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Questions tagged [openssh]

Questions about the OpenSSH implementation of the ssh protocol.

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Openssh Questions

I was reading about OpenSSH and I have the following questions: What is the difference between ssh and slogin? What is the difference between scp and sftp? Does sshd (on server side) provide separate ...
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0answers
50 views

sshd_config Match rule to catch target Host

I have a jumpbox server for SSH with an external IP that has DNS match with a wildcard - i.e any address with this structure: *.mydomain.com will result with the same IP which is the jumpbox IP. what ...
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37 views

Script not executing with ssh and sshpass

I have a script in my .gitlab-ci.yml which is not being executed. Here's the script: - apk update - apk add --no-cache openssh-client sshpass - sshpass -p "${USER_PASS}" ssh -o ...
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1answer
28 views

OPNsense 19.1 removes root's authorized_keys when reboot / shutdown+turn on

I have an OPNsense 19.1 virtual firewall, which is based on FreeBSD 11.2 HBSD (HardenedBSD). I added it to Ansible Server inventory (with the right configurations), and once copied the PK to that BSD ...
2
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1answer
33 views

OpenSSH: if the server is set to “PasswordAuthentication no” then is there any risk if the *client* is set to “PasswordAuthentication yes”?

For all my servers PasswordAuthentication is set to no in the sshd_config file. This means that only key authentication is allowed. In this situation, is there any risk if PasswordAuthentication is ...
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15 views

ssh-keygen print certificate file in older versions

The version I am using seem to be old and doesn't have the -L option. -L Prints the contents of one or more certificates. Is there an alternative way to do it? The script I'm using basically use ...
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1answer
36 views

Simply adding to SSH known_host without forcing an error?

I have two machines devbox, and gitbox. The second machine, gitbox is a development box that has no shell, and is very locked down just to afford git over ssh (there isn't access to /bin/true even) ...
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1answer
55 views

Is this SSHD config appropriate / secure [closed]

On the latest Debian Stretch I installed an OpenSSH server which I set up under the following conditions. no root login no password authentication / force public key authentication authentication by ...
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28 views

SSH breaking my terminal on unsuccessful command [duplicate]

In a an Scala application running on a remote computer, I've added a call I can make that opens a reverse tunnel to a port on a server with a public IP I can connect to afterwards. The tunneling ...
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0answers
23 views

SSH - root login disabled, password disabled. Still need a complex root password for local sessions?

If this computer's openssh server requires keys for SSH logins, do I still need to have a complex password? Given that this is a private single-user computer in a secure building.
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47 views

OpenSSL Missing Ciphers

I have two instances of RHEL (6.2 and 6.5) both using the same versions of OpenSSL and OpenSSH (albeit different versions). Red Hat Enterprise Linux Server release 6.2 # yum info openssl Installed ...
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32 views

Ubuntu 16.04 - Cannot SSH with root user, login successfully but closed immediately with return code 254?

I could SSH to 1 server with a non-root user. However, I tried to enable root login at /etc/ssh/sshd_config with this content: # Package generated configuration file # See the sshd_config(5) manpage ...
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2answers
71 views

WSL: Keeping ssh private key accessible as long as I don't restart Windows 10 (like the behaviour of pageant)

So far on Windows 10 I used mainly the PuTTy bundle (PuTTygen, Pageant and PuTTy, etc) to SSH into remote Linux machines. I use Pageant as a private key holder to hold to private key (and possible ...
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1answer
31 views

Getting “Enter passphrase for key” for a linux machine from shell script [duplicate]

Context: Want to automate a process which requires a connection to Linux vm machine from code running on AWS cloud. Code Snippet: #!/bin/sh ssh -i LinuxVM.ppk testuser@<ipadress> 'df -h'. ...
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1answer
40 views

what exactly do I need to make my pc an ssh server and connect to it? [closed]

I tried to create ssh server on my pc. It connects well on LAN but over internet it does not. I have tried everything that I can. I can connect to azure server from pc though. I am running arch ...
1
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1answer
41 views

(root) Warning: Identity file /dev/fd/62 not accessible: No such file or directory

Very similar to Failed to open config file '/dev/fd/63', error: No such file or directory for wpa_supplicant except for the fact that I am running as root. bash-4.4# autossh -v -M 0 -4 -o ...
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1answer
119 views

Forward abstract unix socket over SSH?

