Questions tagged [ssh]
SSH (Secure shell) is a protocol for secure communication between computers to execute remote commands, transfer data and tunnel TCP connections.
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End-to-End Multihop ssh connections through chained sessions/connections
I'm interested in forwarding opportunities of ssh (openssh), more precisely something like nested connections.
As far as I understood the best way to use multihop ssh is chained tunnel, but in the ...
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Are the sha1 hashes used by common ssh configurations insecure?
I got an automated PCI security test result that checked various server configurations. The automated test determined the server to be unsafe due to the use of sha1 algorithm in some elements of the ...
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2answers
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Is PuttyGen secure?
I'm using PuttyGen to generate ssh keys for various windows computers. It requires a lot of manual user input, specifically in the form of swirling the mouse around in the window pane. I understand ...
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1answer
62 views
Is there any harm to writing a short plain-text string to authorized_keys?
I have a CFN template where I'm seeding an authorized key for testing via paramaters, through a build server. If this value is not provided by the build job, it defaults to a short, plain text string, ...
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Why does Cain and Abel downgrade SSH version 2 to v 1.51?
I am developing a lab exercise with Cain and Abel and want to know why it is necessary to downgrade SSH before attacking.
Identification phase
The server sends to the client an identification ...
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I think my ssh server is under attack and it's really trecherous [duplicate]
I'm new here so please bear with me. And thanks for the opportunity. This is an awesome resource.
For the past few days, my ssh server (it's a small convenience I run just so that I can access my ...
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1answer
71 views
Should I treat my SSH username like a secret?
I'm trying to automate the deployment of my blog.
Most CI providers are using virtual machines/Docker containers with Linux, so I'm learning about shell scripts and SSH now, which is all new to me.
...
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1answer
23 views
Providing access to Git repo behind a Firewall using Certs/Keys for Authentication
We have git repo sitting behind a firewall. As I see, there are two ways of authenticating/accessing the git repo
Add a Reverse HTTP Proxy in the DMZ that communicates with the git repo. This will ...
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1answer
44 views
Please may I know why I am getting this Sshd log
why I am getting this sshd log
Feb 1 13:07:57 sshd[6453]: Failed password for root from 193.34.22.63 port 28980
ssh2
Feb 1 13:08:26 sshd[6897]: Failed password for root from 91.205.189.15 port 48155
...
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2answers
76 views
Prey vs SSH for remote wipe of stolen laptop under Ubuntu
I have to be able to wipe a stolen laptop remotely (contractual obligation), and the only product I found that supports that on Ubuntu is Prey Project. (Also appears in some other stack exchange ...
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1answer
88 views
Sending Private Keys, does it make sense?
There's some logic that I'm not following whenever my organization sets up VMs for SSH access. Perhaps someone can help me understand.
Our process is currently as follows
Generate Keypair on Linux ...
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3answers
9k views
Does a fake SSH server have any purpose security-wise?
I stumbled upon this sshesame software which appears to imitate an SSH server accepting any username/password, only instead of executing the subsequent shell commands it logs them in a file.
What I ...
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SIEM: Correlating remote logons to associate origin and target user
How is it possible to correlate or detect user logons eg via ssh/rdp to associate the origin user and target user.
My use case is to know who actually (personal/identifiable) used a technical account ...
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1answer
34 views
Is it safe to browse the web through an SSH SOCKS5 connection to an untrusted proxy?
I have established an SSH tunnel to an untrusted machine:
ssh -N -D 12345 john@example.com
Next, I set up Firefox's connection settings to use the SSH tunnel by setting the SOCKS host to 127.0.0.1, ...
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1answer
74 views
How do these attackers find my IP? [duplicate]
Recently, I have been reading a lot of my ubuntu log files (in /var/log/auth.log), and I can see that some IP addresses are actually trying to 'brute-force' their ways into my VM using SSH by testing ...
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1answer
55 views
Use GPG smartcard and gpg-agent to protect multiple SSH keys
I have a Yubikey acting as a GPG smartcard. SSH is configured to use the smart card socket for authentication, and authenticating with the GPG key with Authentication capabilities work fine.
ssh-add -...
