Linux ssh and Dropbear

Telnet: Telnet protocol

Using C/S architecture, clear text is used throughout.

The application layer protocol, which works on TCP 23 ports.

S:telnet Server

C:telnet Client

Ssh:secure Shell

The application layer protocol, which works on TPC 22 Port.

Both the communication process and the authentication process are encrypted, based on the host authentication.

User authentication process Encryption

Data transfer Process Encryption

Host key Hostkey:

Asymmetric encryption

Secert Key

Public key

OpenSSH

Server side: sshd

Configuration file:/etc/ssh/sshd_config

Client: SSH

Configuration file:/etc/ssh/ssh_config

#ssh-keygen [OPTION] key generator

[OPTION]

-T TYPE Specifies the encryption method, commonly used for RSA|DSA

-F keyfile Specifies the private key file.

-P ' PASSWORD ' specifies the password for the encrypted private key, ' indicates a blank password.

The generated key is stored in:

/home/username/.ssh/id_rsa the generated private key

/home/username/.ssh/id_rsa.pub generated Public key

Note: The permissions for the. SSH folder can only be 700!

The generated public key is saved to the relevant file in the home directory of the remote host username and can only be appended and not overwritten:

/home/username/.ssh/authorized_keys

Or

/home/username/.ssh/authorized_keys2

The permissions for the file are 600!

For example:

#ssh-keygen-t RSA

#scp/root/.ssh/id_rsa.pub [Email protected]:/tmp

#ssh [email protected] ' cat/tmp/id_rsa.pub >>/home/hadoop/.ssh/authroized_keys '

Or

#ssh-keygen-t rsa-f. Ssh/id_rsa-p "

#ssh-copy-id-i [email protected]

#ssh-copy-id [OPTION] [[Email protected]]host transfer the public key to a remote server

[OPTION]

-I pubkeyfile specifying a public key file

For example:

#ssh-copy-id-i. Ssh/authorized_keys [Email protected]

#scp [OPTION] SRC DEST cross-Host secure Replication tool.

[OPTION]

-R recursion

-A All

Src

[Email protected]:D IR

Localdir

DEST

[Email protected]:D IR

Localdir

For example:

#scp/root/busybox.tar.gz [Email protected]:/home/hadoop/

#scp [Email protected]:/home/hadoop/busybox.tar.gz/root/

#ssh [OPTION] [[email protected]]host ' COMMAND '

[OPTION]

-L USERNAME HOST

To store files from the host key accepted by the server:

/home/username/.ssh/kown_hosts

Dropbear: Embedded system-specific SSH server and client Tools

Server side: Dropbear

Key Generation tool:

Dropbearkey

Client: Dbclient

Dropbear using Nsswitch for name resolution by default

Nsswitch Required Documents:

/etc/nsswitch.conf

/lib/libnss_file*

/usr/lib/libnss3.so

/usr/lib/libnss.file*

Dropbear or checks to see if the default shell is the security shell of the current system when the user logs on. The security shell is defined within the/etc/shells.

Host key default location:

/etc/dropbear/

Dorpbear_rsa_host_key

Variable length, is a multiple of 8, the default is 1024

Dorpbear_dss_host_key

Fixed length, default is 1024

#dropbearkey [OPTION]

-T TYPE RSA|DSA

-F KeyFile

-S SIZE

This article is from "Small Private blog" blog, please be sure to keep this source http://ggvylf.blog.51cto.com/784661/1616796

Linux ssh and Dropbear