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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Find the location of a hidden host

I'm doing a penetration test for a client who wants me to try and target a specific server. I have managed to get credentials(hard-coded in an in-house app) to a limited account on this server that ...
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What are the chances to generate the same ssh key?

I could generate ssh keys on the client like (without password): ssh-keygen -b 8192 -t rsa -f /home/THEUSER/.ssh/id_rsa -P '' -v and copy the generated id_rsa.pub to the server: ssh-copy-id -i ...
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1answer
71 views

Using given RSA private key without the associated public key

I'm currently following a small game to get more familar with linux and security and got the following task: The password for the next level is stored in /etc/bandit_pass/bandit14 and can only be ...
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2answers
60 views

Is it not safe to open MySQL's port to the internet?

The consensus on this Server Fault question seems to be that opening port 3306 for MySQL is more dangerous than using an SSH tunnel to access MySQL. I would think that with strong credentials you ...
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Is it a bad idea to share the ssh host key in a diskless environment?

I am looking at this cluster of student work stations. They are diskless clients which boot from NFS. They also have sshd enabled. All of these machines share the same ssh host key (rsa,dsa,etc), ...
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Brute forcing ssh keys

My problem is a common one: I deleted my SSH key, and forgot to set rm to point to a .trash file. I have the public key, and I need to get in this server. I am not doing this on anyone else's server. ...
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1answer
89 views

find passphrase on encrypted ssh private key

I have an openssh encrypted private key. I don't remember the pass-phrase. I may be able to suggest words or patterns that may be in the phrase. I am looking for software that will help me recover ...
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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 ...
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How can I make a read-only filesystem read/write?

I recently hacked into my router which runs BusyBox v1.9.1. I want to edit some files in my web GUI interface which will allow me to get hidden options in it. I'm trying to edit a .js file and replace ...
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35 views

Disable all SSH security mechanisms for a private subnet

So I'm running a private subnet where there is no internet connectivity, I understand the grave danger of running an ssh server on the internet without security. In short I would like to be able to ...
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1answer
21 views

What are the security issues of a MITM on an ssh session with rsa keypair

If a user connects to an SSH server using an rsa private key, but does not confirm the server's fingerprint. What kind of information can a man in the middle attack get from the session?
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83 views

Should remote access (RDP/SSH) only be allowed for VPN clients? Or should RDP and SSH be opened the public?

I am about to push hard against the powers that be and strongly recommend that we shift our many (20+) consultants from direct public access to RDP & SSH to VPN clients (connecting to a ...
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59 views

Linux SSH and GPG

Can anyone please give me a quick crash course on SSH and GPG? SSH: What is the difference between public and private keys? Should I back up my ~/.ssh/ directory, what are the security implications ...
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2answers
80 views

Storing SSH private keys on an Android device

(I'm not sure if this better belongs on unix.se or android.se, but since it's primarily security-related, I'm asking it here) I use my Android device to access servers for quick on-the-go ...
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Port forwarding does not work for http sites [migrated]

I am connecting to office network through VPN. I have two servers A and B. I have ssh tomcat access to A through VPN but not to B. When I ssh into A, from there I can ssh into B. Also, B is running ...
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1answer
218 views

Open source solution to capture and decrypt SSH traffic (with private key)?

I am looking for a free open source solution that is able to capture and decrypt SSH traffic given the fact that I can provide the server's RSA private key (something like SSH CryptoAuditor). Please ...
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1answer
87 views

Bastion host that allows jailed users to SSH but protects private key

Basically, I'm trying to let the user use a private key without having read access to it. Use case: Employee needs to SSH to a server in the data center. There is 1 private key for all servers, ...
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1answer
237 views

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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16 views

Is Mosh as secure as SSH? [duplicate]

Mosh, from my limited understanding of it, is a service which operates a shell over UDP. It claims to use SSH to initiate the connection, then starts the Mosh service on the client, and then connects ...
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63 views

Should I use more than 2048 bits in my SSH-2 RAS Key?

I've been asked to generate a public key with PuTTY Key Generator. The default is 2048 bits, Should I add additional bits to the generated key? Or is it unnecessary?
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279 views

Given an IP address can you ssh into /tmp without password?

I'm a Software Engineer, but I have no experience in security, so i'm trying to learn by doing (woot Experiential learning!). I know that the permission settings on the tmp folder are very relaxed. ...
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55 views

Can a SSH server or client to initiate a unencrypted connection?

Several clarifying questions: Is it possible to disable the SSH encryption using options at the OpenSSH server/client or some appropriate hack? Is it possible to do this at the time of the ...
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3answers
163 views

Working from many places <-> being able to restrict SSH access to server to IP range

I administer a webserver, and while I'd like to restrict the SSH access to an IP range, I wouldn't be able to do so because a) I travel a lot and b) I don't have a static IP at my homeoffice. I've ...
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2answers
41 views

can ssh port forwarding be detected?

say there are three players: A, B, C where A is local machine, B is ssh server, C is the final destination. through ssh local port forwarding, A can connect to C via B. So then data will be ...
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30 views

what is a server fingerprint in ssh?

Is is the same as a public key in RSA, except they made it more suitable for self-signed hosts? What happens behind the scenes when our ssh client presents it to us?
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184 views

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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2answers
47 views

Risk in connecting wrong ssh host?

