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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21
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4answers
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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 /...
4
votes
1answer
109 views

Spoofing LAN IP Address Traffic

To give as much detail as possible, I am doing a Pentest for a client that has quite a few "terminal systems" meaning that they are simply a box with a connection back to the main server. These ...
8
votes
5answers
11k views

What are the ways to implement two factor authentication?

We have devices that can generate tokens. So we can use tokens with passwords to perform two factor authentication. There are many ways to implement such systems to enhance security. One of two I know,...
0
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5answers
749 views

SSH server: What's more secure, pub key auth or Google Authenticator time-based auth?

I'm curious which would be more secure, pub key authentication or 2-factor auth via Google Authenticator. Apparently I can't use both. If I have pub key authentication, the Google Auth PAM module ...
5
votes
1answer
75 views

Is OpenSSL generating Diffie-Hellman parameters that are safe for use in TLS or SSH servers?

I would like to generate Diffie-Hellman parameters on a Debian GNU/Linux "Jessie" 8 with OpenSSL. Lets assume the system CSPRNG was seeded with some real random data. On such a system, is the result ...
13
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1answer
2k views

Why OpenSSH deprecated DSA keys

There was a question RSA vs. DSA for SSH authentication keys asking which key is better. Basically all answers were more in a favour of RSA over DSA but didn't really tell that DSA would be somehow ...
3
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2answers
35 views

Should different versions of SSH give different VisualHostKeys?

I am SSHing to a server via Cygwin's SSH and via Ubuntu 14.04's SSH. Cygwin version: OpenSSH_7.1p2, OpenSSL 1.0.2e 3 Dec 2015 Ubuntu version: OpenSSH_6.6.1p1 Ubuntu-2ubuntu2.4, OpenSSL 1.0.1f 6 Jan ...
51
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6answers
8k views

Why is leaving a passworded SSH over the internet so bad?

I've heard multiple multiple times to never leave SSH with a password open over the internet. Why is this so bad? I understand the password can be bruteforced, but what if it is a very strong ...
3
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1answer
56 views

How secure is GSSAPI single-signon over SSH?

I know it is possible to integrate Linux/SSH logins with a Windows AD by using GSSAPI (Kerberos) authentication instead of the classic ssh keys and/or passwords. However, I have been unable to find ...
21
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5answers
2k views

Should I use a second/dedicated IP address for SSH?

When running a public web server (e.g., with Apache), I've heard it's recommended to bind SSH to a second IP address, different from the one Apache is listening to. But for me it seems like this is ...
1
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5answers
120 views

Best Security Method for SSH Access

I have been starting to think about security in a bit more depth recently and have hit a few questions which I would really value opinions on. For years I have had the same SSH Keypair to get to my ...
3
votes
1answer
834 views

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

Is it possible to use running SSH agent to decrypt some data (supplied as a string or read from file)?
10
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4answers
8k 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 ...
5
votes
1answer
286 views

Blocking Chinese IP addresses

I recently checked one of my servers' auth.log file and noticed some very suspicious activity. I recently shut down my server's ssh daemon, so the logs end on Jan 22, but what I noticed after ...
8
votes
5answers
3k views

What are potential security risks when using an insecure wireless connection?

If someone is using an insecure wireless connection (for example a hot spot in a coffee shop) does it pose a threat even if the person is using a secure application layer protocol? What I mean by ...
1
vote
1answer
107 views

SSH “on keyboard interactive devices” brute force vulnerability

I was researching the OpenSSH brute force vulnerability "onkeyborad-interactive devices", however I am not sure how this command really works ssh -lusername -oKbdInteractiveDevices=`perl -e 'print "...
2
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2answers
92 views

Protecting account ssh keys from root

How can users ssh private keys be protected from root stealing and attempting to brute force them? I cannot use selinux as the vendor will not support the app when it's in use? Thanks
56
votes
8answers
9k views

Am I experiencing a brute force attack?

When checking the auth log of a server with the command: grep sshd.\*Failed /var/log/auth.log | less I see thousands of lines like this: Jan 12 11:27:10 ubuntu-leno1 sshd[8423]: Failed ...
56
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7answers
10k views

Are passwordless SSH logins more secure?

I had a long discussion with my co-workers whether key-based SSH authentication (particularly for OpenSSH) is more secure than authentication using passwords. My co-workers always connect to servers ...
61
votes
8answers
14k 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? ...
128
votes
7answers
111k views

What is the difference between SSL vs SSH? Which is more secure?

What is the difference between SSH and SSL? Which one is more secure, if you can compare them together? Which has more potential vulnerabilities?
8
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1answer
2k views

Is it considered worth it to replace OpenSSH's moduli file?

Consequences of tampered /etc/ssh/moduli describes a possible risk if the moduli file for an OpenSSH server has been tampered with. Taking the logic a step further, is there any concern with the ...
24
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1answer
8k views

Consequences of tampered /etc/ssh/moduli

What are the consequences if an attacker is able to modify the /etc/ssh/moduli file?
2
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2answers
3k 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 ...
0
votes
1answer
77 views

Will the result of HTTPS and SSH encryption of the same data be identical for two separate requests?

