Mail Basics — about MX records, A records, TXT records etc

CF. MainEnable Setup
Prerequisites >>
- install software on a Master Server
- Need A record of mail.Master Server
- Need MX record of mail.Master Server
- IIS needs to route traffic to the Master Server (for web console client)

• How to check ports running (used ports)
  netstat -ab
• Cp command
  copy DIRECTORY/filename DIRECTORY/tofilename
• View file (=cat)
  type <filename>
• Set environment variable (export $XXX)
  for /f %i in (<command>, output) do setx RELEASE_VERSION=%i /M
• 2 commands at once
  - IF you want to run it tgt (without sequence)
  : <command> & <command>
  - IF you want to run it with sequence (Dependency)
  : <command> && <command>
• How to redirect/configure IP tables
  <OPEN FIREWALL>
  : netsh advfirewall firewall add rule name=”HTTPS port” dir=in action=allow protocol=TCP localport=443
<REDIRECT TRAFFIC>
: netsh interface portproxy add v4tov4 listenport=443 connectport=8080 connectaddress=127.0.0.1

• In resource (EC2), you should provide securitygroupID, instead of actual securitygroup name → or will throw parameter group error
• If you launch AMI with Windows, the administrator password will be the same + also you will not be able to retrieve a new windows password
• AWS::CloudFormation::WaitCondition is to WAIT until the configuration stpes are done — before announcing the EC2 creation complete !
  Must use together with WaitConditionHandler
• If you use custom AMI image, User data will not probably be execued, since it’s already started
• Every command in the “init:config” section, will wait for 60 seconds to reboot if not specified “waitAfterCompletion: 0”

Standard process
git status
git add .
git commit -m “new change”
git push [repository name]

How to push to branch
git status
lets you check which branch you’re on
git branch OR git branch --list
git branch june
git checkout june

How to pull ONLY a branch repo
git clone -b june <repo url>

If there is no “REMOTE” repository but have “local” repository
will get error that there is no upstream branch
git push --set-upstream origin[repositoryname] june

How to check origin (=remote branch)
git remote -v
git remote set-url origin new.git.url/here

When your instance failes to create
— Because they failed to create specific resources (security group, route53)
— Because the success health check signal didn’t come through for a certain time → This doesn’t give you much info about error
(Mostly because of Metadata(cfn-init) or UserData)

Then How should we Troubleshoot?
* Turn Off the “roll back function”
- So we can go into the instance to troubleshoot
→ ‘Stack Creation Option’ : Rollback — disable (When launching template)

Then SSH into instance and Check — Metadata, Userdata, etc
* /var/log/cfn-init.log
* Check User Data Script : cat /var/lib/cloud/instance/scripts/part-001