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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Digital Ocean “Droplet” allgedly compromised for trivial, unpublicized website. Should I be worried abouty my own machine?

I got a message from D.O. about my Droplet saying they shut it down because there was a lot of outgoing traffic that looked like an attack. The site I had on that server was not very known at all. ...
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I want to roll my personal cloud hosted Password Manager using pass. How secure/insecure would this be?

I've come to the conclusion that I need to up my security. I currently have a dozen memorized passwords I use for every device and website. I'm against Keypass/Lastpass due to having to trust they ...
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141 views

Most secure SSH server [closed]

Which SSH server (compatible with Debian Wheezy) has the fewest (if any) exploitable security bugs?
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1k views

Use SSH config file with Putty [closed]

I'm using SourceTree (a Git GUI) which uses PuTTY as SSH client. I need to push some code into a repository for which I need to tunnel through SSH to do so. The trouble is, the repository and SSH ...
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261 views

SSH: benefits of using hashed known_hosts

What are the benefits of storing known_hosts in a hashed form? From what I read, it is supposed to protect the list of servers I am connecting to, presumably in a scenario where my account has been ...
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1answer
158 views

Python SSH vs SSL? [duplicate]

I read the What is the difference between SSL vs SSH? Which is more secure? , and it mentions there is the possibility they can be affected by similar attacks. Now that the heartbleed thing is out, ...
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1answer
208 views

Outbound Port 443 Open but Not Allowing SSH [closed]

My college wireless network has a firewall blocking all outbound ports except 443 and 80. The wired network, however, has none of these restrictions. I can connect to HTTPS sites (obviously). On my ...
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How are two systems able to set up a secure SSH tunnel over a public connection?

As I understand it, when two systems create a secure SSH tunnel, the first step involves communicating the 'guidelines' for the encryption of that tunnel. If an third system is able to listen in on ...
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4k views

How does SFTP function without a manually generated public/private key pair

I am learning about SSH and how to use it to secure file transfers and commands between a windows machine and a Linux server. Everything that I have read so far indicates that I need to use an SFTP ...
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Considerations when implementing a key based SSH-like auth scheme

I have a SMTP server where all the users (for an unrelated reason) will have public keys tied to their username and registered with the server. I want to add a non-standard extension that uses these ...
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1answer
158 views

Is it possible to use SSH agent for generic data encryption? [closed]

Is it possible to use running SSH agent to decrypt some data (supplied as a string or read from file)?
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515 views

How secure is OpenSSH on FreeBSD?

In a discussion about the recent OpenSSL information disclosure vulnerability, the subject of OpenSSH being vulnerable came up. While OpenSSH is not vulnerable due to the problem lying in the TLS ...
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434 views

Harden a server against mass SSH DoS attacks

How can a Linux server be protected against an attacker that tries to open a large number of SSH sessions (probably trying to brute force a password) that no ports remain to be able to legitimately ...
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308 views

My machine is hacked by someone and used to attack others via ssh, how to stop it? [duplicate]

I host my personal website on digitalocean. Nowadays, I received many abuse complaints which finally make them shutdown my machine. I feel really sad and angry. Someone complaints that my machine is ...
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4answers
3k views

Do I need to worry about my SSH keys if my system was vulnerable to Heartbleed?

So I'm getting conflicting information from members of my team. The premise is, if an attacker can keep requesting 64 kb chunks of memory from my server, they could get the entire memory footprint of ...
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1answer
450 views

Lots of failed outgoing sshd attempts. Am I hacked?

