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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How roaming works with ssh private keys?

This occurred to me when looking at the security model wireguard is using. Instead of relying on users credentials and Radius authenticating central server each user has a private key used to ...
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Hydra attack ssh : The message is successful, but when using the errors

I execute the command hydra -l ubnt -p ubnt 138.255.252.193 -t 4 ssh I get the message it's successful Hydra (http://www.thc.org/thc-hydra) starting at 2021-02-22 11:32:05 [DATA] max 1 task per 1 ...
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How to reach the port 80 from a pivot machine

I have this lab setup: kali (192.168.1.81) => Windows 10 (10.10.10.130) => Metasploitable (10.10.10.149) I hacked Windows 10 first, then I make a pivot via SSF tools: ssf.exe -g -F 22222 -L 10....
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ssh into a server with knowledge of ca bundle

Let's say I had a ca bundle with many certificates in it on my server. I accidentally gave this to a team of programmers I have hired. Could they theoretically use this to somehow ssh into my server ...
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is there a way to close 22 ssh port from public, ubuntu?

I am using putty and private key to access my development server. I used Nmap online port scanner, to see which ports are visible to the public, and in fact, the 22 is open. My question is, is it ...
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When I provision (sign) keys to end-users, can I force the definition of certificate expiration (different from CA expiration)?

Before I proceed to testing this myself I wanted some clarity. I have a basic understanding of SSH and Cryptography but not completely sure about this plan. I want to implement a key rotation policy ...
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Can you bruteforce a SSH password without alerting the server owner?

What happened? This is a live event that a friend of mine is working on, a company's systems were breached by a Threat Actor (TA), when the Cyber Sec company was called in and tried to regain access ...
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How to prevent SSH host impersonation attacks?

I have an SSH server, where users can login to with their username and password. I want to prevent attacks that try to steal the user's passwords. Is there a way to prevent an impersonation attack on ...
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VPS host shows plain text “root” account password upon reinstall of unmanaged VM

I recently started using a VPS hosting service, that offers unmanaged VPS. It allows me to reinstall the VM at any point in time, choosing from a number of OS ISO files (doesn't have to be the same OS ...
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ssh and anonymity?

According to the man page, ssh by default sends multiple public keys from files in the ~/.ssh folder, one by one, until authentication success. Does that mean that the server side could know multiple (...
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How hacker/ others get your SSH private key / stole your SSH private key?

I know we must keep private keys secure, but as long as we don't share the private key, what can go wrong? How hackers/others can steal/get your private key? What is the possible way that can happen ...
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Are AWS EC2 key-pairs compromised when an EC2 instance is compromised?

Suppose I have multiple EC2 instances deployed with the same key-pair. The key-pair is used for SSH access and general troubleshooting. If one instance is compromised, do I need to be concerned about ...
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Brute force ssh login attempt on AWS t2.micro

I have some confusion in understanding the security groups itself i guess. The login attempts are being made to different ports , here are the logs Jan 08 00:00:13 ip-172-31-10-252 sshd[6067]: ...
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Efficiently handling malicious, single connection attempts to a server?

I wanted to know what efficient way is there to handle malicious attempts to connect to my server by single IPs. The attempts show up logged in /var/log/auth.log as Connection closed by IPaddress port ...
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SSH in AWS vs SSH on GitHub [closed]

This is not much of a technical but more of a practical question. Both in AWS-EC2 instance and GitHub repos I had to generate a cryptographic key pair to encrypt data sent over SSH tunnel. For AWS the ...
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Logging into remote server via SSH using VPN (Wireguard). Is it foolproof?

I have a remote server into which I login via ssh. On this server I have setup a Wireguard VPN to which my host connects. The ssh server (ssh daemon) listens on a private IP interface (the server's ...
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expose home applications to the internet

I have some web applications (for example jupyter notebook) running on my home pc (ubuntu) that sometimes I would like to access remotely. What would be an efficient and safe method to do it? I don't ...
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How to create same ssh key pair on different systesm at different times

Was going through the SSH key pair generation and did tried with the few systems i have. refer to the below command and the thumbprint value post key pair generation. $ ssh-keygen.exe -t rsa ...
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Securely Connect Employee PC to Business Private Network

I've recently become the "tech guy" at a startup, and am tasked with standardizing our hardware infrastructure. Further more, I choose how employees working from home will connect to ...
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can I trust the output of `ssh-keyscan localhost`?

I am aware that running ssh-keyscan on a remote host doesn't prove that the remote host is indeed the one you are trying to connect to, only that it's the same one each time, but what about if I run ...
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socks5 nmap scan [duplicate]

Does nmap support the following (-sS -sV -sC -O ) with a scan using socks5 proxy and if it is not what is the best way to scan linux system through a windows system ?
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Different SHA256 checksum of same version of ssh binary on different machines

I was wondering if I compare SHA-256 of two binaries with same version on different machines, results will be two identical checksums. I tried this on ssh on macOS (Catalina). (I checked that ssh -V ...
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Why can SSH negotiatie two different encryption and authentication algorithms?

I recently found out, that according to the RFC, SSH can negotiate two different cipher (and MAC) algorithms for server-to-client-encryption and for client-to-server-encryption (check section 7.1. for ...
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Host Keys in Public/Private Key Auth

I've chased my tail into a late night circle thinking about public key authentication to cloud instances. As such, I have some questions on the function of host keys when authenticating an SSH session....
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Can/should I automatically report network break-in attempts?

For the last 15 years I've been using SpamCop to report the spam I receive. I do this because it sometimes results in spammers and the third-party machines they compromise getting shut down, at ...
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if computer is compromised, does hardware key still protect in ssh?

