SSH

how to increase ssh time (putty)

create config file under .ssh

[root@localhost ~]# vim .ssh/config 

add below entry under config file

Host *

ServerAliveInterval 60

wq!

reload or restart sshd service

[root@Localhost Desktop]# rpm -qa | grep ssh  - package check not found

[root@Localhost Desktop]# yum install *ssh*   or    yum install openssh*

[root@Localhost Desktop]# rpm -qa | grep ssh  - package check after installation

libssh2-docs-1.4.2-1.el6_6.1.x86_64

trilead-ssh2-213-6.2.el6.noarch

libssh2-devel-1.4.2-1.el6_6.1.x86_64

openssh-askpass-5.3p1-112.el6_7.x86_64

pam_ssh_agent_auth-0.9.3-112.el6_7.x86_64

openssh-5.3p1-112.el6_7.x86_64

openssh-clients-5.3p1-112.el6_7.x86_64

ksshaskpass-0.5.1-4.1.el6.x86_64

openssh-ldap-5.3p1-112.el6_7.x86_64

openssh-server-5.3p1-112.el6_7.x86_64

trilead-ssh2-javadoc-213-6.2.el6.noarch

libssh2-1.4.2-1.el6_6.1.x86_64

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[root@Localhost Desktop]# /etc/init.d/sshd restart   ---------start or restart ssh server

Stopping sshd:                                             [  OK  ]

Starting sshd:                                             [  OK  ]

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[root@Localhost Desktop]# telnet 127.0.0.1 22   ----check port status

[root@Localhost Desktop]# nc localhost 22

[root@Localhost Desktop]# netstat -tulnp | grep -i 22

tcp        0      0 0.0.0.0:22                  0.0.0.0:*                   LISTEN      10291/sshd         

tcp        0      0 :::22                       :::*                        LISTEN      10291/sshd         

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[root@Localhost Desktop]# /etc/init.d/sshd status   ----- check SSH status

openssh-daemon (pid  10291) is running...

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[root@Localhost Desktop]# ps -ef | grep -i sshd   ----- check server & port

root     10291     1  0 07:11 ?        00:00:00 /usr/sbin/sshd

root     10332  7657  0 07:19 pts/0    00:00:00 grep -i sshd

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[root@Localhost Desktop]# vi /etc/sshd/ --root path of SSH

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[root@Localhost ~]# vim /etc/ssh/sshd_config   --------------SSH configuration fil e

#Port 22 -----------------------port settings, we can manage

# Authentication:

PermitRootLogin no   -----------uncomment and type no for disable ssh root login 

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[root@Localhost ~]# /etc/init.d/sshd reload   ---- reload service

Reloading sshd:                                            [  OK  ]

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SERVER		CLIENT
rpm –qa | grep –i ssh		no need to installed ssh service
yum install *ssh*		ssh – client / command / utitlity
Ssh-*  ---not work		( usr/bin/ssh ) – just a command
used *ssh* - package name is – openssh		ssh 192.168.1.14 – (server ip )
Yum install openssh*		If stop sshd service but ssh cmd is working
/etc/init.d/sshd used tab tab restart		Port - 22
/etc/init.d/sshd restart		When used for connect server to used random port
ssh port - 22
telnet localhost 22		ssh < server ip >
nc localhost 22		ssh 192.168.1.14
netstat – tulnp | grep –i 22		its refers /etc.service file for port  to connect server side
/etc/init.d/sshd status
ps –ef | grep –i sshd – check server & port		1 ) # ssh champu@192.168.1.14 we can login through user also 2 ) #ssh 192.168.1.14 –l champu
Always disable root login for ssh
OS Harening  -- 1 step
vi /etc/sshd/ --root path		Copy files on server
vi /etc/sshd/sshd_config  –configuration file of sshd PermitRootLogin no – uncommnet (# ) & type no for disable root login		scp /mnt/* champu@192.168.1.14:/opt/
		rsync /mnt/* champu@192.168.1.14:/opt/
/etc/init.d/sshd reload  - reload service
we can change sshd port example : 22 change poer : 222		After change port – access ssh
		ssh 192.168.1.14 –p 222
		Change in /etc/service file
HOW TO SSH WORK 1) – client request to server 2) server send public key  --- public key travel on network 3) client send public key   --- public key travel on network 4) Server send privet key ( give access to client )

Encrymtion type

1 - MD5
2 - SNA
3 - RSA -- Rivert Shamim Adelmen -- name of persons
4 - DSA

Ssh generate two keys on server

1) ---    public key

2) ---    private key

SSH used RSA encryption  ----- Rivert Shamim Adelmen

SERVER		CLIENT
#cd /etc/ssh		Public key store in below path
#ls		/root/.ssh/know_hosts – public key
Public_key and private_key		/champu/.ssh/know_hosts – public key