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00:38, 27 August 2024 Ardika Sulistija talk contribs created page Linux Permissions (Created page with "<div style='text-align: center;'>Users, Groups, and Ownership</div> ====Linux Permissions==== ---- =====What are User and Group Permissions?===== * Linux was designed to allow more than one user to have access to the system at the same time. In order for this multiuser design to work properly, there needs to be a method to protect users from each other. * Permissions are the "<...")
00:38, 27 August 2024 Ardika Sulistija talk contribs created page Linux Directory Structure (Created page with "https://www.telecomworld101.com/Linux14-DirectoryStructure.html")
00:38, 27 August 2024 Ardika Sulistija talk contribs created page Less (Created page with "====What is the difference between Less and More?==== ---- more is the oldest, less is an improvement and most is an improvement on that. Short comparison: more: forward navigation and limited backward navigation. less: both forward and backward navigation and also has search options. You can go to the beginning and the end of a file instantly. Plus you can switch to an editor (like open the file in vi or vim). It is noticeably quicker than editor for when the file is...")
00:37, 27 August 2024 Ardika Sulistija talk contribs created page Last (Created page with "https://www.thegeekstuff.com/2009/03/4-ways-to-identify-who-is-logged-in-on-your-linux-system/ last command will give login history for a specific username. If we don’t give any argument for this command, it will list login history for all users. By default this information will read from /var/log/wtmp file. The output of this command contains the following columns: * User name * Tty device number * Login date and time * Logout time * Total working time $ las...")
00:36, 27 August 2024 Ardika Sulistija talk contribs created page LVM (Created page with "ADD NOTES: https://xan.manning.io/2017/05/29/best-practice-for-mounting-an-lvm-logical-volume-with-etc-fstab.html (LVM snapshot can cause issues if you mount using UUID!!!) ====LVM Architecture and Terminology==== ---- lvm - Logical Volume Manager/management. * It is a storage device management technology that gives users the power to pool and abstract the physical layout of component storage devices for easier (ha) and flexible administration. * It utilizes...")
00:36, 27 August 2024 Ardika Sulistija talk contribs created page LAMP Stack (Created page with "==== How to install a LAMP stack: ==== ---- For Red Hat Enterprise Linux version 8: RHEL8 includes PHP 7.2 so the standard PHP is fine and Software Collections isn't needed: dnf install httpd php php-mysqlnd php-gd php-xml mariadb-server mariadb php-mbstring php-json Ubuntu 16.04.2 LTS (Xenial) and Debian Stretch include PHP 7.0, and renamed many packages from "php5" to plain "php". In addition, some PHP modules are now in separate packages (xml, mbstring): apt-get...")
00:36, 27 August 2024 Ardika Sulistija talk contribs created page Kernel (Created page with "The kernel is the heart of the Linux operating system. It's responsible for scheduling running programs, file management, and security. If you have a device driver, it runs in the kernel. Networking is implemented in the kernel. This is what we mean as kernel space. The kernel's job is also to support user programs, which run in user space like shell, web browser, or similar programs. User space programs interact with a kernel through special devices or s...")
00:36, 27 August 2024 Ardika Sulistija talk contribs created page KMS (Created page with "If you suspect a KMS issue, check cloudtrail for the following events to see if there are any kms permission errors: * GenerateDataKeyWithoutPlaintext * ReEncrypt * Decrypt")
00:30, 27 August 2024 Ardika Sulistija talk contribs created page Jq (Created page with "https://earthly.dev/blog/jq-select/")
00:30, 27 August 2024 Ardika Sulistija talk contribs created page Journald (Created page with "Enable persistent logging: https://www.golinuxcloud.com/enable-persistent-logging-in-systemd-journald/ https://access.redhat.com/solutions/696893")
00:30, 27 August 2024 Ardika Sulistija talk contribs created page Journalctl (Created page with "journalctl --no-pager --catalog --boot")
00:29, 27 August 2024 Ardika Sulistija talk contribs created page Java (Created page with "To replicate customer's java code/issue, use AWS Cloud9!!! * Get started with the AWS SDK for Java 2.x (Quick start) https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html * Install Java and a build tool https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/setup.html#setup-envtools * Amazon Corretto 8 Installation Instructions for Amazon Linux 2 https://docs.aws.amazon.com/corretto/latest/corretto-8-ug/amazon-linux-install.html...")