Let's say I sign into my local pc with a hardware key (eg yubicon). Let's say I further sign into a sensitive server (as root) via ssh using yubicon hardware key as well (ie only way to get into ...
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What is the -sk ending for ssh key types?

ssh-keygen has the following options for a key type (-t): dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa I am not familiar with the -sk notation and it's not explained in the man page. What does ...
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133 views

How does john the ripper crack hashes using wordlists?

How does John The Ripper work when trying to crack passphrase of a private ssh key? As in what steps are involved when it tries to do so? What's the role of ssh2john in the whole process?
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Ongoing blacklisting by firewall SSH connections when SSH is blocked

I've recently discovered a massive DDoS attack from mostly Asian IP addresses on one of the company's routers. Even though the router is set up to drop all the packets not coming from LAN and the ssh ...
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Is SSH server secure from internet access outside private network?

I have a desktop computer in my home network with SSH server running on it. Using another computer in my private and local network (class C IP addresses: e.g., 192.168.0.2, etc) I sometimes use SSH to ...
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How do I connect using ssh tunnel to heroku's cleardb mysql database from some gui tools like mysql workbench or beekeeper studio, when run on ubuntu

Im currently trying to connect to the Heroku's mysql cleardb database from beekeeper studio. My connection works when done normally. But when I use the ssh tunnel Im facing some issue. Their ...
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Is accessing Cockpit through SSH tunnel secure?

I can't find a definite answer on accessing cockpit from outside machines securely. Just allowing it through the firewall like that doesn't seem safe. It only uses basic user and password ...
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OpenSSH artifacts, remote system access? [duplicate]

After stumbling upon some unknown folders in my unused OneDrive (posted question), I did some digging arround and found some interesting logs. Apparently, OpenSSH had been used for remote access on my ...
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Storing Private Key Files on Android 10 as a User

Say I have a private key as a user of an existing application for SSH, password management, etc. As far as I know if it is in shared storage, any application with storage permissions can access it. If ...
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SSH certificates and mutual authentication

SSH certificates are a recent addition to the protocol, and I see them as being used mostly for the clients. Can the server use an SSH certificate too? And if so, is it possible to have mutual SSH ...
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134 views

Recommendations on minimal alternatives to openssh [closed]

Although openssh is awesome, I'm interested in exploring some more lightweight FLOSS alternatives to use for connecting to servers I'm administrating (and using alone). Since I only need a minimal ...
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170 views

Is it a good idea to host a SFTP server within a dockerized environment with mounted host directories?

For platform hardware independence, a proposal to host a SFTP server within a containerized environment was being considered. A container or pod would have the server running within it, with mounted ...
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MITM attack on key based ssh connection when knowing server's private host key [duplicate]

I read this article that claims that ssh mitm are not possbile when private / public keys are used: https://www.gremwell.com/ssh-mitm-public-key-authentication I wonder how this would change if an ...
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How does the weakness of SHA-1 introduce attack vectors in SSH?

The security branch of my company worries that the use of older versions of OpenSSH (pre-7.4), where the only Key Exchange Algorithm available is SHA-1 is a major security issue. They suggest ...
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Why do syn scans not work over proxy set up through SSH's dynamic port forwarding?

I have set up dynamic port forwarding using SSH. Although nmap scans over proxychains return accurate results, a SYN scan does not.
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Why does the server generate a random challenge for SSH authentication?

Wouldn't it be more efficient if the client initiated the connection by generating their own message, and encrypting it using their private key, then sending both messages to the server so it would ...
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Are hardware security keys (e.g ones supporting Fido2) “able to protect authentication” even in case of compromised hosts?

Correct me if I am wrong, please. I understand that 2FA (MFA) increases account security in case an attacker obtains a password which might be possible via various ways, e.g. phishing, database breach,...
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Backing-up to an untrusted cloud

Not sure if this kind of review/validation question is allowed - please delete if it isn't. Like many before, I'm looking for ways to do cloud backup in a way where I trust that I'm still the only one ...
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124 views

Is SSH using TLS?

I have an odd case where a vulnerability scan is reporting that sshd is vulnerable because of TLS. I didn't think SSH used TLS, so can someone help me explain why "openssl s_client -connect ...
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191 views

Security risks from exposing ssh to a home server

I'm not sure if this is the right place to ask. My goal is to establish an external connection to my home server through ssh and tunnel some ports to the laptop. For this reason, I've exposed the SSH ...
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How to stop outgoing SSH on port 443

Let us say that a small company has an internal network for employees. All employees are granted Internet access via a NAT device (not a proxy) and perimeter firewall only allows outgoing connections ...
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What prevents someone from spoofing their public key when trying to establish an SSH connection? [duplicate]

Recently I've been trying to learn the mechanisms behind SSH keys but I came across this question that I haven't been able to find an answer to (I haven't figured out how to word my question such that ...
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Mutli user/mutli service authentication + HSM as a key signing/encrypting key?

I'm looking to implement a multi user authentication environment for a small (11) but growing team, to a reasonable number (currently 500+) of managed devices/services (routers, firewalls, linux cloud ...
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95 views

How is VPN tunneling actually implemented? [duplicate]

I am new to VPNs, have used them a few times, have read about "how they work" (which is all very high level), and am now confused about how this is actually implemented (so I can come full ...
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Should you let yourself ssh into every machine in your network?

I am wondering how you should setup your network (AWS) so you can debug different things that might occur. Obviously there's logging, but it seems at some point you might require SSHing into the ...

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