Your Inner Sysadmin - MidwestPHP 2015

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One thing that most programmers do not take the time to understand is the servers that their application lives on. Most know a smattering of Apache configs, PHP configs, and basic information about the OS. This talk will deal with looking at tools that can help you quickly set up a server and how it can help you be a better developer. We'll look at tools like Puppet for server management, OSSEC for log management, different command line tools, and Nagios/Monit for system monitoring.

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Your Inner Sysadmin - MidwestPHP 2015

  1. 1. Your Inner Sysadmin Chris Tankersley @dragonmantank MidwestPHP 2015 MidwestPHP 2015 1
  2. 2. Who Am I • PHP Programmer for over 10 years • Sysadmin/DevOps for around 8 years • Using Linux for more than 15 years • https://github.com/dragon mantank MidwestPHP 2015 2
  3. 3. Here Be Dragons MidwestPHP 2015 3
  4. 4. Traditional Lamp Stack MidwestPHP 2015 4
  5. 5. Our Players MidwestPHP 2015 5
  6. 6. And of course… MidwestPHP 2015 6
  7. 7. The Server • /bin - Essential user executable files • /boot - Stuff that makes the OS boot up! • /dev - Special device stuff you probably won't touch • /etc - Configuration files • /home - User home directories • /sbin - System binaries • /usr - Multi-user apps and utilities • /var - Data usually lives here MidwestPHP 2015 7
  8. 8. Installing Software • Compile software from scratch • Use the package manager (yum/apt) MidwestPHP 2015 8
  9. 9. Learn to love the Command Line MidwestPHP 2015 9
  10. 10. Learn a CLI text editor • vi/vim • emacs • nano MidwestPHP 2015 10
  11. 11. Authentication and Authorization MidwestPHP 2015 11
  12. 12. sudo You can give admin access to users (or groups of users) without giving them root. MidwestPHP 2015 12 # Add sudo access to a single user to run as root dragonmantank ALL=(ALL) ALL # Add sudo access to a full group %admin ALL=(ALL) ALL You can even restrict what commands the users can run # Restrict web developers to only restart Apache and MySQL %webdevs 192.168.1.0/255.255.225.0=(root) NOPASSWD:/usr/sbin/service apache2 restart, /usr/sbin/service mysql restart
  13. 13. Jailing Users Keeps people from getting to things they shouldn't. Protects the users from themselves. MidwestPHP 2015 13
  14. 14. Jailed Shells Gives users a full shell but not the entire file system. You can pick and choose what programs the user can have access too. Jailkit makes this incredibly easy to set up. MidwestPHP 2015 14
  15. 15. Jailed SFTP Locks the user to a specific base path, but doesn’t give them a shell, much like FTP. You get the security of SSH though! It does require a system user however. MidwestPHP 2015 15
  16. 16. Jailing SFTP # In /etc/ssh/sshd_config Subsystem ftp sftp-internal # At the bottom of the file Match User jailedsftp ChrootDirectory /some/path AllowTCPForwarding no X11Forwarding no ForceCommand internal-sftp MidwestPHP 2015 16
  17. 17. Docker MidwestPHP 2015 17 If you do it the non-Docker way
  18. 18. Scripting Languages MidwestPHP 2015 18
  19. 19. Bash Most servers use bash as the default shell. Most shells understand bash's syntax. If you find yourself running the same commands over and over, throw it in a bash script. MidwestPHP 2015 19
  20. 20. Python Ships with most distros. Great for when you need more power than what bash has. MidwestPHP 2015 20
  21. 21. PHP! Leverage your PHP skills to write shell scripts. • Symfony Console Component • Aura CLI MidwestPHP 2015 21
  22. 22. Locking Down your Code MidwestPHP 2015 22
  23. 23. Running Apache as a different user MPM-ITK MidwestPHP 2015 23 MOD_RUID2 <IfModule mpm_itk_module> AssignUserId [user] [user] </IfModule> RMode config RUidGid myuser mygroup RDocumentChRoot /var/www/vhosts/domain.com/ www/public
  24. 24. PHP-FPM user = myuser group = mygroup chroot = /path/to/my/chroot MidwestPHP 2015 24
  25. 25. Logs MidwestPHP 2015 25
  26. 26. Logrotate Rotates logs out for organization (or other purposes) MidwestPHP 2015 26 weekly rotate 4 create include /etc/logrotate.d /var/log/wtmp { monthly minsize 1M create 0664 root utmp rotate 1 }