For the last two days I've been seeing lots of lines in my /var/log/auth.log that look like: sshd[xxxxx]: error: connect_to 0.gravatar.com port 80: failed sshd[xxxxx]: error: connect_to ...
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272 views

Server side SSH keys compromised

I'm interested in knowing what could be the consequence if the server side SSH keys of a host were compromised. The situation would be: An attacker manages to read the SSH private keys of the ...
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200 views

Is all RSA encryption now considered insecure? (Notably SSH and SSL)

Some of the leaks which emerged during/after Snowden concerned the fact that the NSA was paying the organization behind RSA a lot of money in order for them to systematically weaken the encryption by ...
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144 views

Best approach for restricting remote ssh session

Using the following files, I have attempted to restrict the SSH remote login. Having lack of knowledge in linux environment, I don't know the drawbacks and vulnerabilities between the following ways. ...
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2answers
71 views

How to setup cronjobs that do scp without saving the .pem file on either of the machines

I have the following situation and want to know what are the best practices to do such things without exposing myself to security issues I have two servers both use the same private key for login. ...
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1answer
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Open ports and SSH Tunneling to shared hosting

I know your time is valuable so I'm not waiting for specific answers to my situation. I don't mind reading documentation, so pointers to something that converges would be greatly appreciated. I don't ...
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0answers
95 views

Test S/KEY support for PCI compliance - CVE-2007-2243

In order for our business to be PCI compliant, we need to prove that we are not vulnerable to CVE-2007-2243. This states that: OpenSSH 4.6 and earlier, when ChallengeResponseAuthentication is ...
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2answers
466 views

SSH Security allowing only certain users to connect to the server [closed]

I have set up a remote ssh server on the cloud. I am newb at these things and have managed to bypass the required firewall using SSH. Now I plan on giving the access to only 2 more friends of mine so ...
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4answers
218 views

Are there Ciphers designed to be slow?

To safely store a passwords, it is better to store them hashed using a hashing function designed to be slow like bcrypt. The goal is to trump brute force attacks. Are there any ciphers slow enough to ...
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1answer
170 views

Secure installation of KVM VPS?

This question has also been asked on Server Fault, but was not taken seriously. I hope this is a better place for it I'm going to install Debian Wheezy on a KVM VPS. VNC access to console is enabled, ...
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309 views

How do I determine where ssh login attempts are coming from?

We had been testing an AWS instance accessing an internal Ubuntu 10.04.3 server, so had modified our firewall to allow all ports from that specific IP address to the server. We then released the AWS ...
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1answer
216 views

2-Factor Auth with SSH

I recently acquired a Synology NAS (DS1513+). I am looking to expose SSH access remotely and to that end would like to harden SSH as much as possible. Is 2 Factor auth possible and if so what are the ...
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94 views

Security Implications of a ssh proxy vs ssh tunnel via a box I don't own

In order to access my desktop or the hpc cluster at my university, I need to go though an intermediary server managed by the university. Currently I use the "netcat method" (ssh -W) to access the ...
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44 views

Does restarting an encrypted session increase security and deter attacks?

When a user initiates a SSH connection for example, keys are exchanged and a session is established with a new "passphrase" each time. If an attacker were to attempt to brute force this connection, ...
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Is mosh now recommended by the security experts? (2014)

Mosh has been around for a while now. Although it's claimed to be "a replacement for SSH" by its authors, mosh does actually depend on ssh to do the initial authentication, after which an instance of ...
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516 views

Convert RSA SSH public key file into x509 certificate

I have a RSA SSH public key which I have converted from a x509 certificate and I want to be able to convert the SSH key back into a x509 certificate to compare the values with the original ...
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Why are DSA keys referred to as DSS keys when used with SSH?

When I generate a DSA key with ssh-keygen -t dsa, the resulting public key will begin with ssh-dss. How come? Why not ssh-dsa?
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Should I publish my public SSH key with user@hostname at the end?

