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Questions tagged [openssh]

Questions about the OpenSSH implementation of the ssh protocol.

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OpenBSD's signify doesn't work on macOS (signify-osx) Sonoma - Could not verify signature

I wish to verifiy a GrapheneOS release I downloaded. This OpenBSD's signify looks like more secure sha512sum. I did not fully understand it. This is what I did: $ brew install signify-osx $ ssh-...
Salinas's user avatar
  • 11
1 vote
0 answers
37 views

OpenSSH with admin user

I am setting up an OpenSSH sFTP server. I want to create a sFTP Admin user that can navigate all the folders and move files. My approach is the following: Create the other users (let's call it user_1)...
Throwaway123's user avatar
0 votes
1 answer
25 views

Can ssh as socks proxy be detected?

I am connecting with web browser (Chromium, Firefox) using socks5 proxy via local port opened by ssh -D <port> <host> (currently openssh 9.8). Sometimes, I experience problems from the ...
lash's user avatar
  • 739
1 vote
1 answer
42 views

How to match IPv6 addresses as a host pattern in ssh_config

My VPS listens to SSH on port 222. On my clients I created a ssh_config such that the non-default port needs not to be explicitly provided on the command line every time. (Some daemons which ...
user2690527's user avatar
2 votes
1 answer
130 views

Configuring sshd directly instead of using "security policy" on RHEL 8

RHEL 8 overrides some sshd settings, so no matter what it has been set in /etc/ssh/sshd_config, the options listed in /etc/crypto-policies/back-ends/opensshserver.config takes precedence. From my ...
pepoluan's user avatar
  • 1,363
0 votes
1 answer
61 views

sudo passwordless in ssh session not working

In RHEL7, I have the same local users on all machines within my cloud tenancy. That local user is configured in sudoers to be able to: run all commands, run sudo commands without password EDIT: ssh ...
Lou Lee's user avatar
0 votes
1 answer
82 views

"Connection refused lost connection" error while using scp command

I tried to transfer a file from an HPC system to a remote CentOS system using the following command line: scp /ANKAN/data/abc.pdf [email protected]:/data/ANKAN But I am getting the following ...
Ankan Sarkar's user avatar
1 vote
1 answer
2k views

How to upgrade OpenSSH on Debian 12?

On Debian 12 (the latest available Debian distrib at OVH), I'd like to upgrade OpenSSH. # ssh -V OpenSSH_9.2p1 Debian-2+deb12u2, OpenSSL 3.0.11 19 Sep 2023 So the installed version is 9.2. For PCI ...
thierryler's user avatar
-1 votes
3 answers
203 views

What openssh version is best on Linux when it comes to stability and security ( sftp security )? [closed]

I work in a government agency. We are running a sftp client and sftp-server on a DMZ system where we receive and send files over the internet. Our environment: OpenSSH_7.4p1, OpenSSL 1.0.2k-fips 26 ...
Anders's user avatar
  • 3
0 votes
1 answer
43 views

I am still required to enter both passphrase for the key and server password when using SSH key authentification

I am trying to setup remote access from my new laptop (client) to my old laptop (server). The old one runs on Linux Mint 21.2, the new one on Ubuntu 23.10.1. I created a pair of SSH keys on the client,...
Daigaku no Baku's user avatar
0 votes
1 answer
433 views

SSH Unable to negotiate: no matching host key type found

I have an issue where older clients aren't able to connect to current (v8.x) versions of openssh server. I'm familiar with adding ssh-rsa,ssh-dss to the list of available key types but that doesn't ...
Honkypants's user avatar
0 votes
1 answer
50 views

How to use the scp command on two different servers without a password prompt?

