Network Clients

2 June 2015 - Linux Linux Basics Network SSH FTP

Overview

Web Clients

Links

Links is a Text Based (Non GUI) Web Broser.
Provided by the elinks package.
Full support for Frames and SSL.

Examples:

[mitesh@Matrix ~]$ links http://www.redhat.com
[mitesh@Matrix ~]$ links -dump http://www.redhat.com
[mitesh@Matrix ~]$ links -source http://www.redhat.com

Wget

The wget is a non-interactive network downloader.
Retrieves files via HTTP and FTP.

Options:

/-----------------------------------------------------------------------------------------------\
|												|
|	--continue (-c)	|	Continue Partially Downloaded File				|
|												|
|	--tries=number	|	Retry the specified number of times to download the files	|
|	--wait=seconds	|	Wait the specified number of seconds between the retrievals	|
|												|
|	--recursive	|	Turn on recursive retrieving					|
|	--level=depth	|	Specify recursion maximum depth level				|
|			|	(The default maximum depth is 5)				|
|	--convert-links	|	After download is complete convert all links,			|
|			|	To make them suitable for local viewing				|
|												|
\-----------------------------------------------------------------------------------------------/

Examples:

[mitesh@Matrix ~]$ wget http://www.redhat.com/training/index.html

[mitesh@Matrix ~]$ wget -c ftp://ftp.site.com/selinux.tar.gz

[mitesh@Matrix ~]$ wget --tries=50 --wait=30 ftp://ftp.site.com/files

[mitesh@Matrix ~]$ wget --recursive --level=1 --convert-links http://www.site.com

Google Chrome/Firefox

Tabbed Browsing
Popup Blocking
Cookie Manageent
Themes and Extensions
Multi-Engine Search Bar
Supports For Many Popular Plug-ins

Email and Messaging

Graphical Mail Clients

Evolution

Flexible Email & Groupware Tool
Used For
- Email Access
- Maintain a Calendar, Tasklist and Contacts Database

Thunderbird

Standalone Mozilla Email Client
Used For
- Email Access
- Usenet and RSS Supports

Security and Anti-spam Features:

Evolution and Thunderbird both support the Bayesian Spam Fileters.
Evolution and Thunderbird both allows emails to be signed and encrypted.
Evolution integrates supports for the GPG (GNU Privacy Guard) utility for this purpose.
By Default, Thunderbird uses S/MIME for this purpose but use GPG with the help of the plugin called EnigMail.

Non-GUI Mail Clients

Mutt

Mappable Hotkeys
Highly Configurable
Context Sensitive Help with ?
Message Threading & Colorizing
GNU Privacy Guard (GPG) Integration
Supports POP, IMAP and LocalMailboxes

Examples:

You Can Read One Mailbox (POP Account, IMAP Account or Local Mailbox) At A Time.

# Start The Local Mailbox
[mitesh@Matrix ~]$ mutt

# The mutt -f Starts The Specified Mailbox
[mitesh@Matrix ~]$ mutt -f imaps://user@server

Note!: You Can Change Which Mailbox Mutt Viewed By Default, By Altering Its Configuration File ~/.muttrc.

Open SSH - Secure Remote Shell

SSH Allows Remote Logins & Remote Command Execution Via A Secure Encrypted Connections.

Syntax:

ssh [user@]hostname
ssh [user@]hostname command

Examples:

[mitesh@Matrix ~]$ ssh localhost
[mitesh@Matrix ~]$ ssh root@bluehost.com

[mitesh@Matrix ~]$ ssh neo@localhost 'df -h'
neo@localhost's password:

Filesystem            		Size  Used Avail Use% Mounted on
/dev/mapper/vg_Matrix-lv_root	 50G  2.4G   45G   6% /
tmpfs                 		495M  472K  494M   1% /dev/shm
/dev/sda1             		485M   30M  430M   7% /boot
/dev/mapper/vg_Matrix-lv_home	 59G  3.2G   53G   6% /home

scp - Secure File Transfer

The scp works like cp command.
The scp is a secure remote file copy program.