In ~/.ssh/id_rsa.pub my public key is stored as: ssh-rsa magicmagicmagicmagic...magicmagic username@hostname When publishing my public key, should I include the username@hostname bit? Can I ...
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ECDSA vs ECDH vs Ed25519 vs Curve25519

Among the ECC algorithms available in openSSH (ECDH, ECDSA, Ed25519, Curve25519), which offers the best level of security, and (ideally) why?
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Managing and storing lots of SSH keys in the cloud

I have a pool of cloud servers (~50) that need to talk to many other remote cloud servers (~4000) using SSH. Each remote server has its own SSH key, so we need a place to store all of these remote ...
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186 views

Building an VM with Vagrant and connecting with ssh+2FA to protect a bitcoin wallet?

I would like to try to build a Virtualbox image to use with Vagrant. This is the features: Login with SSH + 2FA (Google Auth) No X No internet connection Copy unsigned transaction, sign it and ...
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1answer
203 views

Is there a way to split up my SSH Key using Shamir's Secret Sharing?

I have a few servers and machines that I regularly login to, so I was wondering if it was possible to secure them using a version of Shamir's Secret Sharing. I thought if I could split my private key ...
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175 views

how to create an encrypted ssh tunnel between local machine and final machine?

My machine at work is behind a firewall. To connect to it first i need to connect (ssh) on another machine and then through this machine i make the ssh on my machine. In other words, there is a middle ...
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Is sshpass utility insecure than manual ssh password authentication?

I'm planning to automate copying a large file to a remote server over ssh using rsync, using following command : sshpass -p '<PASS>' rsync --partial -av --progress --inplace --rsh='ssh -p 22' ...
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Surfing web anonymously on a mac using Firefox SSH and Tor [duplicate]

I want to download and upload to the internet anonymously. I have successfully configured Forefox to access internet through a secure SSH tunnel service (and remote server). I use 'SSH Tunnel Manager' ...
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Someone logged on my Centos VM; Can they attack the host OS?

I'm using Windows 7 and decided to learn Linux Administration (Centos 6.4) using Oracle VirtualBox to host the Linux system. In my network configuration I choose "Bridged Adapter". I set the VM's IP ...
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267 views

How do I find out if I'm connecting to a spoofed server after getting “The authenticity of host [hostname] can't be estabilished”?

I've been SSHing into my VPS for months with no problems and this morning it returned this familiar message: The authenticity of host '[hostname]' can't be established. ECDSA key fingerprint is ...
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408 views

Is SSH secure and what are the recommended modes of operation?

Given the recent confirmation of weakened and broken encryption schemes and implementations, how does the community feel about the security of SSH? It seems there has been very little discussion ...
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Is an SSH session to a mistaken site a security exposure?

A few minutes ago I attempted to ssh to a server I have at my office. Since it is a new server my public key has not been set up there so I had to type my password in manually. After three times of ...
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9k views

How to harden SSH on CentOS 6.5

I have a new (first time) CentOS 6.5 server being used for a web server. Our security team has identified the following weakness: The SSH server is configured to allow either MD5 or 96-bit MAC ...
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1answer
46 views

“holding open” encrypted home with local ssh

I have a couple of machines that I use for purely automated stuff, with home directories encrypted using ecryptfs. So even if the machine is powered on, those directories aren't decrypted unless that ...
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Do simple Linux servers really need a non-root user for security reasons?

Playing devil's advocate, Let's assume I purchase a Linux server from a hosting provider. I am given a password for the root user and am told I may login using SSH. The only purpose this server has ...
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What is the safest way to copy a file from an untrusted system?

Scenario: There are two computers running GNU/Linux, U and T. U is untrusted and T is trusted. A non-executable file F (which may however have been infected with malware) resides on U. (For ...
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531 views

PCI DSS 2.0 and ssh keys

I know the real answer to the auditor. We are a smaller company under 40 total employees that is also PCI level 1 compliant. We've always used ssh keys on internal servers. You can't ssh in from the ...
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355 views

How does SSH defend against keystroke-timing attacks?

This paper: https://www.usenix.org/legacy/events/sec01/full_papers/song/song.pdf Explains how SSH can be compromised by analyzing the timing of the keystrokes to guess what the user is typing. It's ...