I am trying to transfer files from one server to another using the scp command without having to enter a password. To this end I generated key files and copied them to each server's .ssh folder; but ...
Jay's user avatar
  • 1
1 vote
0 answers
931 views

SSH StrictHostKeyChecking non-interactive

Since v9 of OpenSSH StrictHostKeyChecking is the (IMHO sensible) default. This makes that when the host key changes SSH refuses to connect until the host key in the ~/.ssh/known_hosts file is changed. ...
bakunin's user avatar
  • 531
0 votes
1 answer
84 views

Unable to SSH Login using kerberos

Setup I have some basic KDC setup at kerberos.domain.intranet (This is in my own Intranet DNS) I have another machine at xux.domain.intranet (This being the target machine to which SSH) I setup the ...
Delfin's user avatar
  • 150
0 votes
0 answers
124 views

SSH from OpenSSH 9 to OpenSSH 5 protocol 2 fails: “illegal argument”

I'm trying to connect from a VMware ESXi 8 machine to a VMware ESXi 5 machine to transfer all the virtual machines.  The problem is that ssh doesn't connect.  The old machine has OpenSSH 5 and the new ...
Miguel's user avatar
  • 109
-2 votes
2 answers
116 views

locked out of my server Permission denied (publickey)

I was connected to my server. i edited the /root/.ssh/authorized_keys and added ----BEGIN RSA PRIVATE KEY-----at the start of the public key and -----END RSA PRIVATE KEY-----at the end of the public ...
Huzaifa Malik's user avatar
0 votes
0 answers
70 views

OpenSSH Requires Password AND Public Key

I've inherited an old CentOS-6 system with OpenSSH 5.3 installed. And OpenSSH is behaving oddly: Currently the daemon requires the use of a public key and a password in order to login. (It's been this ...
Eric Pretorious's user avatar
0 votes
1 answer
232 views

How to get rid of ssh bandwidth limit?

I was playing around with a server I set up myself, running archlinux, and when I tried to retrieve files from it, using scp or rsync, I noticed the download speed was abnormally low, being capped at ...
Mayeul Lnr's user avatar
0 votes
0 answers
31 views

Local port forwarding using SSH only works from some machines

I am setting up an SSH server on Ubuntu 18.04.6 LTS. I am trying to use the server for remotely accessing Jupyter Notebook. For that purpose, I have downloaded an opens-server package. I set up ...
altair08's user avatar
0 votes
2 answers
535 views

Issue with SSH Client Alive Interval in sshd_config

We are currently using SSH for our project, and we need to implement a feature where SSH users are logged off after 1 minute of inactivity. Below are excerpts from our ssh_config and sshd_config files:...
karkator's user avatar
0 votes
2 answers
111 views

Fedora SSH client sends RST after 3-way-handshake

I have a client running Fedora 38 and OpenSSH_9.0p1, OpenSSL 3.0.9 30 May 2023. The server is an old Buffalo NAS running Debian 11.8 Bulleye, it has OpenSSH_8.4p1 Debian-5+deb11u3 and OpenSSL 1.1.1w ...
Marcel Boldt's user avatar
6 votes
6 answers
10k views

How to disable ChaCha20-Poly1305 encryption to stop the terrapin ssh attack

How to disable ChaCha20-Poly1305 encryption from ssh under Debian? I tried (as root): echo 'Ciphers [email protected]' > /etc/ssh/sshd_config.d/anti-terrapin-attack echo 'Ciphers -...
xpt's user avatar
  • 1,644
0 votes
0 answers
34 views

Error encountered when trying to login on remote system [duplicate]

When trying to log on remote system using ssh, I encounter the following error : Unable to negotiate with 172.15.239.54 port 22: no matching host key type found. Their offer: ssh-rsa,ssh-dss How do I ...
Rails metasphloit's user avatar
6 votes
2 answers
13k views

How do you mitigate the Terrapin SSH attack?