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SSH-1 key length
What is the maximum size in bits of one SSH-1 key? 4096?
I found some docs where this value is listed and others without limit
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1answer
101 views
Techniques used by highly sophisticated entities to snoop on VPN or SSH traffic?
It is mentioned in almost every where that very strong agencies, and governments are able to watch the online activity of the people. Aside from techniques like attacking computer networks, and ...
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1answer
88 views
Risk involved with using SSH for CTF challenges? [duplicate]
I'm new to the INFOSEC scene and was intrigued by the concept of CTF challenges. I was hoping to get started with OverTheWire.org which requires you to SSH to their server to complete the challenges.
...
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1answer
64 views
Why can I use 2 different private keys to connect to my SSH server storing only 1 public key?
On my server ~/.ssh/authorized_keys contains only 1 public key. However, I can connect to it using 2 different private keys.
One private key looks like this:
-----BEGIN RSA PRIVATE KEY-----
...
45
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2answers
7k views
How can SSH server know private key is incorrect if passphrase havent been provided yet?
I have server which I am accessing via SSH. I only allow the authentication to be made with private key. Normally when I login via PuTTY, I am first asked for username and then asked for passphrase ...
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1answer
95 views
How do I determine if an existing SSH private key is secure?
For an ordinary user, how would I verify that a private key file was generated using reasonably secure algorithms? In response to things like allegedly insecure ssh-keygen defaults.
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1answer
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What are the best ciphers in terms of performance for SSH tunnel?
From a security standpoint, there are few good cipher options to use with SSH, such as ChaCha20, AES 128/256 GCM/CTR. As I understand (please correct me if I wrong), all of these offer pretty strong ...
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3answers
4k views
Is ssh with public key authentication, no passwords secure enough?
I have a web server set up and would like to connect to it from outside using Tor.
The web server simply serves up a simple webpage that will act as an interface for a program running on the machine.
...
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5answers
234 views
Difference between SSH Tunnel / Proxy and VPN in terms of security
What benefits does a VPN have over just using a regular SSH Tunnel?
I'm considering setting up OpenVPN on a server, but was wondering what benefits that would have over just using that same server as ...
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1answer
129 views
If my private key is password protected, then how is it used without asking me for it?
Relating to TLS and SSH. If my private key is password / passphrase protected, how is this then used automatically during TLS or SSH communication without asking me for the password?
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Using the same private key for both WSL-Ansible and Putty (or WSL-OpenSSH for that matter)
I use Windows 10 home on my PC and SSHing to up to 5 Linux IaaS machines with either Debian/ArchLinux as server environments.
I use Ansible to orchestrate and continuously integrate and continuously ...
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1answer
49 views
How does the public key get authenticated during an ssh session
When using SSH, my private key is stored on my computer safely and my public key is given to the other party I wish to communicate with.
I understand that the two keys are mathematically related, and ...
0
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1answer
25 views
Is it worthwhile to restrict SSH on home web server to local network? [duplicate]
First, some background: I have a web server (Linux) which I run from my house. I have a relatively small website, and have just set up SSH. While modifying the firewall, I had the choice to pick ...
2
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1answer
58 views
Looking for SSH key management tricks that apply to a large fleet of machines to reduce the 'trust of first use' attack surface?
If you have too many machines and you are nearly always asked about a host key when you connect, it leaves an opening that the first time you connect to a machine it's a security threat, but anytime ...
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1answer
80 views
Why are passphrases protecting GPG / SSH private keys needed? [duplicate]
SSH and GPG each ask for passphrases during key generation. GPG also (at least from my experience) displays warnings if one is not provided and asks for confirmation that no security is indeed ...
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2answers
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Possible to get sshd (openssh) to log the public key of failed key based login attempts?
As I understand sshd (openssh in my case) typically does/may log the fingerprint/hash of the public key of incoming connections which are attempting to authenticate via key.
What I'm looking for is ...
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1answer
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I think my raspberry was hacked, what should I do? [duplicate]
First of all, sorry if all of this seems a bit stupid, but my field of expertise is software development, not security. So, here is what happened.
1/ The breach
I did something I really shouldn't ...
