Originally posted by: SystemAdmin

Hi,

I have AIX 5.2 host details of which are given below --

1. oslevel -s

5200-08-00

1. lslpp -l | grep ssh

openssh.base.client 4.7.0.5201 COMMITTED Open Secure Shell Commands
openssh.base.server 4.7.0.5201 COMMITTED Open Secure Shell Server
openssh.license 4.7.0.5201 COMMITTED Open Secure Shell License
openssh.man.en_US 4.7.0.5201 COMMITTED Open Secure Shell
openssh.base.client 4.7.0.5201 COMMITTED Open Secure Shell Commands
openssh.base.server 4.7.0.5201 COMMITTED Open Secure Shell Server

1. lssrc -g ssh

Subsystem Group PID Status
sshd ssh 409784 active

1. cat /etc/ssh/sshd_config
2. $OpenBSD: sshd_config,v 1.75 2007/03/19 01:01:29 djm Exp $

1. This is the sshd server system-wide configuration file. See
2. sshd_config(5) for more information.

1. This sshd was compiled with PATH=/usr/bin:/bin:/usr/sbin:/sbin

1. The strategy used for options in the default sshd_config shipped with
2. OpenSSH is to specify options with their default value where
3. possible, but leave them commented. Uncommented options change a
4. default value.

Port 22
#AddressFamily any
#ListenAddress 0.0.0.0
#ListenAddress ::

1. Disable legacy (protocol version 1) support in the server for new
2. installations. In future the default will change to require explicit
3. activation of protocol 1

Protocol 2

1. HostKey for protocol version 1

#HostKey /etc/ssh/ssh_host_key

1. HostKeys for protocol version 2

#HostKey /etc/ssh/ssh_host_rsa_key
#HostKey /etc/ssh/ssh_host_dsa_key

1. Lifetime and size of ephemeral version 1 server key

#KeyRegenerationInterval 1h
#ServerKeyBits 768

1. Logging
2. obsoletes QuietMode and FascistLogging

#SyslogFacility AUTH
#LogLevel INFO

1. Authentication:

#LoginGraceTime 2m
#PermitRootLogin yes
#StrictModes yes
#MaxAuthTries 6

#RSAAuthentication yes
#PubkeyAuthentication yes
#AuthorizedKeysFile .ssh/authorized_keys

1. For this to work you will also need host keys in /etc/ssh/ssh_known_hosts

#RhostsRSAAuthentication no

1. similar for protocol version 2

#HostbasedAuthentication no

1. Change to yes if you don't trust ~/.ssh/known_hosts for
2. RhostsRSAAuthentication and HostbasedAuthentication

#IgnoreUserKnownHosts no

1. Don't read the user's ~/.rhosts and ~/.shosts files

#IgnoreRhosts yes

1. To disable tunneled clear text passwords, change to no here!

#PasswordAuthentication yes
#PermitEmptyPasswords no

1. Change to no to disable s/key passwords

#ChallengeResponseAuthentication yes

1. Kerberos options

#KerberosAuthentication no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes
#KerberosGetAFSToken no

1. GSSAPI options

#GSSAPIAuthentication no
#GSSAPICleanupCredentials yes

1. Set this to 'yes' to enable PAM authentication, account processing,
2. and session processing. If this is enabled, PAM authentication will
3. be allowed through the ChallengeResponseAuthentication and
4. PasswordAuthentication. Depending on your PAM configuration,
5. PAM authentication via ChallengeResponseAuthentication may bypass
6. the setting of "PermitRootLogin without-password".
7. If you just want the PAM account and session checks to run without
8. PAM authentication, then enable this but set PasswordAuthentication
9. and ChallengeResponseAuthentication to 'no'.

#UsePAM no

#AllowTcpForwarding yes
#GatewayPorts no
#X11Forwarding no
#X11DisplayOffset 10
#X11UseLocalhost yes
#PrintMotd yes
#PrintLastLog yes
#TCPKeepAlive yes
#UseLogin no
#UsePrivilegeSeparation yes
#PermitUserEnvironment no
#Compression delayed
#ClientAliveInterval 0
#ClientAliveCountMax 3
#UseDNS yes
#PidFile /var/run/sshd.pid
#MaxStartups 10
#PermitTunnel no

1. no default banner path

Banner /etc/ssh/ssh_banner

1. override default of no subsystems

Subsystem sftp /usr/sbin/sftp-server

1. Example of overriding settings on a per-user basis

#Match User anoncvs

1. X11Forwarding no
2. AllowTcpForwarding no
3. ForceCommand cvs server

PROBLEM : While being logged in to another host which is on 5300-05-06, if I try to connect to the previous host running on 5200-08-00, I receive the following error message --

Server unexpectedly closed network connection.
OR
Connection to <HOSTNAME> closed by remote host.
Connection to <HOSTNAME> closed.

The host from which I'm trying to connect to AIX 5.2 server is having following OpenSSH filesets installed --

# lslpp -l | grep ssh
openssh.base.client 4.7.0.5302 COMMITTED Open Secure Shell Commands
openssh.base.server 4.7.0.5302 COMMITTED Open Secure Shell Server
openssh.license 4.7.0.5302 COMMITTED Open Secure Shell License
openssh.man.en_US 4.7.0.5302 COMMITTED Open Secure Shell
openssh.base.client 4.7.0.5302 COMMITTED Open Secure Shell Commands
openssh.base.server 4.7.0.5302 COMMITTED Open Secure Shell Server

Kindly suggest what could be the possible problem due to which I'm not able to connect.
Thanks in advance...

ATUL
#AIX-Forum