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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35 views

Use SSH config file with Putty [on hold]

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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1answer
52 views

Most secure SSH server [on hold]

Which SSH server (compatible with Debian Wheezy) has the fewest (if any) exploitable security bugs?
5
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2answers
208 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 ...
1
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1answer
47 views

Multiple users, Multiple servers, SSH key management

Here is the situation. I have 5000 servers broken into "groups" of 100. Each "group" has 1 SSH key pair, that will allow access to any of the servers in the group. I have 60 users(some human, some ...
5
votes
1answer
66 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 ...
0
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1answer
70 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, ...
0
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1answer
52 views

Outbound Port 443 Open but Not Allowing SSH [on hold]

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 ...
8
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3answers
1k 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 ...
5
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2answers
440 views

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 ...
4
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3answers
493 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 ...
0
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1answer
715 views

How to use public key in ~/.ssh for asymmetrical encryption with OpenSSL

I want to do an asymmetrical file encryption: openssl genrsa -des3 -out private.key 4096 openssl rsa -in private.key -pubout -out public.key openssl rsautl -encrypt -pubin -inkey public.key -in a ...
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1answer
51 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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0answers
27 views

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 ...
6
votes
1answer
87 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 ...
0
votes
1answer
73 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 ...
2
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1answer
77 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 ...
6
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3answers
100 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 ...
2
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4answers
311 views

Is there a way to keep sudoers from editing stuff in /etc/ssh/sshd_config?

I have root login disabled in SSH and I want to be able to eliminate the possibility of a sudo user editing the /etc/ssh/sshd_config file and enabling root ssh login. Is this possible?
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3answers
105 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 ...
2
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0answers
63 views

Router eavesdropping on SSH tunnel? [migrated]

So I'm on a public WiFi network that blocks websites like YouTube in order to conserve bandwidth. I'm assuming the router is monitoring all traffic and rejecting all requests sent to the sites on its ...
3
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3answers
179 views

Is it advisable to fully record terminal interaction for incident response?

We are going to be using a jump box to serve as an SSH bridge to our production systems. Assuming that operators are actually logging in to a shell on the jump box and assuming that it is possible to ...
5
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3answers
102 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
41 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
126 views

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 ...
3
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3answers
1k views

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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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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3answers
475 views

In what ways does increasing SSH host key length increase security

I have read on a few guides on "how to secure SSH servers" that it is a good thing to increase ServerKeyBits from the default of 768 to 2048. Most of these guides seem to be for the entry ...
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2answers
69 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 ...
13
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2answers
2k views

stronger encryption for SSH keys

I configured my server to encrypt user passwords using 500,000 rounds of SHA-512. The question is, how does the standard AES-128-CBC encrypted SSH private key stack up to that, provided the same (or ...
3
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4answers
190 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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2answers
103 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 ...
3
votes
1answer
3k 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 ...
0
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1answer
65 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, ...
2
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1answer
92 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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0answers
30 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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3answers
124 views

Would SSH MitM attacks utilize spoof IPs?

I am presented with SSH log from a SSH server and the said SSH server only accepts connection from 2 known public IPs over WAN. The content of the log shows that a user was successfully ...
0
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1answer
41 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, ...
19
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2answers
1k views

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 ...
1
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1answer
129 views

Do I need logging enabled in my rules in IPFW for sshguard-ipfw to work/blacklist ip's?

From the FreeBSD handbook: Even with the logging facility enabled, IPFW will not generate any rule logging on its own. The firewall administrator decides which rules in the ruleset will be ...
3
votes
1answer
103 views

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 ...
0
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1answer
143 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 ...
0
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2answers
137 views

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?
149
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7answers
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RSA vs. DSA for SSH authentication keys

When generating SSH authentication keys on a Unix/Linux system with ssh-keygen, you're given the choice of creating a RSA or DSA key pair (using -t type). What is the difference between RSA and DSA ...
4
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3answers
247 views

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 ...
10
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3answers
2k views

SSH password vs. key authentication

I've usually been told that public key authentication is strongly preferred over password authentication for SSH. However our previous admin was against public keys and only issued passwords and took ...
3
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1answer
171 views

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 ...
0
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1answer
97 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 ...
4
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1answer
115 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 ...
3
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1answer
718 views

How can I detect if someone is using an ssh tunnel as a proxy to connect to a VPN?

I've got an SSH server setup in a remote location, which I use to tunnel traffic from an android tablet. On the tablet, I have the Cisco AnyConnect app to connect to my company's VPN. We want to be ...
6
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3answers
10k views

Converting keys between openssl and openssh

If I use the following openssl req -x509 -days 365 -newkey rsa:2048 -keyout private.pem -out public.pem -nodes I get private.pem and public.pem If I use ssh-keygen -t rsa -f rsa I get rsa and ...