00:29, 27 August 2024 Ardika Sulistija talk contribs created page Iptables (Created page with " iptables/ip6tables -- administration tool for IPv4/IPv6 packet filtering and NAT AWS Specific: In normal circumstances we do not use iptables to block traffic in AWS. We rely on the security groups and Network ACLs for this purpose. iptables on an instance is normally used for NAT instances or instance-based VPN, i.e. OpenSwan, OpenVPN, StrongSwan or Sophos UTM. You can sometimes use iptables to block traffic on an instance. For example, u...")
00:29, 27 August 2024 Ardika Sulistija talk contribs created page Iperf (Created page with "https://www.slashroot.in/iperf-how-test-network-speedperformancebandwidth https://aws.amazon.com/premiumsupport/knowledge-center/network-throughput-benchmark-linux-ec2/ ====How to test network bandwidth==== To test your uplink speed, you can you utility such as the iperf3 utility as follows: 1) on the listener/destination: iperf3 -s -p 1500 2) On source run: iperf3 -i 10 -c Vanilla_linux_server_ip -p 1500 -t 60 > iperf60.log iperf3 -i 10 -c Vanilla_linux_server...")
00:28, 27 August 2024 Ardika Sulistija talk contribs created page Iostat (Created page with " iostat - Report Central Processing Unit (CPU) statistics and input/output statistics for devices and partitions. $ iostat Linux 4.14.158-129.185.amzn2.x86_64 (ip-172-31-33-239.ec2.internal) 02/24/2020 _x86_64_ (2 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 0.15 0.00 0.11 0.01 0.04 99.70 Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn nvme0n1 0.86 2.81 5.86...")
00:28, 27 August 2024 Ardika Sulistija talk contribs created page Install and Enable ENA drivers for Nitro (Created page with " How do I install and enable the latest ENA driver for Enhanced Network Support on an Amazon EC2 instance running Red Hat 6/7? https://aws.amazon.com/premiumsupport/knowledge-center/install-ena-driver-rhel-ec2/ ====How to launch RHEL 6 on Nitro-instance==== ---- Yes, it is possible to run RHEL 6 on Nitro-isntances (M5, C5, T3). I have tested this out using AMI: ami-0351faf7328fdb373 (RHEL 6.10 - HVM - Red Hat Provided, ENA: no). 1) First make sure NVMe driver is...")
00:27, 27 August 2024 Ardika Sulistija talk contribs created page Inodes (Created page with " inodes are associated with each linux file and the system can run out of inodes when multiple smaller files are created. Inodes are references to the physical location of files on the file system. Each individual file uses one inode. Study and add notes: https://helpdeskgeek.com/linux-tips/what-are-inodes-in-linux-and-how-are-they-used/ https://unix.stackexchange.com/questions/117093/find-where-inodes-are-being-used Running out of inodes generally means you've g...")
00:25, 27 August 2024 Ardika Sulistija talk contribs created page Ifconfig (Created page with " ifconfig - *technically obsolete (use ip addr instead)* Show interface info, IP address, mac address, etc. $ sudo ifconfig eth0 eth0 Link encap:Ethernet HWaddr 00:17:42:1f:18:be inet addr:10.1.1.7 Bcast:10.1.1.255 Mask:255.255.255.0 inet6 addr: fe80::217:42ff:fe1f:18be/64 Scope:Link UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:1 errors:0 dropped:0 overruns:0 frame:0 TX packets:11 err...")