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0answers
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Malware abusing SSH agent active keys
I am thinking about this lately a lot, so I wanted to get someone else's opinion.
Let's say that I have an SSH key agent (e.g. Pageant or ssh-agent) running in background with loaded keys (keys were, ...
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2answers
117 views
How safe is it to allow key-based SSH access within LAN?
So this is my setup:
We have a few machines in a LAN, used for computation, which me and my colleagues access from the outside with SSH.
All our accounts on the LAN machines are managed and shared ...
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1answer
85 views
When first connecting via SSH to my server, the reported fingerprint does not match that given to me when I generated the SSH key
When I used ssh-genkey on macOS to generate the pair of key files (one named with .pub), that tool reported a SHA256 hash as a public key fingerprint.
When first connecting to my server, a Digital ...
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2answers
51 views
Capture Response Attempting to Connect to Open SSH
I want to be able to attempt to connect to a host using password authentication and store the server's response in a variable. This is to see what hosts in my list accept passwords for their ssh ...
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1answer
111 views
Secure SSH host keys
I am trying to fix my SSH setup on Fedora and RedHat with ssh-audit.
I managed to fix the ciphers and algorithms by setting
KexAlgorithms diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,...
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1answer
49 views
SSH: Best practice for PublicKey Authentication from multiple Devices
I have a Server I want to access via ED2559 PublicKey Authentication. How would one do it so it is as safe as possible from multiple devices? Should I add multiple PublicKeys to my Server or should I ...
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1answer
904 views
How did a bug like CVE-2018-10933 (libssh authentication bypass) happen?
How did a bug like the recent libssh vulnerability come to exist? Exactly what is the nature and root cause of the bug?
From libssh's website:
libssh versions 0.6 and above have an authentication ...
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3answers
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CVE-2018-10933 - Bypass SSH Authentication - libssh vulnerability
Looks like CVE-2018-10933 was just released today and you can find a summary here from libssh here
Summary:
libssh versions 0.6 and above have an authentication bypass vulnerability in the server ...
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1answer
186 views
SSH over VPN blocked on certain networks
Why can I only access protected resources over VPN on some networks?
Location | SSH to GitHub | SSH to private IP
------------------|---------------|-------------------
On-campus Wi-Fi | ...
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1answer
96 views
Honeypot SSH connection attempts with no interaction
I am seeing a lot (>50% of total events) of connection events on a honeypot I have set up but there is no further interaction, no brute force, just a connect then disconnect.
I'm thinking this is ...
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1answer
74 views
Why are SQL servers not attacked as frequently as ssh servers?
I have a server running with both SSH and MySQL accessible to the public internet. Both run on default ports (22 and 3306).
The ssh server is attacked by bots all the time. This is the output of ...
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0answers
54 views
Could a running SSH server somehow fool connected SSH client to create a reverse port forward?
Let's be extra paranoid and assume that the SSH server my client is connected to, was "enhanced" so that every SSH client that establishes an connection with it, will be tricked into thinking that it ...
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2answers
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End to end encryption in mobile banking? [closed]
Can we use E2EE to secure the communication between the bank and it's customers in the applications of mobile banking? And what is the status off E2EE vs SSH regarding this matter?
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Sending shutdown command via ssh using sudo non-interactively
With iOS 12 and the new Siri Shortcuts app, I've been thinking of ways I could leverage the SSH command capability in the app. For those of you who don't know, the app allows you to send a bash file ...
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2answers
147 views
Should I have an SSH bastion?
I am using AWS. I need to connect with a local SSH client to Linux EC2/ECS instances. I also need to connect with a local PostgreSQL client to RDS instances.
There are tutorials for creating SSH ...
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1answer
189 views
VPN vs SSH tunnelling for hotel wifi
I know it's recommended to use a VPN with a hotel WiFi but if I'm in a hurry and don't have time to setup my own VPN server would an SSH tunnel (invoked with ssh -D) work just as well to secure my web ...
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1answer
71 views
Access from external network safely to raspberry
I am implementing a home alarm system with raspberry and I need to access it from the external network. The initial idea was to use cascade VPN and ssh (in my university to connect to the cluster I ...