I've discovered that OpenSSH is capable of forwarding UNIX sockets like this: ssh -R /var/run/program.sock:/var/run/program.sock My question is whether this extends to abstract unix sockets too. I'...
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0answers
205 views

Reverse SSH-Tunnel with Socket

I would like to establish a reverse SSH-tunnel (with OpenSSH_7.4 or newer). The purpose is to allow SSH-connections from a central server to multiple devices whose task it is (among others) to ...
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0answers
27 views

Filezilla EOF SFTP Error

A router is accessible with Putty via SSH. A remote user was a to login from the command-line and scp a file. Attempts to login with Filezilla are met with errors: Error: Received unexpected end-...
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1answer
71 views

Using OpenSSH to create overlay IPv6 network [closed]

If there's a SSH setup like this: Host A -> Host B <- Host C Where Host C is behind a NAT/firewall an opens a reverse tunnel to Host B and Host A connects to Host C via Host B (ProxyCommand). ...
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0answers
189 views

SSH ClientAliveCountMax & ClientAliveInterval not working

I changed the following SSH config (and rebooted the SSH, or even rebooted the server): ClientAliveCountMax 120 ClientAliveInterval 720 LoginGraceTime 300 Problem is that the parameter "...
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0answers
39 views

Why do I keep my SSH connection, after suspending, if I have a window open on the server?

I've noticed this strange behaviour. Everytime when I'm connected to a remote machine, using SSH, and want to go away from my machine (for lunch, for example), I suspend it. And when I type in the ...
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0answers
31 views

SSH terminal messes multiline commands [duplicate]

I am frequently using ssh terminal. If I enter a command that spans multiple lines, the characters which do not fit onto the first line are going to the beginning... not of the next but of the current ...
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1answer
100 views

ssh-keyscan -H returns different keys every time

I'm getting different keys every time I run ssh-keyscan -H some.hostname.example. Why is that? Is the server continuously changing keys? They keys I'm getting from one run seems to work even after a ...
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0answers
22 views

alternative to sshd first-match-only MATCH configuration

Given an openssh (1:7.2p2-4ubuntu2.6 on ubuntu 16.04) installation, I find myself with multiple tiers of groups that I'd like to work with. The way I'm trying to set up the groups is effectively this: ...
2
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1answer
256 views

What encoding is used for the keys when using `ssh-keygen -t rsa`?

When I run: ssh-keygen -t rsa to generate a public/private key pair in files e.g. id_rsa.pub and id_rsa, my understanding is that the public key encodes a prime number p, and the private key encodes ...
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1answer
154 views

use chroot to lock down sftp access without root owning folder

Everything I am reading says that for chroot to work with sftp root has to own the folder. I want to make it so a user can only sftp to a sub-directory in their home folder like /home/user/some/folder....
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1answer
35 views

iptables, vpn server, routing

I set up my server (let's call it server A) firewall so that no input/output rules be allowed, apart from: - incoming ssh conection - outgoing ssh connection This is working well by now! Now, i ...
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0answers
68 views

Require a yubikey AND (publickey OR password) for SSHD auth

I am attempting to configure OpenSSH on a Debian based system to always require a yubikey TOTP AND either a publickey OR password. I realise other combinations are possible through ...
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1answer
506 views

install openssh 7.6 on red hat 7.5 [duplicate]

I have a redhat server 7.5. I have a openssh installed on this server. The openssh is 7.4. I need to upgrade openssh 7.4 to 7.6 AS Nessus, vulnerability scanner scanned this vulnerability (Openssh <...
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1answer
993 views

Upgrade OpenSSH 7.4 to later on RHEL

I have a Red Hat Enterprise Linux server (7.5 x86_64). I have OpenSSH version 7.4. I was asked to upgrade it to a later version for security reasons: Nessus states that OpenSSH should be ugraded from ...
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1answer
192 views

Update OpenSSH on RHEL 5.5

I must update OpenSSH on my RHEL 5.5 because of CVE-2018-15473. My OpenSSH version is OpenSSH_4.3p2 and must be update to OpenSSH_7.9, when i want to do this i get that message when using configure ...
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0answers
59 views

SSH connection failure: processing of forwarded request fails on known_host key

When I attempt a SSH connection between client C and server S (both on the same LAN) the client looks up the server's key in the client user's known_hosts file. In the usual case for connection ...
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2answers
88 views

What are the various levels in ssh -vvv: debug1, debug2, debug3

Is each a different side of the connection or a deeper layer of logging. I am interested because of, for example, this excerpt from a vvv output debug3: send packet: type 30 debug1: expecting ...
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1answer
109 views

How could I debug sshd taking several minutes to start?

