Questions[sshd](ubuntu)

I have a machine running Ubuntu 18.04 LTS where I cannot seem to get SSH Server working.

I installed SSHServer using:

sudo apt install openssh-server

but I am getting the following when I try to start and / or check the status:

sudo systemctl start sshd

Failed to start sshd.service: Unit sshd.service not found.

.

sudo systemctl status sshd

Unit sshd.service could not be found.

I figured I must have done something wrong (typo?) when I installed, so I tried to install again thus:

sudo apt install openssh-server

to which I get:

Reading package lists... Done
Building dependency tree       
Reading state information... Done
openssh-server is already the newest version (1:7.6p1-4ubuntu0.3).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

So, it appears it is installed, but for some reason Ubuntu cannot find it.

I am not sure where to go from here, so any suggestions would be welcome.

Thanks,

Alan.

My problem is : I developed successfully RSA Key based ssh login on board from system. When a client logs in for the first time, ask about private key and passphrase also which works fine. In second time login, ssh doesn't ask private key or password, directly login on board.

Client side use Ubuntu 16.04 and on board customizes Ubuntu.

First time login with below command:

ssh -i ~/.ssh/id_rsa user@board_ip //works fine

Second time:

ssh user@board_ip //never ask password and public key - problem

First time:

ssh user@board_ip //not able to login without key - works fine

As per my understanding, I made a mistake in the sshd_config file on the board. I played with below settings but failed it all the time.

StrictModes yes
RSAAuthentication yes
PubkeyAuthentication yes
#PasswordAuthentication yes                                            
PermitEmptyPasswords no

Project requirement is secure login, mainly on ssh. To achive more security SSH password based login, we shifted to key based login. As explain above after change all configuration. SSH login require private key and password also. After logout and after sometime login again, ssh doesn't require key or password, project requirement need key and password each and everytime.

I'm using an Ubuntu 14.04.4 server, running sshd OpenSSH_6.6.1p1 Ubuntu-2ubuntu2.8, OpenSSL 1.0.1f 6 Jan 2014.

The server is also running Intel's DPDK framework, to develop network software; part of doing that involves bringing down interfaces at the Linux level to bind them to DPDK. However, the network interface used to ssh from the outside is never brought up or down, only others are touched.

Most of the time ssh works fine, but once every few days it stops working; ssh sessions are interrupted, and trying to reconnect by running ssh -v halts at the message Local version string SSH-2.0 ... (i.e. the client can establish a connection, it's the SSH part that fails).
Directly connecting to the machine doesn't work either, the command-line interface doesn't show up, just a blank screen.
TCP connections can be established, and the machine still answers pings.

This is pretty annoying, since the server then needs to be rebooted.

I enabled debug3 logs on the server, and the log in /var/log/auth.log when a client tries (and fails) to connect look like this:

sshd[1688]: debug3: fd 5 is not O_NONBLOCK
sshd[1688]: debug1: Forked child 39149.
sshd[1688]: debug3: send_rexec_state: entering fd = 13 config len 724
sshd[1688]: debug3: ssh_msg_send: type 0
sshd[1688]: debug3: send_rexec_state: done
sshd[39149]: debug3: oom_adjust_restore
sshd[39149]: Set /proc/self/oom_score_adj to 0
sshd[39149]: debug1: rexec start in 5 out 5 newsock 5 pipe 12 sock 13

This log doesn't seem any different from the one for successful connections, except that it stops there, whereas successful connections continue (the next line is then debug1: inetd sockets after dupping: ...).

The problem seems to arise right when an interface is bound or unbound from DPDK.

What could be causing this? Are there workarounds?

Please know I am no sysadmin.

Yesterday I re-installed UBUNTU 12.04 LTS - running 3.2.0-33-generic-pae.

I have worked for hours trying to install vsftpd to no avail, and now find myself trying to configure sftp via the sshd, if that makes sense.

ps -ef |grep ssh
00:00:00 /usr/bin/ssh-agent /usr/bin/dbus-launch --exit-with-session gnome-session --session=ubuntu
NOTICE THE SIZE of my sshd_config
ls -la /etc/ssh/

-rw-r--r-- 1 root root 125749 Apr  2  2012 moduli
-rw-r--r-- 1 root root   1669 Nov 18 11:58 ssh_config
-rw-r--r-- 1 root root   1668 Nov 18 11:47 ssh_config~
-rw-r--r-- 1 root root     20 Nov 18 11:25 sshd_config
-rw------- 1 root root    672 Nov 18 11:29 ssh_host_dsa_key
-rw-r--r-- 1 root root    598 Nov 18 11:29 ssh_host_dsa_key.pub
-rw------- 1 root root    227 Nov 18 11:29 ssh_host_ecdsa_key
-rw-r--r-- 1 root root    170 Nov 18 11:29 ssh_host_ecdsa_key.pub
-rw------- 1 root root    973 Nov 18 11:29 ssh_host_key
-rw-r--r-- 1 root root    638 Nov 18 11:29 ssh_host_key.pub
-rw------- 1 root root   1675 Nov 18 11:29 ssh_host_rsa_key
-rw-r--r-- 1 root root    390 Nov 18 11:29 ssh_host_rsa_key.pub
-rw-r--r-- 1 root root    302 Jan 10  2011 ssh_import_id

when I sudo /etc/init.d/ssh restart it starts the ssh, but why not the sshd?

Thank You, David

After installing openssh-server, the server start every time I boot. If I want it to be manual what do I need to do?

In version 0.6.7+ of upstart I would add a "manual" stanza to the job file.

10.04 has upstart 0.6.5-8. What is the preferred way to disable ssh from starting automatically in this case?