  27. 27. Logwatch Script that runs every so often and scans a bunch of logs so you get a pretty e-mail with a summary of events MidwestPHP 2015 27 --------------------- httpd Begin ------------------------ 0.17 MB transferred in 792 responses (1xx 0, 2xx 786, 3xx 0, 4xx 6, 5xx 0) 199 Content pages (0.09 MB), 593 Other (0.09 MB) Requests with error response codes 400 Bad Request /w00tw00t.at.ISC.SANS.DFind:): 1 Time(s) 404 Not Found /MyAdmin/scripts/setup.php: 1 Time(s) /phpmyadmin/scripts/setup.php: 1 Time(s) /w00tw00t.at.blackhats.romanian.anti-sec:): 1 Time(s) /webdav/: 2 Time(s) ---------------------- httpd End -------------------------
  28. 28. OSSEC Actually a Host Intrusion Detection system, but it does this by watching logs. Will alert you immediately to problems, and even shut down the attacks. MidwestPHP 2015 28 OSSEC HIDS Notification. 2012 Oct 24 11:38:10 Received From: maple->/var/log/auth.log Rule: 5712 fired (level 10) -> "SSHD brute force trying to get access to the system." Portion of the log(s): Oct 24 11:38:09 maple sshd[1062]: Failed password for invalid user alias from 199.167.138.44 port 59988 ssh2 Oct 24 11:38:07 maple sshd[1062]: Invalid user alias from 199.167.138.44 Oct 24 11:38:06 maple sshd[1059]: Failed password for invalid user recruit from 199.167.138.44 port 59884 ssh2
  29. 29. Preventing Intruders MidwestPHP 2015 29
  30. 30. hosts.deny and hosts.allow Set of files to allow or deny access to the machine or certain apps/ports on the machine MidwestPHP 2015 30
  31. 31. IPTables A firewall that is generally available on Linux machines that can be configured many different ways to allow or block or mangle traffic MidwestPHP 2015 31
  32. 32. OSSEC IDS that was logs and will use hosts.deny and iptables to block stuff automatically for you! MidwestPHP 2015 32
  33. 33. Configuration Management MidwestPHP 2015 33
  34. 34. What is Configuration Management? Process by which you figure out what goes on your servers, how you want them set up, and keeping track of that information. Files are usually stored in source control on one server and pushed to clients. MidwestPHP 2015 34
  35. 35. Why do you need it? • Ever needed to keep track of when files get changed? • Ever needed to roll back a change? • Ever needed to push the same change to a bunch of servers • Ever needed to set up a server exactly the same way as another server? MidwestPHP 2015 35
  36. 36. General CM Workflow MidwestPHP 2015 36 Write a Manifest file Client checks and compiles the manifests Client makes changes based on manifests
  37. 37. Ansible • https://serversforhackers.com/getting-started- with-ansible/ MidwestPHP 2015 37
  38. 38. Puppet • http://www.erikaheidi.com/page/vagrant MidwestPHP 2015 38
  39. 39. Server Monitoring MidwestPHP 2015 39
  40. 40. Quick Poll • Who here knows that their server is up right now? • Are all of the required services running? • Are there enough resources currently available? MidwestPHP 2015 40
  41. 41. Service Monitoring with Monit MidwestPHP 2015 41
  42. 42. Host Monitoring with Icinga MidwestPHP 2015 42
  43. 43. Software Tools MidwestPHP 2015 43
  44. 44. tmux/screen Command line multiplexer MidwestPHP 2015 44
  45. 45. tail Look at the newest entries in a log, or even watch log files as they are generated MidwestPHP 2015 45
  46. 46. curl Command line program for transferring data via a URL MidwestPHP 2015 46
  47. 47. iftop Displays a breakdown of bandwidth usage by host MidwestPHP 2015 47
  48. 48. htop Slightly better interface for checking memory and CPU usage MidwestPHP 2015 48
  49. 49. tcpdump Allows you to view and record data transmitted over the network. Couple this with wireshark and you can inspect the packets! MidwestPHP 2015 49
  50. 50. Servers for Hackers Chris Fidao @fideloper http://serversforhackers. com MidwestPHP 2015 50
  51. 51. Questions? MidwestPHP 2015 51
  52. 52. Thank You! http://ctankersley.com chris@ctankersley.com @dragonmantank https://joind.in/13069 MidwestPHP 2015 52

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