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 does SSH protocol encrypt the data in transit when using user and password for credentials? [closed]

From my understanding, the SSH protocol encrypts everything that is sent over channel and this is why it is secure. My question is for setup when authentication is done using username and password. My ...
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Is getting server host key with ssh-keyscan secure?

I am trying to establish SSH connection to a server through a program. As a pre-requisite to be able to do so, I am getting the publicly available server host key using ssh-keyscan <hostname> ...
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Is it fine to save contact information on a ssh sever and is it secure?

My mom wants to find a way to store information securely and host it remotely and wants to host our own mini-server on a Raspberry Pi that'll have contact information of the customers. My sister said ...
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How exactly is RSA used in SSH [duplicate]

I can find oodles of websites that tell me the server retains the public key and the client retains the private key. But nothing on how the client authenticates to the server and - perhaps - how the ...
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Why are SSH MITM tools able to read and modify data?

At my university, we are learning how to use SSH for server administration. We learned that SSH is secure, but there are some tools that allow man-in-the-middle attacks on SSH. How can such tools ...
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Should I backup a GPG key used for Authentication?

Regarding backups (escrows) of GPG (OpenPGP compliant) keys, I seem to understand that (E)ncryption keys need to be backed up, to prevent data loss, and that (S)igning keys should not be backed up, ...
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How can you attack or redirect the client from the server over an RDP or SSH conneciton? [closed]

I have a penetration testing scenario where I am on the network with two machines, Machine A and Machine B. I have complete control over Machine B and am trying to leverage that to get access to ...
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Preventing MITM for a new SSH daemon

Supposed I have a number of HTTPS servers on different networks, would it be safe enough to use them together to verify a new SSH daemon's public key? i.e. if they all return the same fingerprint, is ...
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Serverside SSH security best practices

In light of the 2006 Debian OpenSSL fiasco, it seems prudent to take additional precautions as part of a "defense in depth" strategy against future possible vendorside-introduced ssh ...
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IPSec MTU DDos attack

I have this configuration: HOST-A <---> GAT-A <---> MiTM <---> GAT-B <---> HOST-B I'm doing a security project on MTU-IPsec vulnerabilities and following this guide of Hal-...
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SSH and PCI on Insecure, Dirty Side

Does current PCI code require SSH connections be restricted to enumerated (specific) client IP addresses on the unsecure, dirty side? Isn't that outside the scope of the PCI code?
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ssh login attempts still showing up even with password login disabled? [duplicate]

I switched all my servers to ssh publickey login and disabled password login about a week ago (root login IS still enabled). I also run Fail2ban and logwatch. Why is there still login attempts ...
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SSH reverse tunnels: can the intermediate server eavesdrop on an SSH session?

Suppose there are three computers: (1) my laptop, (2) a server that has a public static IP address, and (3) a Raspberry Pi behind a NAT. I connect from (1) to (3) via (2) as explained below. On the ...
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Why should we only keep the private key secret, why not the public key? [duplicate]

If I am not wrong, both private key and public key are the same since communication is possible only if both keys are matching. So, why we should only keep the private key secret, why not public key? ...
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SSH Public Key Authentication Strength Port 22 [duplicate]

Let’s say I have a server with Port 22 opened to the internet , password authentication disabled, and root remote login disabled. Only Key Authentication is enabled. If the key is tightly secured, is ...
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How to make access to a remote program without that the user has the possibility to run any Linux command?

I have an interactive program. Actually, the program can be reachable over SSH. In the .profile file, the program is launched immediately and with the interactive interface it is not possible to ...
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In an enterprise environment, should developers/maintainers be able to look at production logs by accessing the application servers?

I came across this practice, from a big company handling personal customer data, of not allowing developers/maintainers to look straight at the application logs (e.g. good old tail | grep) by ...
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What is the added security of “PermitRootLogin no” alone?

Referring to this Q&A: The setting PermitRootLogin no alone does not prevent su - after logging in as a normal user. As described in the referenced answer, there it is possible to prevent su with ...
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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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782 views

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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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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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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