00:24, 27 August 2024 Ardika Sulistija talk contribs created page IPv4 (Created page with "====How to find your own IP==== ---- $ curl wtfismyip.com/json { "YourFuckingIPAddress": "52.94.133.131", "YourFuckingLocation": "Richmond, VA, United States", "YourFuckingHostname": "52.94.133.131", "YourFuckingISP": "X Office", "YourFuckingTorExit": false, "YourFuckingCountryCode": "US" } $ curl ifconfig.me 72.21.196.67")
00:21, 27 August 2024 Ardika Sulistija talk contribs created page IOwait (Created page with "Good article: https://haydenjames.io/what-is-iowait-and-linux-performance/ Troubleshooting high IOwait in Linux: https://madflojo.medium.com/troubleshooting-high-i-o-wait-in-linux-358080d57b69")
00:21, 27 August 2024 Ardika Sulistija talk contribs created page Hyper-V (Created page with "====Adding your ISO file from the Library server to the HyperV server as a physical library object==== ---- # Log in to the HyperV server # Click on the Virtual Machine Manager Console shortcut on the Desktop. # Enter the Server name and click Connect # On the left hand navigation pane, select Library in the bottom section. # Click Import Physical Resource in the top banner # Click Add resource # Go to Network, wait a co...")
00:21, 27 August 2024 Ardika Sulistija talk contribs created page History (Created page with "history - This commands stores the executed commands ran by a user. Typically, these commands are store in the user's home directory: /home/<user>/.bash_history For root user, it will be in: /root/.bash_history You can search where the .bash_history file is by running: $ echo $HISTFILE /home/ec2-user/.bash_history # Run as root $ echo $HISTFILE /root/.bash_history ====How to Increase the History Size==== ---- First, check curren...")
00:20, 27 August 2024 Ardika Sulistija talk contribs created page Hard Links / Soft Links (Created page with "There are two types of links: * symbolic links (also known as “soft links” or “symlinks”): Refer to a symbolic path indicating the abstract location of another file. * hard links: Refer to the specific location of physical data. ====Soft Links==== ---- How to: Linux / UNIX create soft link with ln command https://www.cyberciti.biz/faq/creating-soft-link-or-symbolic-link/ =====How to c...")
00:19, 27 August 2024 Ardika Sulistija talk contribs created page Grep (Created page with "grep - Pretty much a search function. Prints lines matching a pattern. ----- Examples: cat [file] | grep "word" # Prints any line with "word" grep -i # Ignore case senisitivity *i is for INSENSITIVE* grep -irl [word] [dir] # Ignore case distinctions, Read all files under each directory, recursively, Suppress normal output; grep [word] [in file/dir] # Searches up "word" in that file or dir g...")
00:19, 27 August 2024 Ardika Sulistija talk contribs created page Git (Created page with "git - The stupid content tracker. Git is a stupid content tracker because it has no idea what's inside those blobs, and it doesn't try to store fine grained information like "lines 345-350 added, lines 502-508 removed" or anything like that. https://github.com/git-guides ====How to clone github repository to your local terminal==== ---- $ git clone https://github.com/ardikas/shell-scripts ====How to set up your terminal with remote access to your Github repo==...")
00:19, 27 August 2024 Ardika Sulistija talk contribs created page Gdisk (Created page with "Under construction")
00:18, 27 August 2024 Ardika Sulistija talk contribs created page Gcc (Created page with "====How to install gcc on RHEL6==== ---- Tested on RHEL6.9: mkdir /mnt/rhel6dvd mount /dev/sr0 /mnt/rhel6dvd # ensure the DVD Iso is connected to the VM vi /etc/yum.repos.d/dvd.repo [dvd-Server] mediaid=1409145026.642170 name=RHEL 6 Server DVD baseurl=file:///mnt/rhel6dvd/Server gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release enabled=1 gpgcheck=1 yum -y install gcc ====How to install gcc manually on RHEL6.10==== ---- Note: This works...")
