Today I learnt

Today I learned about keychain and how to use it to manage ssh and gpg agents. Keychain create one ssh-agent per system, unlike ssh-agent that creates one agent per login session (if placed in zprofile) and require multiple ssh-add for keys. In addition to that ssh-agent is not compatible with cron jobs or shell scripts because they do not inherit the SSH_AUTH_SOCK variable from the environnement. # run a ssh agent and add the id_rsa key (using keychain) eval `keychain --eval --agents ssh id_rsa` Option Use –agents specify agents to run (gpg or ssh) –clear clear the cached keys for every new login -k [all|mine] kill all the agents, or only agents started by keychain –dir specify the dir where the SSH_AUTH_SOCK will be cached

Today I learned about git tags, and how to use them to control job triggering in gitlab ci. Git tags are ref’s that point to specific points in Git history. There are two types: Lightweight which act as bookmarks for specific commits (can be thought of as private) and Annotated which stores extra meta data like tagger’s name and email address. git tag <tagname> #lightweight git tag -a <tagname> -m <tag_message> #annotated To trigger jobs according to tags we either use only:/except: or job(or workflow) rules....

Today I learned how to get information about databases and tables in mysql. show databases; use <database-name> show tables; describe <table-name>;

AWS restricts traffic on port 25 of all EC2 instances by default, you should open a request to remove the restriction. More details here

Today I learned how to prevent tmux from starting a login shell set-option -g default-command zsh Here

Today I learned that rofi has two configuration syntaxes, the Xressource-like and the json-like (rasi).

Today I learned about openbsd, a unix-like OS, focusing on the security. I also learned about the SMTP protocol, and Opensmtpd the default SMTP server for openbsd. I also studied a vulnerability present in opensmtpd and exploited it. Opensmtpd CVE-2020-7247 The exploit