Steven Almeroth

Code Of Honor

Prime Site Tech

Biography

Tropical Solar: Capricornus (♑) Cardinal Earth Sea-goat | The Sumerian Enki was the god of intelligence, creation, crafts, magic & water
Sidereal Solar: Sagittarius (♐) Mutable Fire Archer | The centaur of mythology, the learned healer whose higher intelligence forms a bridge between Earth and Heaven
Chinese: Wood Snake (蛇) Month: May Time: 9:00 to 11:00 a.m.

Interests

Living Honestly
Family Matters
Information Retrieval

Education

Colored Pill Revelations, 1965

School of Hard Knocks
BSc in Computer Science, 1988

University of Dayton

Skills

Python

2012

TypeScript

2020

Rust

2022

Contact

steven.almeroth@gmail.com
+1 216 666 0300
7387 Pine Ridge Ct, Cleveland, Ohio 44130
I-71 to Bagley Rd exit or Pearl Rd exit
Monday 10:00 to 13:00
Wednesday 09:00 to 10:00
DM Me
Skype Me
Telegram
Discuss on Forum

Git

Git commands

Forks

How to update a fork from the upstream branch

First add the upstream remote, let’s call it upstream. Then display it to make sure it took. Then fetch the code and rebase it into master. Finally push it up to the fork remote, probably origin.

$ git remote add upstream git@github.com:scrapinghub/varanus.git
$ git remote -v
$ git checkout master
$ git fetch upstream
$ git rebase upstream/master
$ git push

Ref Log

How to get back files from atomic actions

I’m saying “atomic actions” here to mean something that you told Git to do which is no longer in any of your branches we see in the normal log. The fact is that it might still available in the reflog.

Scenario: I made changes to two files which I committed in a single commit. I realized I wanted them to be in two separate commits so I reverted one of the file’s changes and merged it back into the commit. This as you may have guessed erased my changes to the second file.

To get the changes back from the second file I did:

$ git reflog

0442192 (HEAD -> stdhttp) HEAD@{1}: rebase (continue) (pick): TEMP: count index 0
c41e23b HEAD@{2}: rebase (continue) (fixup): f: server: gold signal
584d118 HEAD@{3}: rebase: fast-forward
ce8f2bf HEAD@{4}: rebase -i (start): checkout
eaf27f2 HEAD@{5}: rebase (continue) (finish): returning to refs/heads/stdhttp
eaf27f2 HEAD@{6}: rebase (continue) (pick): TEMP: count index 0
042ec6b HEAD@{7}: rebase (continue) (pick): f: tx revert
584d118 HEAD@{8}: rebase -i (start): checkout
d6664ce HEAD@{9}: commit: f: tx revert
669952e HEAD@{10}: commit: TEMP: count index 0
584d118 HEAD@{11}: commit: f: server: gold signal
ce8f2bf HEAD@{12}: commit: f: server: good job

I could see the line where I committed the reversion (I’m glad I take the extra half-second to give meaningful names to my fixups):

d6664ce HEAD@{9}: commit: f: tx revert

So then I did:

$ git co 669952e -- ./src/bot/telegram/telethonx.py

I got this from Joshua Wehner’s blog post: How to undo (almost) anything with Git in the section Redo after undo “local”.

Node

Node.js commands

Packages

`ncu` - npm-check-updates dependencies to the latest versions

$ ncu
Checking site/package.json
[====================] 2/2 100%
 express      ^4.9.0  →  ^4.17.1
 nodemon      ^2.0.3  →  ^2.0.4
Run ncu -u to upgrade package.json

$ ncu -u
Upgrading site/package.json
[====================] 2/2 100%
 express      ^4.9.0  →  ^4.17.1
 nodemon      ^2.0.3  →  ^2.0.4
Run npm install to install new versions.

`yarn` - package manager

How to update package.json after yarn updates:

$ yarn upgrade --latest
$ npm install

Unix

Simple commands that I don’t use often enough to remember them

Listeners

`netstat` - Print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships

$ netstat -tunlp
Proto  Local         Foreign    State   PID/Program name
tcp    0.0.0.0:80    0.0.0.0:*  LISTEN  8731/nginx: master
tcp    0.0.0.0:21    0.0.0.0:*  LISTEN  5752/sshd
tcp    0.0.0.0:443   0.0.0.0:*  LISTEN  8731/nginx: master
tcp6   :::80         :::*       LISTEN  8731/nginx: master
tcp6   :::21         :::*       LISTEN  5752/sshd
tcp6   :::443        :::*       LISTEN  8731/nginx: master