00:18, 27 August 2024 Ardika Sulistija talk contribs created page GRUB (Created page with " GRUB -- Grand Unified Bootloader; executes the Kernel. * GRUB goes through two stages. * After the two stages, the kernel and initrd is loaded into memory. * Config files: ** GRUB 1 (old vers) /etc/grub.conf -> /boot/grub/grub.conf ** GRUB 2 (New Grub) /etc/grub2.cfg -> /boot/grub2/grub.cfg *** GRUB 2 reads its configuration from the /boot/grub2/grub.cfg file on traditional BIOS-based machines and from the /boot...")
00:17, 27 August 2024 Ardika Sulistija talk contribs created page Fstab (Created page with "ADD NOTES: https://xan.manning.io/2017/05/29/best-practice-for-mounting-an-lvm-logical-volume-with-etc-fstab.html /etc/fstab - static information about the filesystems (aka file system table) The file fstab contains descriptive information about the filesystems the system can mount. fstab is only read by programs, and not written; It is the duty of the system administrator to properly create and maintain this file. The order of records in fstab is...")
00:17, 27 August 2024 Ardika Sulistija talk contribs created page Fsck (Created page with "UNDER CONSTRUCTION https://www.tecmint.com/fsck-repair-file-system-errors-in-linux/ BE SURE TO UMOUNT THE FILESYSTEM BEFORE RUNNING FSCK!!!! e2fsck - ext2 I believe. But fsck will detect it If the root filesystem is getting mounted as "Read-only" (ro) then you will need to detach it, attach it to another instance as a secondary volume, and run fsck.")
00:16, 27 August 2024 Ardika Sulistija talk contribs created page FreeBSD (Created page with "Network config file location: * /etc/rc.conf * Default EC2 instance: # cat /etc/rc.conf ec2_configinit_enable=YES ec2_fetchkey_enable=YES ec2_ephemeralswap_enable=YES ec2_loghostkey_enable=YES firstboot_freebsd_update_enable=YES firstboot_pkgs_enable=YES growfs_enable="YES" ifconfig_DEFAULT="SYNCDHCP" sshd_enable="YES" firstboot_pkgs_list="awscli" https://www.serverlab.ca/tutorials/unix/how-to-set-static-ip-and-dhcp-in-freebsd/ ---- LSBLK equivalent in Fr...")
00:16, 27 August 2024 Ardika Sulistija talk contribs created page Free (Created page with "free - Display amount of free and used memory in the system, as well as the buffer used by the kernel, and the used physical and swap memory. It displays the total amount of free and used physical and swap memory in the system, as well as the buffers and caches used by the kernel. The information is gathered by parsing /proc/meminfo. * total - Total installed memory (MemTotal and SwapTotal in /proc/meminfo) * used - Used memory (calculat...")
00:16, 27 August 2024 Ardika Sulistija talk contribs created page Firewalls (Created page with "There are different types of firewalls. Let's review: Types of firewalls: * iptables - Till RHEL6/CentOS6, and similar. * netfilter - kernel module * ufw - Ubuntu * pf - BSD * firewalld - RHEL7+")
00:15, 27 August 2024 Ardika Sulistija talk contribs created page Firewalld (Created page with "https://www.tecmint.com/start-stop-disable-enable-firewalld-iptables-firewall/ Good article: https://www.linode.com/docs/guides/introduction-to-firewalld-on-centos/ firewalld - A wrapper for iptables to allow easier management of iptables rules. Is not an iptables replacement. It's a firewall service daemon that provides a dynamic customizable host-based firewall with a D-Bus interface. It enables creating, changing, and deleting the rules without...")
00:15, 27 August 2024 Ardika Sulistija talk contribs created page Find (Created page with "find - Search for files in a directory hierarchy. ---- Examples: find /dir -name "filename" # Searches up the "dir" directory with "filename" find /dir -iname "filename" # ^^^ does the same but insensitive. find /dir -emtpy # Searches up all the empty files in "dir" directory. Displays the 5 LARGEST files in the directory THAT YOU ARE IN. (hence the dot (.) find . -type f -exec ls -s {} \; | sprt -n -r | head -5 Displays the...")