Syntax:

scp [OPTIONS] [[user@]host1:]file1... [[user@]host2:]file2

* Options:
-r(recursive):          Recursively copy an entire directory tree
-p(preserve):           Preserve the permissions, ownership, and time stamps

Examples:

# Download the process.log file
[mitesh@Matrix ~]$ scp neo@localhost:process.log .
neo@localhost's password:
process.log                                        100% 8843     8.6KB/s   00:00

# Upload the userstat.log file
[mitesh@Matrix ~]$ scp userstat.log neo@localhost:.
neo@localhost\'s password:
userstat.log                                        100% 8843     8.6KB/s   00:00

rsync - Efficient File Sync

The rsync is a faster than scp.
The rsync copies the difference in like files.
The rsync uses a secure ssh connections for transport the files.
The rsync is a fast, versatile, remote (and local) file-copying tool.

Examples:

[mitesh@Matrix ~]$ rsync --progress neo@localhost:file1 .
neo@localhost's password:
file1
55 100%   53.71kB/s    0:00:00 (xfer#1, to-check=0/1)

sent 36 bytes  received 129 bytes  36.67 bytes/sec
total size is 55  speedup is 0.33

[mitesh@Matrix ~]$ cat file1
Hello Linux!
Welcome to the OSS!

Open SSH Keybased Authentication

SSH Allows You To Authenticate Using The Private-Public Key Schema.
Optional, Password less, But Still Secure Authentication

Uses Two Keys Generated By The ssh-keygen

Private Key
- Private Key Stay On Your System
- Usually Passphrase Protected (Recommended)
Public Key
- Public Key Is Copied To The Destination With ssh-copy-id
- By Default ssh-copy-id copy the ~/.ssh/id_rsa.pub

Syntax:

ssh-copy-id [user@]hostname

Examples:

ssh-copy-id -i ~/.ssh/identity.pub [user@]hostname
ssh-copy-id -i ~/.ssh/id_rsa.pub [user@]hostname
ssh-copy-id -i ~/.ssh/id_dsa.pub [user@]hostname

NOTE!: Older system may not have ssh-copy-id command
Which will require you to manually copy your public keys to the destination system,
And append it to the ~/.ssh/authorized_keys file, or create the file if it does not exist.
The ~/.ssh/authorized_keys file must be readable by you. Otherwise ssh will ignore it.

Structure Of ssh-keygen

/---------------------------------------------------------------\
|								|
|				identity	Private	600	|
|			RSA1					|
|				identity.pub	Public	644	|
|								|
|	ssh-keygen						|
|								|
|				id_rsa		Private	600	|
|			RSA					|
|				id_rsa.pub	Public	644	|
|								|
|				id_dsa		Private	600	|
|			DSA					|
|				id_dsa.pub	Public	644	|
|								|
\---------------------------------------------------------------/

Examples:

# Generate Protocol2 RSA Key Pairs
[mitesh@Matrix ~]$ ssh-keygen

# Generate Protocol2 DSA Key Pairs
[mitesh@Matrix ~]$ ssh-keygen -t dsa

# Generate Protocol1 Key Pairs
[mitesh@Matrix ~]$ ssh-keygen -t rsa1

NOTE!: By Default ssh-keygen Generates Protocol2 RSA Key Pairs.

ssh-agent

If you created your private key with a passphrase, which is highly recommended for the security reasons, Then whenever the key is used to connect to the other machines, you must type your passphrase.
An Authentication Agent Stores The Decrypted Private Keys
Thus, Passphrase only need to be entered once.
In GNOME Authentication Agent is provided automatically.
Otherwise, You will need to create a Agent-Managed Shell with ssh-agent command

[mitesh@Matrix ~]$ ssh-agent bash
[mitesh@Matrix ~]$

The Keys are added to the Agent with ssh-add command
If no filename is specified, The Keys stored in ~/.ssh/id_rsa and ~/.ssh/id_dsa will be used
You can view the list of stored keys by running

[mitesh@Matrix ~]$ ssh-add -l

NOTE!: When you are finished, Just type exit to return your original shell.
When the Agent is terminated, All your keys are forgotten.