I've a ssh host key login setup in a remote server, for some reason, the DNS of that host is mapped to another server. So assume the mistaken host cannot be trusted, should I change my key?
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49 views

unfamiliar IP when logging into ssh server

I just noticed something today, and Now I am curious... I was on my shell server, an i was wondering who was on, so I gave the command $w and saw this: j0h@server:~$ w 22:06:02 up 18 days, 7:02, ...
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1answer
210 views

Can an SSH server fingerprint be spoofed?

If I simply connect to an SSH server, get its key fingerprint, and immediately disconnect, does the SSH protocol ensure that the server also had the private key in order to get that far into the ...
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1answer
58 views

Practical advantage of requiring VPN for SSH

I have some VPS servers which I manage through ssh. However there are many ports which I want open during development, therefore I also have OpenVPN on them. Now I am wondering if it would make ...
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4answers
403 views

Is it secure to use *no authentication* for services listening only on localhost?

I have many applications installed on my server that use a webui frontend to control the application. Since I am the only user of the server, I usually bind these applications to 127.0.0.1. As the ...
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2answers
104 views

Encrypted offsite storage using sshfs and cryptsetup/dm-crypt/LUKS

I'm interested in an encrypted offsite storage scheme, but I don't want to depend on the vendor for encryption. I have an idea for doing so by combining sshfs with cryptsetup/dm-crypt/LUKS, but I'd ...
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831 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
173 views

Bypassing CVE-2010-4478 (J-PAKE parameter validation) in OpenSSH 5.1

Did anyone successfully exploit CVE-2010-4478 in the past? This is insufficient validation of the J-PAKE public key parameters in OpenSSH up to 5.6. I'm dealing with a vulnerable machine running ...
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2answers
111 views

Checking if a server is compromised

I do free/low-cost web/shell hosting as a non-profit organization (With a the same friend and co-founder) since 2007. We're on CentOS 6 + CPanel, and unfortunately we're still funding the ...
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1answer
1k views

Two-factor authentication with ssh key authentication and yubikey?

OpenSSH won't invoke PAM at all if public key (RSA) authentication is configured and the client presents a valid key. So if you use key-based auth, you can't enforce 2FA easily. One workaround for ...
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1answer
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Does SSH authorized_keys violate the principle of “re-authenticate before password change”?

It is generally accepted that password change mechanisms should ask the user for their old password (e.g. OWASP) The reason being that an attacker who has temporary access to a user's session (be it ...
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317 views

SSH connection attempts from China show different key; is China doing a MITM attack on SSH traffic?

I have a server located in the USA and SSH to it from various places around the world. When I SSH in from a computer I have never used before, I'll see something like this: The authenticity of host ...
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4answers
7k views

Brute-force an SSH-login that has only a 4-letter password

Suppose, you know that a certain computer is only protected by such a short password, then you could just try every possible combination easily. How would a script look like, that tries to crack that ...
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2answers
326 views

In there any point in passphrase-protecting an SSH private key that is used by a service account?

On my Linux machine (Alice), I am setting up a service account with an rsync cron job that will synchronise some files with a remote host (Bob). Obviously, I would want to make the rsync secure by ...
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462 views

Is piping a `ssh-agent` signed message as a password secure?

There's an encrypted filesystem on a server I ssh into using public key authentication. Since a forwarded ssh-agent can deterministically sign a message (see also the ssh-agent protocol section ...
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1k views

Is a passphrase-protected SSH private key susceptible to a dictionary attack?

If I have a passphrase-protected SSH private key, AND if this passphrase is sufficiently random and long (say, 20-, 30-, 40-characters long, or even more!), AND if I make this private key of ...
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1answer
39 views

Should statically-linked server binaries (daemons) be deemed more secure? [closed]

For a long time I've pondered this question. I am aware of the benefits and downsides of dynamic libraries (shared objects), including the infamous article by Drepper. All other things being equal, ...
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2answers
71 views

Creating port-specific SSH authentication for the same user

I have a Linux server running SSHD and would like to know if its possible to configure it, such that from within the LAN you only need a RSA key to authenticate (on port X), but from outside the LAN ...
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54 views

My server has been brute forced what now? [duplicate]

I have installed a raspberry pi for fun at home. I opened the port 22 and this morning I was concerned about someone brute forcing my server. I ran this query : cd /var/log;zgrep ssh auth*|grep ...
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1answer
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Is all data sent over SSH encrypted?

When you are connected to another computer over SSH, is all data transferred between the two computers encrypted? Or is any data sent in plaintext or any other "easy to intercept" format?
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153 views

How compromised should I assume my computer is?

I had turned ssh on a while ago to do some remote work, and didn't turn it off (yes, I'm an idiot). I was just looking over some netstat info when I noticed someone had established an ssh session with ...
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1answer
57 views

Simple way to protect ssh against man-in-the-middle attack? [duplicate]

If a narrow, trusted channel is needed (for example, there is an usb key to take data between the machines), it is okay. Although SSH will throw a big error if it tries to connect to a server ...
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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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3answers
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What benefit is there to adding a password to your SSH key?

If you run the following command on a Linux/Unix machine, among other things, you get a prompt for a password: $ ssh-keygen -t dsa Enter passphrase (empty for no passphrase): What does adding a ...