00:15, 27 August 2024 Ardika Sulistija talk contribs created page Fdisk & Gdisk (Created page with "If you do not know whether the VM uses MBR or GPT partitions, log into the VM as root and enter one of the following commands. * **fdisk -l /dev/xvda** - For MBR partitions, the operating system will be shown in the Disklabel type field. # fdisk -l /dev/xvda Welcome to fdisk (util-linux 2.27.1). Changes will remain in memory only, until you decide to write them. Be careful before using the write command. Command (m for help): p Disk /dev/xvd...")
00:14, 27 August 2024 Ardika Sulistija talk contribs created page Fail2ban (Created page with "Fail2ban - a set of server and client programs to limit brute force authentication attempts. ====How to set up fail2ban for ssh:==== ---- 1) Install fail2ban 2) Create a new file by copying jail.conf to a new file called jail.local ‘cp jail.conf jail.local’ 3) Configure jail.local: Bantime; number of seconds that a host is banned. Findtime; the max amount of time to complete the login process. If they don’t do it, they will be banned...")
00:14, 27 August 2024 Ardika Sulistija talk contribs created page FIPS (Created page with "====How to check if FIPS is enabled==== ---- Check that FIPS mode is enabled: $ fips-mode-setup --check FIPS mode is enabled. ====Kernel Parameter for enabling FIPS==== ---- fips=1")
00:14, 27 August 2024 Ardika Sulistija talk contribs created page Excel (Created page with "====Sort a Table by IP Address==== ---- #. Create a new column to the left of the IP Address column. Let's call it the Sorted column #. Copy the IP addresses from the IP Address column to the new column (Sorted) #. In the Sorted column, use the "find and replace" feature to remove the first three octets so that you are left with the last octet only ##. For example, it the IP addresses are "10.240.5.4", then find "10.240.5." and replace...")
00:13, 27 August 2024 Ardika Sulistija talk contribs created page Ethtool (Created page with "ethtool - query or control network driver and hardware settings. Use this command to verify that your link is up (the Ethernet is physically connected to the network). https://www.poftut.com/linux-ethtool-tutorial-usage-examples/ ====Is it plugged in?==== ---- On a physical server, with physical cables connected to them, it would probably look like: $ sudo ethtool eth0 Settings for eth0: Supported ports: [ TP ] Supported link modes: 10baseT/Half 10bas...")
00:13, 27 August 2024 Ardika Sulistija talk contribs created page Ephemeral Port (Created page with " What is an ephemeral port? It is a port that is only used for short period. It is typically used by a client when it connects to a server. The range is usually 49152 through 65535 but does vary. The client end of a connection typically uses a high port number allocated for short term use. ---- Other definitions: [https://www.techopedia.com/definition/19157/ephemeral-port Techopedia:] In client-server processes that use Transmission Control Protoco...")
00:12, 27 August 2024 Ardika Sulistija talk contribs created page Environment Variables (Created page with "====How to set environment variables in Linux? (proxy examples)==== ---- Check current proxy configuration status (https_proxy/https_proxy)/ This variable will show if there is a proxy server configured on the system: # echo $http_proxy # echo $https_proxy Set up proxy without username and password # export http_proxy=http://SERVER:PORT/ # export https_proxy=http://SERVER:PORT/ # export no_proxy=localhost,127.0.0.1,169.254.169.254,.amazonaws.com...")
00:12, 27 August 2024 Ardika Sulistija talk contribs created page Entropy (Created page with "Reference: https://major.io/2007/07/01/check-available-entropy-in-linux/ Check available entropy in Linux Sometimes servers just have the weirdest SSL problems ever. In some of these situations, the entropy has been drained. Entropy is the measure of the random numbers available from /dev/urandom, and if you run out, you can’t make SSL connections. To check the status of your server’s entropy, just run the following: # cat /proc/sys/kernel/random/entropy_avail If i...")