$ netstat -tulp
Proto  Local Address Foreign    State   PID/Program name
tcp    0.0.0.0:http  0.0.0.0:*  LISTEN  8731/nginx: master
tcp    0.0.0.0:ssh   0.0.0.0:*  LISTEN  5752/sshd
tcp    0.0.0.0:https 0.0.0.0:*  LISTEN  8731/nginx: master
tcp6   [::]:http     [::]:*     LISTEN  8731/nginx: master
tcp6   [::]:ssh      [::]:*     LISTEN  5752/sshd
tcp6   [::]:https    [::]:*     LISTEN  8731/nginx: master

`ss` - another utility to investigate sockets

$ ss -atpu
Netid State  Local Address:Port  Peer Address:Port
tcp   LISTEN       0.0.0.0:http       0.0.0.0:*      (("nginx",pid=26743,fd=15),("nginx",pid=26626,fd=15))
tcp   ESTAB    237.140.142:ssh  112.85.42.188:31809  (("sshd",pid=4159,fd=3),("sshd",pid=4158,fd=3))
tcp   ESTAB    237.140.142:ssh   75.39.85.160:41431  (("sshd",pid=4133,fd=3),("sshd",pid=4127,fd=3))
tcp   LISTEN          [::]:http          [::]:*      (("nginx",pid=26743,fd=16),("nginx",pid=26626,fd=16))
tcp   LISTEN          [::]:ssh           [::]:*      (("sshd",pid=622,fd=4))

`file` - determine file type

$ file ~/Pictures/the-national-plan.jpg
JPEG image data, JFIF standard 1.01, resolution (DPI),
density 72x72, segment length 16, comment: "Created with GIMP",
progressive, precision 8, 994x797, frames 3

IP

Get your outside IP number

$ wget http://ipecho.net/plain -O - -q ; echo
75.39.85.160

$ curl ipecho.net/plain; echo
75.39.85.160

$ curl ifconfig.me
75.39.85.160

$ curl icanhazip.com
2600:1700:c010:c40::44

$ nslookup varan
Server:         192.168.1.254
Address:        192.168.1.254#53

Name:   varan.attlocal.net
Address: 192.168.1.138
Name:   varan.attlocal.net
Address: 2600:1700:c010:c40:5e76:d88f:16d3:d8a4
Name:   varan.attlocal.net
Address: 2600:1700:c010:c40:a151:413a:de1e:f6a8
Name:   varan.attlocal.net
Address: 2600:1700:c010:c40::44
Name:   varan.attlocal.net
Address: 2600:1700:c010:c40:d943:2bf6:2800:4ddf
Name:   varan.attlocal.net
Address: fe80::167c:2090:9293:38c7

$ host varan
varan.attlocal.net has address 192.168.1.138
varan.attlocal.net has IPv6 address 2600:1700:c010:c40:a151:413a:de1e:f6a8
varan.attlocal.net has IPv6 address 2600:1700:c010:c40::44
varan.attlocal.net has IPv6 address 2600:1700:c010:c40:d943:2bf6:2800:4ddf
varan.attlocal.net has IPv6 address fe80::167c:2090:9293:c783
varan.attlocal.net has IPv6 address 2600:1700:c010:c40:5e76:d88f:16d3:d8a4

Linode Shell

Lish

$ ssh -t stav@lish-dallas.linode.com COWBOY
(exit to the Lish prompt by pressing ctrl+a then d)

Hardening

`last` - show a listing of last logged in users

$ last
stav     pts/0        75.39.85.160     Wed May 20 11:58   still logged in
stav     pts/2        75.39.85.160     Wed Mar  4 23:07   still logged in
stav     pts/1        75.39.85.160     Tue May 19 21:13 - 22:49  (01:36)
stav     pts/0        75.39.85.160     Tue May 19 19:29 - 22:49  (03:20)
stav     pts/0        75.39.85.160     Tue May 19 19:11 - 19:29  (00:17)

$ sudo lastb
change   ssh:notty    125.142.63.88    Sun Mar  1 00:00 - 00:00  (00:00)
root     ssh:notty    218.92.0.189     Sun Mar  1 00:00 - 00:00  (00:00)
rstudio1 ssh:notty    92.185.167.201   Sun Mar  1 00:00 - 00:00  (00:00)

`fail2ban` - read password failure reports and ban the corresponding IP addresses using firewall rules

$ cat /etc/fail2ban/jail.local
[sshd]
enabled  = true
port     = ssh
filter   = sshd
logpath  = /var/log/auth.log

$ sudo fail2ban-client status
Status
|- Number of jail:      1
`- Jail list:   sshd

$ sudo fail2ban-client status sshd
Status for the jail: sshd
|- Filter
|  |- Currently failed: 0
|  |- Total failed:     0
|  `- File list:        /var/log/auth.log
`- Actions
   |- Currently banned: 0
   |- Total banned:     0
   `- Banned IP list:

$ # sudo fail2ban-client reload sshd