I use a VM with ssh and X forwarding to run certain applications. When launching the VirtualBox VM, it takes several minutes for ssh to come online, even though the machine is at the desktop ...
3
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1answer
1k views

OpenSSH Server won't start on orangepi/linux

I am currently doing some testing with an Orange Pi. After doing an update on a fresh install it seems as though the ssh server is no longer able to start itself, and I'm not able to manually start it ...
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86 views

SSH forwarded through modem recently started failing: update

Server host Ubuntu 18.04: Openssh-server/bionic-updates,bionic-security,now 1:7.6p1-4ubuntu0.1 amd64 Modem: Arris Xb6 Tested with clients: Ubuntu 18.10: openssh-client/cosmic,now 1:7.7p1-4 amd64 ...
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1answer
343 views

How do I connect to an SSH server with no ciphers in common? [duplicate]

I'm running Kali Linux with ssh -V of OpenSSH_7.7p1 Debian-3, OpenSSL 1.0.2o 27 Mar 2018. I tried to SSH to a server (a hacking challenge) and got the response Unable to negotiate with ********* port ...
3
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1answer
371 views

SSH only after login?

I've freshly setup a rather standard current Arch Linux and encounter a problem that I can not get a grip on: DHCP service is enabled and network is online (ping succeeds with hostname and IP ...
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votes
1answer
261 views

Troubleshooting ssh connection with RSA key [closed]

Here is what I see in the logs debug1: SSH2_MSG_SERVICE_ACCEPT received debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password debug1: Next authentication method: ...
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0answers
65 views

Remove inactive SSH process (on server) after connection dropped (on client)

I'm using the following command on a client for port tunneling: autossh -M 20000 -4 -N -f -R 18822:localhost:22 <user>@<vps-ip> Sometimes the client would lose connection or power for a ...
2
votes
1answer
106 views

What does `ssh-keygen -r` do if a public key is not specified?

Short Question I'm assuming that ssh-keygen -r hostname uses a default public key. I would have thought that it would default to ~/.ssh/id_rsa.pub, but that does not appear to be the case. So what is ...
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2answers
637 views

SSH Remote port forwarding with multiple ports

For those who worked with ssh port forwarding or for those who have an idea, I managed to create a remote tunnel from my PC to a remote machine(a camera that does not have a public address) through a ...
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1answer
75 views

ssh to docker container breaks after 45 seconds

I have docker running on a synology nas. The nas has a private network (172.17.0.0/16) where docker places the containers. It also has a public facing interface on my lan, call it 10.11.12.10/24. ...
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1answer
82 views

Changing hostname more than once via ~/.ssh/config

I have the following set up in my ~/.ssh/config match host devbox compression yes user hari port 22 hostname 192.168.9.7 match originalhost devbox exec "~/.ssh/check_if_outside_home.sh" ...
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1answer
972 views

ssh to Cisco device not working [duplicate]

I have an issue where my server is not able to ssh to a cisco device after upgrading the server to the latest version. I did a ssh -vvv, I am not sure about two sections. Below are the details : I ...
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1answer
33 views

ssh to a linux box going through 2 servers

I would like to ask for your ideas, we have a somewhat complicated network setup and I need to connect to dozens of linux boxes and sometimes need to do remote reboot on them but before I can even ...
2
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1answer
163 views

How to enable up-arrow command history and command completion in sftp on Gentoo?

When I try to use up-arrow command history via sftp to my CentOS 7 server it just prints ASCII characters to the output instead of recalling recent commands: sftp> ^[[A It's very time consuming ...
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1answer
294 views

show values of an ed22519 private key stored in OpenSSH format

(note this question uses both 'openssh' and 'openssl' in the text, I am not confusing the two.) If I use openssh to general an RSA keypair (ssh-keygen) then I can use 'openssl rsa -in ...' to view ...
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0answers
103 views

Can`t connect through ssh using passwordless technique to centos 7 as user but as root succeeds

I have been trying log in to my centos 7 using the passless technique. First I have generated a public key: ssh-keygen then tried to connect keys with remote: ➜ ~ ssh-copy-id user@xxx.com /usr/...