00:12, 27 August 2024 Ardika Sulistija talk contribs created page ElastiCache (Created page with "====How to install Redis-cli==== ---- How to install Redis-cli on Amazon Linux 2: $ sudo yum -y install openssl-devel gcc $ wget http://download.redis.io/redis-stable.tar.gz $ tar xvzf redis-stable.tar.gz $ cd redis-stable $ make distclean $ make redis-cli BUILD_TLS=yes $ sudo install -m 755 src/redis-cli /usr/local/bin/ ==== Is there downtime when changing node type? (scaling up)==== ---- Reference: [1] Cluster mode disabled https://docs.aws.amazon...")
00:10, 27 August 2024 Ardika Sulistija talk contribs created page EFS (Created page with "EFS - Elastic Filesystem ====Other methods besides DD==== ---- * How can I copy data to and from Amazon EFS in parallel to maximize performance on my EC2 instance? https://aws.amazon.com/premiumsupport/knowledge-center/efs-copy-data-in-parallel/ DD is not parallel, so there are other methods to create files much quicker than DD. Below is a process on how you can do so: 1) Create ten thousand small files in your local storage on your instance. $ mkdir /t...")
00:10, 27 August 2024 Ardika Sulistija talk contribs created page ECS (Created page with "ECS - Amazon Elastic Container Service https://docs.aws.amazon.com/AmazonECS/latest/developerguide/Welcome.html Related Topics: Docker, Docker Troubleshooting and CLI, ECR Really good blog post about how ECS manages CPU and memory resources: https://aws.amazon.com/blogs/containers/how-amazon-ecs-manages-cpu-and-memory-resources/ ====ECS Components==== ---- =====Cluster==...")
00:10, 27 August 2024 Ardika Sulistija talk contribs created page ECR (Created page with "* Docker * Docker Troubleshooting and CLI ---- ECR - Amazon Elastic Container Registry * A fully managed private docker container registry service that makes it easy to store, pull, and push docker images securely. * ECR automatically encrypts images at rest using S3 server-side encryption and transfers your container images over HTTPS. * ECR uses AWS S3 service in the back-end to host images in a Hig...")
00:09, 27 August 2024 Ardika Sulistija talk contribs created page EC2 (Created page with "the default user name for the AMI that you used to launch your instance: * For Amazon Linux 2 or the Amazon Linux AMI, the user name is ec2-user. * For a CentOS AMI, the user name is centos. * For a Debian AMI, the user name is admin. * For a Fedora AMI, the user name is ec2-user or fedora. * For a RHEL AMI, the user name is ec2-user or root. * For a SUSE AMI, the user...")
00:09, 27 August 2024 Ardika Sulistija talk contribs created page EBS (Created page with " ====How to list and delete EBS Snapshots in Bulk==== ---- How to list all EBS snapshots: https://aws.amazon.com/premiumsupport/knowledge-center/ebs-volume-snapshot-ec2-instance/ How to delete EBS snapshots in bulk: * This deletes all EBS snapshots created before 2020-07-28: $ for i in $(aws ec2 describe-snapshots --owner-ids self --query 'Snapshots[?StartTime<=`2020-07-28`].SnapshotId' --output text); do aws ec2 delete-snapshot --snapshot-id $i; sleep 5; done; * An...")
14:49, 21 August 2024 Ardika Sulistija talk contribs created page Du (Created page with " du - estimate file space usage. Summarizes disk usage of each FILE, recursively for directories. The two commands (df & du) reports their figures from different sources, and changes to the filesystems are not always considered in the same way. The disk free command (abbreviated to "df") is the standard Linux/Unix command used to display available disk space for the file systems. The "df" command uses the statvfs() system call and asks the file system for the c...")