I installed Rhel 7 in my laptop and i could not start the sshd session. It always says that as below :
sshd-keygen: generating ssh2 rsa host key failed.

I tried to generate the key manually, but it not works.
Due to this am unable to connect the session with putty. Could anyone help me please.

please provide the exact commands you used, and everything they returned. please use the "-v" switch (=verbose) for ssh-keygen.
and some general info, in as much detail as you can.

I understood that in deafault the keys should be generated in /etc/ssh dir while installing. But i could not find the keys available in the dir.
I tried to start the sshd to login with putty and it thrown the error

systemctl status sshd ---> gives
Active: activating (auto-restart)
process: 12234 Execstartpre=/usr/sbin/ssh-keygen (code=exited, status=1/Failure)

sshd.service: control process exited,
Failed to start openssh server daemon.
unit sshd.service entered failed state.

When i used the command sshd -t
could not load host key: /etc/ssh/ssh/ssh_host_rsa_key
could not load host key: /etc/ssh/ssh/ssh_host_ecdsa_key

sshd-keygen -t rsa --------> gives
Generating ssh2 rsa host key: [FAILED]

Please see the LQ Rules about text-speak..and about not using it.

And you still haven't told us what version/distro of Linux you're using, so it's hard to provide details. Putty doesn't enter into this, since it's just a terminal client, and it sounds like you don't have SSH running on your Linux system. Are you running as root when you try to start that service? If you're not...it won't work.

Hi, Am sorry.

Am using Toshiba Laptop -- 4GB RAM with Windows 10.
Installed Redhat Linux 7 through Orcale VM Virtual Box Manager. The sshd process is not running and am unable to start it though.

Am trying to start the sshd service through Root. Please let me know, if you required any additional information.

you should have root privileges to start the daemon, but everything else you should do as a normal user, afaik.
generating & storing the keys in /etc/ssh seems extremely wrong to me.
i'm not surprised sshd refuses to start if you've been messing around in its system-wide config directory.
ssh is very particular about file permission (and a good thing too! after all you're opening your machine to the world!).
i suggest you check out a few of the ~100.000 ssh tutorials out there.

ps:
i still don't see how you are (re)starting the sshd, unless you are rebooting your machine after every change?
have you ever issued "sudo systemctl restart sshd"?

Thanks Bro,

I used "systemctl restart sshd" through root. I executed "sudo systemctl restart sshd" and receives the same error.
job for sshd.service failed. See 'systemctl status ssdh.service' and 'journalctl -xn' for details.



systemctl status sshd.service gives
Active: activating (auto-restart)
process: 12234 Execstartpre=/usr/sbin/ssh-keygen (code=exited, status=1/Failure)

sshd.service: control process exited,
Failed to start openssh server daemon.
unit sshd.service entered failed state.


journalctl -xn ---> says

Unit sshd.service has begun starting up.
sshd-keygen: Generating SSH2 RSA host key: [failed]
sshd.service: control process exited, code=exit.
Subject: Unit sshd.service has failed.
define-by: systemd
Unit sshd.service has failed.
The result is failed.

i'm not your bro.

let's recap:
you are running the sshd daemon on your rhel server.
you want to connect to this server from some other machine via ssh. (putty suggests windows?)
for that you have to generate a key pair on the client machine, not the server (if you want passwordless login).

i have no clue why your sshd wants to generate keys upon startup, but i suspect it's because you've been messing around in /etc/ssh.
i could be wrong though.
i'm not using rhel.

i suggest you find out if it's normal that sshd on rhel wants to run a command called "sshd-keygen" (on my debian server there's no such command, only ssh-keygen).
after that you should find a good ssh tutorial, and understand what is the server side and what is the client side, amongst other things.