topic Re: Linux 7.2 connection refused in Operating System - Linux

Linux 7.2 connection refused

Carlos Munoz Lopez — Tue, 13 Jan 2004 16:25:29 GMT

Hi guys! I'm having problems with remote connection using telnet and ssh. When I try to use telnet to connect to my server running Linux RedHat 7.2 it display all the normal information (connection established to xx.xx.xx.xx) but when I enter the username (for instance root) and the password it says Login incorrect, even when the password is correct. Another problem is with ssh, when I try to connect to the server it displays the following message:

OpenSSH_3.5p1, SSH protocols 1.5/2.0, OpenSSL 0x0090701f
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Rhosts Authentication disabled, originating port will not be trusted.
debug1: ssh_connect: needpriv 0
debug1: Connecting to 10.20.30.40 [10.20.3.40] port 22.
debug1: Connection established.
debug1: identity file /root/.ssh/identity type -1
debug1: identity file /root/.ssh/id_rsa type -1
debug1: identity file /root/.ssh/id_dsa type -1
debug1: Remote protocol version 1.99, remote software version OpenSSH_2.9p2
debug1: match: OpenSSH_2.9p2 pat OpenSSH_2.*,OpenSSH_3.0*,OpenSSH_3.1*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_3.5p1
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-cbc hmac-md5 none
debug1: kex: client->server aes128-cbc hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: dh_gen_key: priv key bits set: 128/256
debug1: bits set: 1057/2049
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that the RSA host key has just been changed.
The fingerprint for the RSA key sent by the remote host is
e5:8f:e6:1d:d3:95:25:d7:91:af:0a:1b:b5:58:ed:7f.
Please contact your system administrator.
Add correct host key in /root/.ssh/known_hosts to get rid of this message.
Offending key in /root/.ssh/known_hosts:3
RSA host key for 10.20.30.40 has changed and you have requested strict checking.
Host key verification failed.
debug1: Calling cleanup 0x80674d0(0x0)

What do I have to change in order to connect to the server??

And one last problem is with the ftp, how can I configure an ftp server, specially a secure one, using sftp??? I would like some help on theses issues.

Re: Linux 7.2 connection refused

Sridhar Bhaskarla — Tue, 13 Jan 2004 16:38:01 GMT

1. Make sure your linux system is allowing you to login directly as root.

2. Edit /root/.ssh/known_hosts on the local server and remove the line that has the Linux system's IP and try ssh.

3. Try with a different user and see if it is allowing.

Usually ssh packages are supplied with sftp-server. If you have it, then you can use it.

-Sri

Re: Linux 7.2 connection refused

Steven E. Protter — Tue, 13 Jan 2004 16:50:25 GMT

I see a version mismatch in your logs.

Some entries are for openssh 3.5, others for openssh 3.0

I further know that openssh 3.1 came with Red Hat 7.3.

I'd say you are the victim of a failed upgrade to openssh 3.5

Probably you need to back out the upgrade and reinstall it.

SEP

Re: Linux 7.2 connection refused

Carlos Munoz Lopez — Tue, 13 Jan 2004 16:56:23 GMT

It's strange because it wasn't an upgrade, it wasn't previously installed, the system marked as a clean installation.

I tried your suggestion with the /root/.ssh/known_hosts, but it didn't work. Do I have to change something in the /etc/ssh/ssh_conf??

Re: Linux 7.2 connection refused

Sridhar Bhaskarla — Tue, 13 Jan 2004 17:02:14 GMT

I am not sure if it is due to version mismatch.

What error are you getting now after removing the host key from known_hosts?. It's the third line. Or move known_hosts as known_hosts.old and try.

It shoudl prompt you login. If you are not able to login even then, I believe Linux is not allowing direct login for root. Look at the syslog on the Linux box for any error information.

-Sri

Re: Linux 7.2 connection refused

Steven E. Protter — Tue, 13 Jan 2004 17:03:39 GMT

a rebuild of .ssh/known_hosts seems the next logical step.

What I saw may merely be unmodified pieces of the software untouched by upgrades.

SEP

Re: Linux 7.2 connection refused

Carlos Munoz Lopez — Tue, 13 Jan 2004 17:13:54 GMT

I tried to comment some lines in the /etc/ssh/sshd_config file, and it worked, the lines commented were:

Port 22
ListenAddress 0.0.0.0
HostKey /etc/ssh/ssh_host_key
HostKey /etc/ssh/ssh_host_rsa_key
HostKey /etc/ssh/ssh_host_dsa_key
ServerKeyBit 768

I tried the connection from another Linux server and it was successful, but when I tried it from my PC using a terminal emulator it didn't work. I don't know what is going on?