Several methods of automatic login without password for Linux SSH

1. Automatic Ssh/scp method = =

A is a local host (that is, the machine used to control other hosts);
b is the remote host (that is, the controlled machine server), if the IP is 192.168.60.110;
Systems A and B are all Linux.

Run the command on a:
# ssh-keygen-t RSA (three consecutive returns, i.e. locally generated public and private keys, no password set)
# SSH [email protected] "mkdir. SSH" (need to enter a password)
# SCP ~/.ssh/id_rsa.pub [email protected]:.ssh/id_rsa.pub (need to enter a password)

command on B:
# Touch/root/.ssh/authorized_keys (if this file already exists, skip this one)
# cat/root/.ssh/id_rsa.pub >>/root/.ssh/authorized_keys (append id_rsa.pub content to Authorized_keys)

Back to a machine:

# SSH [email protected] (no password required, login successful)

If agent admitted failure to sign using the key error occurs

On the A machine:

# Ssh-add ~/.ssh/id_rsa

2. Control of n machines automatic login as described above
That requires n-pair keys (keys and public keys), and the Ssh-keygen command can change the name of the key pair, such as:
# ssh-keygen-t RSA
Generating public/private RSA key pair.
Enter file in which to save the key (/ROOT/.SSH/ID_RSA):/root/.ssh/id_rsa_192.168.60.110

So the private key and the public key name are: Id_rsa_192.168.60.110 and id_rsa_192.168.60.110.pub, and then append the contents of the Id_rsa_192.168.60.110.pub file to sever ~/. Ssh/authorized_keys file, finally, specify the local key locally with the-I parameter of the SSH command and log in:
# ssh-i/root/.ssh/id_rsa_192.168.60.110 [email protected]

The SCP is the same.
# scp-i/root/.ssh/id_rsa_192.168.60.110 filename [email protected]:/home/someone

Add two lines in the file. BASHRC, and do the same thing each time without typing such a long command:
Alias Sshcell= ' ssh-i/root/.ssh/id_rsa_192.168.60.110 [email protected] '
Alias scpcell= ' scp-i/root/.ssh/id_rsa_192.168.60.110 filename [email protected]:/home/someone '

In this way, type the instructions directly to implement SSH and SCP auto-login:
# Sshcell
# Scpcell


3. Automatic SSH/SCP Script
If you need to go from a, to B, then to C, then SSH and SCP two times, it is more troublesome.
SSH Automatic Login:
#!/usr/bin/expect-f
Set Timeout 30
Spawn ssh [email protected]
Expect "Password:"
Send "pppppp\r"
Expect "]*"
Send "ssh [email protected]\r"
Expect "Password:"
Send "pppppp\r"
Interact


SCP from a copy file to C:
#!/usr/bin/expect-f
Set Timeout 300
Set file [lindex $argv 0]
Spawn SCP $file [email Protected]:/home/weiqiong
Expect "Password:"
Send "pppppp\r"
Expect "]*"
Spawn ssh [email protected]
Expect "Password:"
Send "pppppp\r"
Expect "]*"
Send "SCP $file [email protected]:/home/weiqiong\r]
Expect "Password:"
Send "pppppp\r"
Expect "]*"
Exit
Interact

SCP copies files from C to a:
#!/usr/bin/expect-f
Set Timeout 300
Set file [lindex $argv 0]
Spawn ssh [email protected]
Expect "Password:"
Send "pppppp\r"
Expect "]*"
Send "SCP [email protected]:/home/weiqiong/$file. \ r]
Expect "Password:"
Send "pppppp\r"
Expect "]*"
Send "exit\r"
Expect "]*"
Spawn SCP [email protected]:/home/weiqiong/$file.
Expect "Password:"
Send "pppppp\r"
Interact

4. Establish SSH/SCP Channel
For example, my machine is a, the intermediary server is B, the target server is C
From a can ssh to B, from B can ssh to C, but a cannot directly SSH to C
Now showing the use of SSH channel technology to transfer files from a directly to C
1. ssh-l1234:c:22 [email protected]
Input B ' s password
(1234 is the idle port of native A, which requires root user rights on a machine, in fact, a channel is established on the native 1234 port)

2. Open a new console and type:
scp-p1234 filename [email protected]:
Input C ' s password

Several methods of automatic login without password for Linux SSH