The Terrapin Attack on SSH details a "prefix truncation attack targeting the SSH protocol. More precisely, Terrapin breaks the integrity of SSH's secure channel. By carefully adjusting the ...
KJ7LNW's user avatar
  • 495
0 votes
1 answer
328 views

sFTP admin permission denied when placing files into user directory

I am running Ubuntu 22.04.3 with an sFTP server configured through SSHD. I have several user home directories each with a dropoff and a pickup folder inside of them. While my admin user is able to ...
Vince D's user avatar
0 votes
0 answers
53 views

OpenSSH Connection Timed Out Issue

I am using Linux CentOS8 distribution. Openssh 8.0 installed on this server. When I try to connect via SSH to this server, connection timed out happens. I got a tcpdump and tcpdump shows that SSH ...
Mr.Peace's user avatar
0 votes
1 answer
69 views

Why are 3 entries added to ~/.ssh/known_hosts even though I use only a single key type?

I set up a new server (hostname: odroid) and copied my public ed25519 key to it. I signed to it for the first time and noticed 3 new entires have been added to ~/.ssh/known_hosts on my local machine: ...
Bartek Pacia's user avatar
-1 votes
1 answer
282 views

Why can't I scp a file to this host while I can ssh to it?

I configured sshd on my remote host with /etc/ssh/sshd_config.d/custom.conf: AddressFamily inet6 PermitRootLogin yes PubkeyAuthentication no Match Address fe80::d075:6982:4410:e071 This is a fresh ...
John Smith's user avatar
0 votes
1 answer
158 views

How to authenticate through OpenSSH then sudo with only one Ticket Service (Kerberos TGS host/fqdn)

By now, we are using OpenSSH GSSAPI authentication on all of our servers (Debian from 10 to 12). Then we sudo -i, using ldap authentication (through sssd-ldap). I would like to get rid of the ldap ...
neophenx's user avatar
0 votes
1 answer
156 views

Setting up a SSH Lab using docker on my local machine

I am using docker ubuntu container to set up an SSH lab on my local machine. I have interactively started the container and installed open ssh on it with other tools. I ensured that I port forward ...
sourabh dhingra's user avatar
0 votes
0 answers
60 views

How do I configure OpenSSH to not use the "-sk" versions of keys for hardware authenticators?

I have a system that needs to connect to several clients through SSH keys. This is in a somewhat legacy environment, and clients have varying OS and SSH versions. I created a new ed25519 host key on ...
jstarek's user avatar
  • 1,724
0 votes
1 answer
135 views

Log in to remote server by using a generated public key

I have a zsh script with which I logged into a remote host to copy some folders. The system asks me each time to give the password of the local host which I want to bypass, otherwise I have to enter ...
ecjb's user avatar
  • 445
0 votes
0 answers
224 views

SSH Keys Not Recognized?

I have two Debian (11 and 12) systems. I'm trying to verify ssh access from server A to server B via keys, following this video https://www.youtube.com/watch?v=vINn1MIrf7o. I try to use the keys, ...
Rez's user avatar
  • 1
0 votes
0 answers
261 views

key type ecdsa-sha2-nistp521 not in PubkeyAcceptedAlgorithms [preauth]

I have trouble setting passwordless authentication on a host: Sep 21 09:57:36 pvestorage2 sshd[1688625]: userauth_pubkey: key type ecdsa-sha2-nistp521 not in PubkeyAcceptedAlgorithms [preauth] OS: ...
Vatharian's user avatar
0 votes
0 answers
70 views

What are the OpenSSH ciphers default rekey transmission limit values?

The OpenSSH sshd_config man page says for RekeyLimits first argument: Specifies the maximum amount of data that may be transmitted before the session key is renegotiated [...] The default is between ‘...
user avatar
1 vote
2 answers
161 views

Can two linux users share .ssh folder keys to connect to an SSH server

I have two linux users user1 - regular account with auth key stored in /home/user1/.ssh/ user2 - service account without home directory How can user2 access user1's keys to connect to the remote ...
try.aaam's user avatar
1 vote
1 answer
8k views

CentOS 7 upgrade openssh to 9.3p2

I am asked for an upgrade OpenSSH version because of CVE-2023-38408, here is my process.: yum groupinstall -y "Development Tools" yum install -y zlib-devel openssl-devel wget cp /etc/ssh/...
Chan's user avatar
  • 111
0 votes
0 answers
186 views

ssh-copy-id closed by remote host

I'm trying to copy public ssh with ssh-copy-id but it gives a connection close: user@serverA:~/ctm/cm/AFT/data/Keys$ ssh-copy-id -p 1222 -i /home/user/keys/serverA.pub vivek@serverB /usr/bin/ssh-copy-...
defekas17's user avatar
2 votes
1 answer
2k views

Are all Debian 11 systems automatically vulnerable to CVE-2023-38408?