FTP Clients

Several FTP Clients are availables such as sftp, lftp, lftpget, gftp and many more.

sftp

Interactive Secure File Transfer Program.
The sftp uses a secure ssh connections for transport the files.

lftp:

More Featureful File Transfer Program.

Examples:

[mitesh@Matrix ~]$ lftp ftp.example.com
[mitesh@Matrix ~]$ lftp -u joe ftp.example.com

lftpget

Non-interactive File Transfer Program.

Examples:

[mitesh@Matrix ~]$ lftpget ftp://ftp.example.com/pub/file.txt

gftp

Graphical File Transfer Program.
Applications -> Internet -> gFTP
Allows Drag and Drop Transfer
Anonymous or Authenticated Access
Optional Secure Transfer vis SSH (sftp)

SMB Clients

FTP Like Client To Access SMB/CIFS Resources On Server
SMB Clients are used to access the shared resources on the MS Windows Network

Options:

-W:	Workgroup or Domain
-U:	Username
-N:	Suppress password prompt (Useful when accessing a service that does not require a password)

File Transfer with Nautilus

Nautilus are also used to access the remote file shares.
Places -> Connect to Server
Allows Drag and Drop File Transfer
Graphically Browse With Multiple Protocols
Suported Connection Types:
SSH
FTP
SFTP
WebDAV (HTTP)
Secure WebDAV (HTTPS)
Microsoft Windows Shares

Nautilus URL

ftp://ftp.example.com		|	Connects via ftp to ftp.example.com
sftp://user@ftp.example.com	|	Same as above, but connecting securely via ssh as user

smb://				|	List all available SMB Servers
smb://example			|	List SMB Share on example server
smb://user@example		|	Same as above but authenticate as user

Xorg Clients

One Of The Most Important Features Of Xorg Is Its Client/Server Architecture, That Makes Any Graphical Application On Linux System Completely Network Transparent.
That Means You Can Start Any Graphical Application On The Remote System & That Application Displayed On The Local System.
The Graphical Application Running In This Way
Affects Files On The Remote System
Take Up Resources (Cpu Cycles, Memory, Etc) On The Remote System
And That Graphical Application Only Displayed On The Local System

Note!: All Graphical Applications Are X Clients & Connects To The Remote X Server Via TCP/IP
By Default, The Data Transfer Is Not Encrypted But Can Be Tunneled Securely Over An SSH Connection

ssh -X [user@]hostname xterm &

Network Diagnostic Tools

ping

Detects If It Is Possible To Communicate With Other Systems.
Many System No Longer Respond To The Pings.

host

DNS Lookup Utility.
It is normally used to convert Hostnames to IP addresses and vice versa.

dig

DNS Lookup Utility.
Similar to host but greater in details.

netstat

Provides a Number Of Network Statistics.

traceroute

Display The List Of Computers(IP Addresses) Through Which The Packet Is Passed To Reach Their Destination.

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Web Clients

Links

Wget

Google Chrome/Firefox

Email and Messaging

Graphical Mail Clients

Evolution

Thunderbird

Non-GUI Mail Clients

Mutt

Open SSH - Secure Remote Shell

scp - Secure File Transfer

rsync - Efficient File Sync

Open SSH Keybased Authentication

ssh-agent

FTP Clients

sftp

lftp:

lftpget

gftp

SMB Clients

File Transfer with Nautilus

Xorg Clients

Network Diagnostic Tools

ping

host

dig

netstat

traceroute

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