WINDOW=42340 RES=0x00 SYN URGP=0
2026-09-13T01:22:10.791473+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=172.94.9.39 DST=167.99.147.44 LEN=44 TOS=0x00 PREC=0x00 TTL=247 ID=59516 PROTO=TCP SPT=56207 DPT=3355 WINDOW=1025 RES=0x00 SYN URGP=0
2026-09-13T01:22:24.117265+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=162.216.149.103 DST=167.99.147.44 LEN=44 TOS=0x00 PREC=0x00 TTL=247 ID=54321 PROTO=TCP SPT=52137 DPT=9859 WINDOW=65535 RES=0x00 SYN URGP=0
2026-09-13T01:22:41.191256+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=77.239.124.128 DST=167.99.147.44 LEN=40 TOS=0x00 PREC=0x00 TTL=247 ID=54321 PROTO=TCP SPT=39602 DPT=8088 WINDOW=65535 RES=0x00 SYN URGP=0
2026-09-13T01:23:09.955026+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=194.187.176.111 DST=167.99.147.44 LEN=44 TOS=0x08 PREC=0x20 TTL=241 ID=16533 DF PROTO=TCP SPT=63826 DPT=8991 WINDOW=8192 RES=0x00 SYN URGP=0
2026-09-13T01:23:22.934838+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=66.132.172.114 DST=167.99.147.44 LEN=60 TOS=0x00 PREC=0x00 TTL=56 ID=16930 PROTO=TCP SPT=58358 DPT=17988 WINDOW=42340 RES=0x00 SYN URGP=0
2026-09-13T01:23:41.827432+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=31.220.3.165 DST=167.99.147.44 LEN=40 TOS=0x08 PREC=0x20 TTL=53 ID=27587 PROTO=TCP SPT=35842 DPT=23 WINDOW=41258 RES=0x00 SYN URGP=0
2026-09-13T01:24:01.163027+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=64.89.163.83 DST=167.99.147.44 LEN=44 TOS=0x08 PREC=0x20 TTL=241 ID=28808 PROTO=TCP SPT=42459 DPT=5432 WINDOW=1025 RES=0x00 SYN URGP=0
2026-09-13T01:24:26.549486+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=185.139.214.221 DST=167.99.147.44 LEN=40 TOS=0x08 PREC=0x20 TTL=241 ID=59463 PROTO=TCP SPT=58626 DPT=21 WINDOW=1024 RES=0x00 SYN URGP=0
2026-09-13T01:24:42.058411+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=69.12.71.34 DST=167.99.147.44 LEN=40 TOS=0x08 PREC=0x40 TTL=241 ID=54321 PROTO=TCP SPT=38104 DPT=9200 WINDOW=65535 RES=0x00 SYN URGP=0
2026-09-13T01:25:14.649801+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=167.94.146.76 DST=167.99.147.44 LEN=60 TOS=0x08 PREC=0x40 TTL=50 ID=5228 PROTO=TCP SPT=59772 DPT=61793 WINDOW=42340 RES=0x00 SYN URGP=0
2026-09-13T01:25:24.206819+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=85.217.140.2 DST=167.99.147.44 LEN=52 TOS=0x00 PREC=0x00 TTL=51 ID=50766 PROTO=TCP SPT=58502 DPT=7080 WINDOW=65535 RES=0x00 SYN URGP=0
2026-09-13T01:25:47.433371+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=45.79.67.140 DST=167.99.147.44 LEN=40 TOS=0x00 PREC=0x00 TTL=240 ID=54321 PROTO=TCP SPT=52590 DPT=3128 WINDOW=65535 RES=0x00 SYN URGP=0
2026-09-13T01:26:03.710187+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=91.231.89.66 DST=167.99.147.44 LEN=60 TOS=0x00 PREC=0x00 TTL=52 ID=37825 DF PROTO=TCP SPT=46319 DPT=7673 WINDOW=5840 RES=0x00 SYN URGP=0
2026-09-13T01:26:22.412939+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=116.98.50.77 DST=167.99.147.44 LEN=60 TOS=0x00 PREC=0x00 TTL=47 ID=24590 DF PROTO=TCP SPT=55110 DPT=23 WINDOW=65340 RES=0x00 SYN URGP=0
2026-09-13T01:26:49.803901+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=185.73.23.133 DST=167.99.147.44 LEN=52 TOS=0x00 PREC=0x00 TTL=49 ID=31434 PROTO=TCP SPT=47292 DPT=1883 WINDOW=65535 RES=0x00 SYN URGP=0
2026-09-13T01:27:00.546389+00:00 arjun-und-net kernel: [UFW BLOCK] IN=eth0 OUT= MAC=16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00 SRC=85.217.149.70 DST=167.99.147.44 LEN=52 TOS=0x00 PREC=0x00 TTL=53 ID=25051 PROTO=TCP SPT=35690 DPT=27742 WINDOW=65535 RES=0x00 SYN URGP=0all of them are actually from this mac address:
16:c2:4a:12:1c:49:fe:00:00:00:01:01:08:00no assignment was found for this mac address.