I really really hope I'm wrong here, but it seems that Debian 11 has a vulnerable version of OpenSSH. My OpenSSH banner reports my OpenSSH version is: 8.4p1 Debian 5+deb11u1 I checked with sshd and it ...
Sir Muffington's user avatar
-1 votes
1 answer
61 views

Why does ls show this file twice with different sizes?

Why is 50-redhat.conf listed twice with different file sizes for this directory with this ls: ls -la /etc/ssh/ssh* -rw-r--r--. 1 root root 1921 Aug 2 02:58 /etc/ssh/ssh_config -rw-------. 1 ...
iletras's user avatar
  • 442
0 votes
0 answers
50 views

SSH not working outside of local machine

So, I'm trying to learn SSH. I don't have a public IPv4 address. So, I'm using my IPv6 address but SSH is only working inside my local machine. When I try it with WSL, it is showing ssh: connect to ...
lunix's user avatar
  • 129
0 votes
0 answers
39 views

Cannot login into SSH from non-admin account. /bin/bash: No such file or directory [duplicate]

Although I have found many other posts on this exact problem, none of their presented solutions have fixed my issue. I have configured and SFTP and SSH server on my raspberry pi. And ever since I ...
Kuba0040's user avatar
0 votes
0 answers
70 views

Incorrect MAC error while using ssh from windows to linux

I am trying to ssh from a windows system to an azure centos vm. But I am getting error incorrect MAC ... On further checking i identified it only happens when the mac algorithm used is umac-128-etm@...
Zez s Shin's user avatar
0 votes
2 answers
104 views

How can I map the sshd logs to my current ssh session?

I am exploring methods to correlate my current SSH session with the SSHD logs. I aim to extract specific information from the SSHD logs that pertain to my SSH session only. Jul 04 09:39:06 linuxbox ...
Karthick's user avatar
  • 123
1 vote
0 answers
123 views

Conditionally skip ssh-config options when ssh is too old for them?

How can I use SetEnv in ~/.ssh/config (and the same config on various systems), but not throw an error when ssh is too old to support it? I've tried adding a Match exec statement to exclude that ...
Jacktose's user avatar
  • 441
0 votes
0 answers
439 views

What is the difference between a Match all and a Host * block in ssh_config

As I was reviewing my current OpenSSH client configuration file and intensively reading the ssh_config(5) man page, I found that, from my understanding, both Match all and Host * will achieve the same ...
Étienne's user avatar
3 votes
1 answer
375 views

Does ssh client interfere with named pipes? [duplicate]

Setup: I have a system in bash where I have a single file that spawns off a pipeline of background processes. In stage one of the pipeline, there are multiple processes writing to a single named pipe. ...
Fury's user avatar
  • 33
-3 votes
1 answer
222 views

Use openssh for ssh connections and for public sftp

I have a system to which some users need to connect trough regular SSH. I will name them the “Privileged Users”. In the same time this system should provide an SFTP server to “Anonymous” user (without ...
fauve's user avatar
  • 1,278
0 votes
1 answer
372 views

How to make a script to forward commands to an SSH server?

I have a remote SSH server with several custom utilities for my work. However, there are times when I feel lazy and don't want to start a full SSH session just to execute a single command. This ...
JM0's user avatar
  • 221
3 votes
0 answers
579 views

Very odd SSH known_hosts verification failure with certificates

I recently upgraded one of my machines to latest Ubuntu 22.04, and now I am experiencing a very strange SSH server verification issue. Here is a short explanation of the situation. I am using SSH ...
Teemu Karimerto's user avatar

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