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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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, ...
2
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2answers
170 views

Mount ecryptfs directory via SSH

I have access to a server that I use for backups. I use rsync with the --delete flag to make an exact copy of my backup directory. I have no need for incremental backups. The backup directory on the ...
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2answers
236 views

What are the risks associated with SSH'in from corporate LAN to untrusted server on the Internet

At work (a huge organisation) I found a server on the LAN that opens SFTP connections to 2 servers across the Internet. I assume the remote hosts are in the other parties DMZ. I know you are not ...
2
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1answer
117 views

someone may be doing something nasty

I have an ssh server. earlier toady, I was about to login to my server, when I got a message that said something along the lines of "Someone may be trying to do something nasty" and indicating a man ...
2
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1answer
25 views

How is composed “public host key and certificates (K_S)” in SSH_MSG_KEX_DH_GEX_REPLY message? (SSH2 key exchange)

I'm trying to implement SSH2 key exchange in Java, and having some difficulties. The RFC4419 states, that: The server responds with: byte SSH_MSG_KEX_DH_GEX_REPLY string server public host ...
42
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7answers
9k views

Should I change the default SSH port on linux servers?

Is there any advantage in changing the SSH port, I've seen people do that, but I can't seem to find the reason why. If you have a strong password and/or a certificate, is it useful for anything? ...
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2answers
30k views

Secure Configuration of Ciphers/MACs/Kex available in SSH

Following on the heels of the previously posted question here, Taxonomy of Ciphers/MACs/Kex available in SSH?, I need some help to obtain the following design goals: Disable any 96-bit HMAC ...
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1answer
77 views

SSH: What's the difference or interplay between /etc/ssh/[host files] and ~/.ssh/[public key]

I'm new to SSH after a decade of dabbling with Ubuntu and other Linux builds. Today I successfully setup SSH, but I had a few hangups and headaches along the way. Although the system is now running ...
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1answer
70 views

Single vs server specific ssh keys?

This question has a bit to do with procedure. Is it better for a person to have one single ssh key pair and share the public key where needed. Alternatively is it better to have server specific keys? ...
2
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1answer
53 views

Using Google Authenticator for SSH sessions

So I have an SSH tunnel which I use with dynamic port forwarding to the alternate http port on the client. For initializing this connection, I'd like to implement an additional verification step, ...
2
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1answer
117 views

How to view all SSH authorized_keys for a unix server

How would I view all the authorised SSH clients from a unix server? I know that cat ~/.ssh/authorized_keys shows authorised keys if logged in from root. Can other users set their own authorised keys ...
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1answer
80 views

NISTIR 7966 (Security of Automated Access Management Using Secure Shell) - is there anything new?

Tatu Ylönen (the creator of SSH protocol) and two others authored a report recently, offering their views on SSH key management. I have read the report, and am struggling to identify whether it is ...
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0answers
138 views

Metasploit ssh_enumusers stops instantly [closed]

When I try to run the : http://www.rapid7.com/db/modules/auxiliary/scanner/ssh/ssh_enumusers using the given options besides proxies I get the output: msf auxiliary(ssh_enumusers) > run [*] ...
4
votes
2answers
235 views

Is it safe to store a passphrase encrypted SSH key in git?

I have a bunch of servers that need to access somewhat sensitive data (passwords for ftps, api keys, etc). Currently I copy a plaintext file back-and-forth between the servers via ssh and encrypt all ...
0
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1answer
36 views

Custom publickey authentication

I'm working on a REST account management system over https that should support both username/password and username/publickey authentication schemes. I.e. when a user registers an account, they may ...
5
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1answer
69 views

Relationship between HTTPS and SSH Public Keys

I can use my private key to generate a public key for use with ssh. I can use the same private key to generate a CSR, to generate a CLIENT certificate for HTTPS. Specifically, my SSH public key is: ...
0
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1answer
56 views

Is it worth it to use sshguard when only allowing ssh login from specific IP?

I'm running a VPS (under ArchLinux) and was wondering if sshguard was useful in the following case. My iptables rule for SSH in looks like this : iptables -A INPUT -p tcp --source $Trusted --dport ...
130
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11answers
14k views

What alternatives are there when SSH is being actively filtered?

Unfortunately our government filters the SSH protocol so now we can't connect to our Linux server. They do the filtering by checking the header of each packet in the network layer (and not by just ...
33
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2answers
5k views

I accidentally published my SSH key passphrase, what to do?

So I mistook input fields and now my SSH key passphrase is visible to the world, and I can't even remove it. Now as far as I understand, this is not an immediate security concern, since the ...
2
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2answers
197 views

Lots of SSH tries on my log. Is it normal?

I have a Raspberry Pi connected to my home and at day 2 of this month I've opened the port 22 of my router so I could SSH it from anywhere. Today by curiosity, I decided to see the raspberry pi log, ...
2
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1answer
75 views

Do I have an SSH password?

I have an Ubuntu server hosted on DigitalOcean, I have been using SSH keys since the very beginning. (You can chose for it to be setup before the server instance has even been created). So I have ...
0
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1answer
87 views

Would the authorities in my college be able to see what websites I accessed through tunneling(SSH)?

I study at a college where most social networking sites are banned(Including this one) and if someone is found using them somehow is heavily fined.I just want to know what all can the network admin ...
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2answers
103 views

Do GPG and OpenSSH use key stretching on their keypairs?