If I was to request an image over HTTPS and record the packets over WireShark and then inspect a peer's Wireshark and look for the same packets, would I be able to see if they requested the same file, ...
2
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2answers
7k views

Break in attempts from secureserver.net

Over the last few weeks I have seen dozens if not hundreds of break-in attempts from ip addresses which map back to secureserver.net. I know these are GoDaddy machines from the who is look up. ...
1
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1answer
86 views

ssh tunneling /port forwarding/access different subnet

Hi I need some good pointer or any recommendation any docs about this below stated scenario. During in my recent pentesting : My ip is 192.168.x.1(kali) By some how I managed to get root shell on ...
2
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1answer
122 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
votes
2answers
143 views

Choosing between SSH and HTTPS for executing script using McAfee ESM Nitro

We intend to use McAfee ESM Nitro (SIEM) for security monitoring of our infrastructure servers. To bring automation in system administration of our servers, we have developed some applications in-...
0
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1answer
61 views

Is it a breach to have a ssh program into a tomcat server

I start to working in a project here and find something that at least seems odd to me. Since I'm not an specialist I came here to ask. It is a Java Web project that was made to run into a Tomcat ...
1
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2answers
1k 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 & ...
13
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2answers
3k 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 ...
0
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3answers
950 views

vpn vs ssh, what to choose? [duplicate]

First of all i am noob in this area so came here to get some idea from the experts. My friend was telling me the other day that ssh is pretty secure protocol and one should not be worried about ...
2
votes
1answer
143 views

What is the benefit of an SSH tunnel vs a Netcat shell for remote communication?

On the (few) penetration tests that I've done so far, I've typically created a reverse shell with Netcat to run commands on the target machine. Now, it looks like a lot of people like to use an SSH ...
3
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1answer
79 views

Security problems with password-less SSH

Is there any downside of configuring password-less SSH authentication? Although it is very handy and secure, if someone gets access to my system with my account and there is password-less ...
13
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1answer
3k views

What's the hash for in ECDHE-RSA-AES-GCM-SHA?

Presumably the SHA is for deriving the AES key from the shared secret. Where else is the hash used? ECDH just does ECC (no hashing). RSA does masking and padding but this doesn't involve the ...
1
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0answers
179 views

is it possible Windows privilege escalation using freesshd keys? [closed]

I have unprivileged shell one system.By browsing all folder i found freeSSHD folder Directory of C:\Program Files\freeSSHd 09/26/2008 02:07 PM <DIR> . 09/26/2008 02:07 PM <...
11
votes
3answers
7k views

How do I get SSH to prompt me with the RSA key instead of the ECDSA key?

I am trying to SSH into my fresh Ubuntu 12.04 server. At the client I have deleted known_hosts. SSH to the host for the first time has it offering me an ECDSA key to verify. The problem is I know ...
23
votes
2answers
40k views

How can I tunnel through an SSH server for application layer protocols such as HTTP/s and FTP?

Are there client programs that allow me to "tunnel" through my SSH enabled server for normal Internet requests such as HTTP(s)? If so what are they and can someone point me in the right direction? ...
1
vote
1answer
146 views

SSH Key vs Complex Password with Fail2Ban & Two Factor Authentication

Normally you hear that using an SSH Key is far more secure than using a regular password. However I've been wondering if this statement is really true. Let's say we have the following variables for ...
4
votes
3answers
954 views

How to secure a truecrypt container allowing access with multiple SSH public keys?

I would like to create a TrueCrypt container which can be accessed by multiple people. The container itself can be stored anywhere, e.g. in a shared folder in Dropbox or Google Drive, ... I would ...
2
votes
0answers
196 views

Why my proxy is still having some connections blocked

I am behind a firewall in France. I connect to proxy A, in Ireland with Dante via SSH port 22 and make a tunnel forwarding port 1080. The proxy works as expected but still having a port range blocked....
1
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2answers
82 views

What exactly does `ssh -T user@domain verify` do?

The example I'm specifically thinking of is: ssh -T git@github.com verify Looking at the docs (man ssh) I can see that -T is the flag to "Disable pseudo-terminal allocation", but what implications ...
4
votes
1answer
74 views

SSH Access to Personal Server sudo vs su

I have a server running Debian, which is on the web, and has few traffic (I use it essentially for some coulds, calendars, etc. for me). In an attempt to secure its access, I made the following in the ...
20
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4answers
2k views

Is it safer to ssh as a privileged user than to ssh and sudo?

I came across this old paper, discussing the possibility of password length information being disclosed when usin SSH: Timing Analysis of Keystrokes and Timing Attacks on SSH. The paper has been ...
2
votes
1answer
129 views

Is binding all private services to the 127.0.0.1 address and then accessing them via SSH using an RSA key pair of 4096 bits secure?

Is it secure to bind all private services only to the 127.0.0.1 address, and then use a local SSH client's local port forwarding with an RSA public / private key pair file of 4096 bits and a ...
0
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2answers
91 views

How much entropy should passphrases for encrypting ssh keys have?

When one generates keys using ssh-keygen one gets prompted for a passphrase to encrypt the generated key with. How strong should such a passphrase be, entropywise, to withstand a full-blown brute-...
3
votes
3answers
222 views

What should I be aware of when opening my home server to the internet?

I've built a home server (pretty much just a basic PC with a couple of big HDDs) which I would like to use as an FTP server and a minecraft server. Both would be for members of my gaming community. I ...
4
votes
1answer
2k views

ssh signature question (no matching key exchange method found)

I recently followed the advice at this blog to tighten down my SSH security, which included restricting key exchange algorithms to ones not vulnerable to known (or assumed known) capabilities of Prime ...
2
votes
1answer
186 views

How should I tunnel arbitrary protocol traffic over HTTPS?

I'm posting this question from a moving train! (Ok, maybe that's not so impressive.) This train has an annoying WiFi - it's low-throughput, high-latency, tends to lose packets, and blocks most kinds ...