17. Networking

This chapter applies Bash to network checks, downloads, secure file transfer, remote execution, and remote automation.

• Diagnostics: Use commands such as ping and curl to inspect connectivity.

• Retrieval: Download data and check responses before processing them.

• Transfer: Move files between systems with scp and rsync.

• Remote execution: Run commands over SSH while preserving safety and quoting.

• Automation: Coordinate remote checks and deployments across hosts.

Chapter Video

Linux Crash Course: Connecting to Linux Servers via SSH (15:54) by Learn Linux TV

Hosted on YouTube; property of its original creator, embedded here for educational reference only.

Learning Objectives

By the end of this chapter, you will be able to:

1. Use ping, curl, and wget for network inspection and retrieval.

2. Transfer files securely with scp and rsync.

3. Run remote commands with ssh safely.

4. Automate network and remote-system checks.

Chapter Flow

1. Network Commands: Ping, Curl, and Wget

2. Secure File Transfer: SCP and Rsync

3. Remote Execution with SSH

4. Network Automation

Glossary

#	Term	Explanation
1	Network diagnostic	A command or technique used to check network behavior.
2	ping	A command that tests whether a host responds to ICMP echo requests.
3	curl	A command-line tool for making URL-based requests.
4	wget	A command-line tool commonly used for downloading files.
5	HTTP status code	A numeric response code such as 200, 404, or 500.
6	Timeout	A maximum waiting period before a network operation fails.
7	Retry	A repeated attempt after a transient failure.
8	SSH	A secure protocol for remote login and command execution.
9	SSH key	A cryptographic credential used for SSH authentication.
10	Known hosts	The SSH record of host keys previously seen by the client.
11	Remote command	A command executed on another system through SSH.
12	Quoting boundary	The point where local shell expansion and remote shell expansion must be separated.
13	scp	A command for copying files over SSH.
14	rsync	A synchronization tool that copies only changed data when possible.
15	Trailing slash	A slash that changes whether rsync copies a directory itself or its contents.
16	Deployment	The process of copying and activating files or configuration on a target system.
17	Remote host	A system accessed over a network.
18	Connectivity check	A quick test that a network target is reachable.
19	API request	A structured network request to a service endpoint.
20	Monitoring script	Automation that checks remote systems and reports status.