Both OpenSSH and GPG can generate key pairs which are stored as files in well-known paths inside the user directory. A passphrase is always asked for during the generation process, which is then used ...
2
votes
1answer
307 views

difference between public key and host key and security of host key

In SSH, what is the difference between host key and public key. Public key I believe that is part of private/public key pair, so, that anything sent by server(encrypted using private) can be ...
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1answer
113 views

Security of access to local network via VNC over SSH tunnel

I've just set up a Raspberry Pi 2 with the latest raspbian and installed some services. For remote access I've installed tightvnc server which I set up to only allow connections from localhost. I can ...
3
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1answer
116 views

How to deal with SSH keys in insecure environment

I am trying to find out a "safe" solution for the following situation. tl;dr how to keep things secure in an environment that is absolutely not? I work in a company where workstations are not safe ...
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1answer
77 views

Choosing a cipher and MAC for an SSH connection

The cipher and mac selection according to this are in some sort of order in a config file. How do the client and server know that they are using the same ones though? Is this information exchanged in ...
5
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1answer
177 views

Is port forwarding inherently unsafe?

I had an argument with a person a few months ago when I proposed we forward port 12xyz to an internal SSH server. The target server was tied down in a manner similar to the one recommended by ...
2
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2answers
44 views

non-https winscp website

The whole point of WinSCP is to provide a secure channel between a computer and a server. "Secure" means that there is a possibility of an attacker that can view or modify bytes sent both ways. Let's ...
2
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2answers
222 views

Expiration / enforce change of passphrase for private ssh keys

Out of curiosity, and also to check whether this is doable at all: Is there any way using standard tools to assign an expiry date [only] to the passphrase of an ssh private key, or to enforce the ...
14
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2answers
18k views
8
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1answer
219 views

RSA key generation: gpg vs openssh

When I generate RSA key for ssh (both server-side and client-side): dpkg-reconfigure openssh-server ssh-keygen the key generation is completed instantly. However, when I generate RSA key for gpg, ...
4
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3answers
562 views

SSH Public Key Authentication vs Username/password for API Access

I have a linux device that will be making periodic call to an API server, say everytime the system boots up. Everytime then it should authenticate itself and then do its thing. I can either store the ...
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5answers
8k 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 ...
4
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3answers
710 views

Is it always better to put authorized_keys in one's own .ssh directory rather than in root's .ssh directory? [duplicate]

I connect via ssh to multiple Linux servers during the day from my Mac's Terminal window. On my Mac I have the public and private keys in my .ssh directory. On the Linux servers I always use "sudo ...
0
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2answers
148 views

Is there a risk in opening port 22 for ssh access with a network? [duplicate]

Background We have our own datacenter which houses platform specific environments and each environment is isolated. Eeach environment is also has 3 tiers (Web Servers, Application Servers & ...
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2answers
59 views

Determining a version of SSH from penetration testing?

I am a software developer -- but not a security specialist. A (legitimate) company that does security scans sent my company a notice that we are running an older version of SSH on our hosting server. ...
3
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1answer
150 views

OpenSSH downgrade attack

I have tried to implement a downgrade attack against the SSH protocol as the first steps (encryption protocols exchange) are not signed, as per RFC4253. The idea is to intercept (mitm) these steps and ...
2
votes
1answer
277 views

Does OpenSSH use export ciphers?

With all of this talk of 'FREAK', no one has mentioned OpenSSH. It implements libraries from OpenSSL (until recently, anyway). Why aren't people talking about this? is there even a way to configure ...
256
votes
7answers
205k views

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 ...
3
votes
3answers
919 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 ...
5
votes
2answers
133 views

Share root access without sharing password

I am looking for a way to share admin privileges on some hosts without providing the admin password. From his link, I was thinking of using a primary host from which every user can sudo -u user to ...
1
vote
1answer
316 views

End-to-end encryption with a reverse proxy and an application server

Lets say that I have an nginx reverse proxy that proxies the traffic to a Tomcat on the same server. I think the most common way to configure this setup is to enable SSL on nginx and then proxy the ...
7
votes
1answer
261 views

Are these SSH passwords of hacked servers?

I have been seeing persistent SSH connection attempts on my computer from a familiar IP address. I got curious and decided to do some Googling on the IP address. Turns out that someone from Indonesia ...
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4answers
17k 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 ...
0
votes
2answers
384 views

How can I block certain IP addresses from my router?

I have done some basic things protect my router like disabling wps setting strong passwords and stuff. However, I am using a virgin media superhub 2 where it does not seem to be possible to ssh into ...
8
votes
1answer
282 views

Visual fingerprint verification

OpenSSH allows to show a visual representation of fingerprints with the VisualHostKey, see announcement at O'Reilly and here. The output looks approximately like this: # Host github.com found: line ...
4
votes
1answer
125 views

Linux/ssh - Forensic question

In a Linux terminal, I made a ssh connection from A to B and I used commands to read some files stored in B. Then I disconnected and I closed the terminal. Is it possible to find on A, informations ...
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1answer
107 views

Same RSA key pair for all users

Let's say in my computer running Debian i have an RSA key pair generated by user foo and copied the public key to server_A for allowing key based authentication in ssh for foo. Now my question is can ...
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1answer
53 views

Can a compromised OpenSSHD server be used to upload a malicious payload to a client?

Since I'm fairly unfamiliar with the specific details of the SSH protocol, I was wondering if it was possible for a compromised SSHd server to upload a malicious payload (like a Trojan or some other ...