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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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 ...
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174 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 ...
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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 ...
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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 ...
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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 <...
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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 ...
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2answers
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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? ...
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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 ...
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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 ...
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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....
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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 ...
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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 ...
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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 ...
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1answer
141 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 ...
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2answers
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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-...
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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 ...
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1answer
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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 ...
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1answer
228 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 ...
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Can IP address be a component of 2-factor authentication?

I have a bunch of Linux machines that I wish to administer over the Internet. I currently use SSH keys, but have been advised to use 2-factor authentication. SSH Keys are something you know. Is an IP ...
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SSH intrusion suspected: Logwatch report versus SSH log file entries

My Web server's Logwatch report shows ssh and su activity that should not be there: sshd: Sessions Opened: deployer: 45 Time(s) su: Sessions Opened: root -> deployer: 8 Time(s) ...
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On the Import Client Key screen in Bitvise what is numeric field just next to the Location Profile dropdown?

What is this field for? I know I saved a profile in the beginning, and I want this private key to be attached to just the profile that I'm using, but what on earth is that numeric field for?
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Is the ssh-copy-id command secure?

I have 2 Ubuntu 14.04 servers with openssh-server installed on both. I've set up key-based authentication using RSA keys, without passphrase, so that I can run automated backup scripts, to a remote ...
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Is CurveZMQ Mature Enough to be Trusted?

We're using ZMQ for our projects and are now looking at extending usage to traverse a LAN. We'd like to implement security as this LAN could potentially have hostile parties. I'm leaning towards ...
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1answer
443 views

Do SSH private keys always contain enough information to derive a public key?

I am working on a persistence model for SSH Private keys. The technology used is Java. Since the persistence structure of the public and private keys is pretty similar and using some of the Java APIs ...
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Generate RSA2 key in OpenSSH format in windows

I have to generate a key, RSA v2 in OpenSSH format. I am a bit confused. I am trying to generate it using Putty key generator. There I see an option SSH2-RSA and SSH1-RSA. So is SSH2-RSA the RSA2 key ...
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Likely Sources of MITM Attack over Public Internet SSH

Earlier today when attempting to ssh into my remote server, I got the standard man in the middle warning relating to inconsistent public keys. In fact the key-type wasn't even correct. My server uses ...
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Should I use more than 2048 bits in my SSH-2 RSA 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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Should I worry if I have tried to ssh into a 'fake' dyndns.org site? (with ssh keys)

I often ssh into servers for work and play using dynamic dns with ssh keys that are password protected. Twice now (shame on me!) I have mistyped the dyndns.org part of the address and been greeted ...
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SSH Server Authentication

I know this question was asked several times in several ways, for example: Can an SSH server fingerprint be spoofed? What stops an SSH server from MITMing logins? However, none provided the ...
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How do I know a new host key is safe to accept?

I am frequently rebuilding servers for staging and development. I connect to them with SSH for provisioning. In the process, I'll destroy a VM, rebuild it, and provision it all over again with the ...
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Docker X11 Forwarding Security

I am currently running a Docker container with a program with a GUI forwarded over SSH (using X forwarding over OpenSSH). The virtualized server has X11Forwarding enabled and I can connect to it from ...
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1answer
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Does a VPN provide any security benefits over sshuttle or a vanilla ssh tunnel?

I use sshuttle to tunnel my traffic through one of my remote boxes whenever I'm in a cafe or connected to an insecure network. Does a VPN provide any additional security benefit over this kind of ...
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What are the advantages/disadvantages of changing the SSH/SFTP port in Linux?

I have setup a remote CentOS VM (through a host) for our websites. I read an online recommendation to change the default SFTP port from 22 to a higher port such as 22000. I understand it is security ...
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Does public key auth in SSH prevent most MITM attacks?

I found this article that claims asymmetric crypto signature of DH-obtained key prevents MITM: http://www.gremwell.com/ssh-mitm-public-key-authentication Key idea: The value of 'signature' is a ...
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2answers
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Secure protocol for a backup server? [closed]

I want to make a back up system in my home, but I don't know I should use a FTP server or a TPC-based cloud server or a SSH-based server. Which method is best in security? I just want to upload and ...
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4answers
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SSH key auth, but still need password for sudo?

SSH with public-private key authentication comes enabled by default with most Linux distributions. This is great because when I create accounts for remote users I don't have to email them sensitive ...
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Wayland Partial Encryption for Mouse / Keyboard? (Also X and RDP)

Question What are the best practices for implementing Partial Encryption, to encrypt just the input devices (mouse/keyboard, etc), not the actual video display, during remote desktop sessions using X,...
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Does SSH use one pair of keys for encryption or two pairs of keys?

When SSH(OpenSSH) client connects to SSH server, then SSH server provides its public encryption key(for example /etc/ssh/ssh_host_rsa_key.pub) to SSH client so that SSH client can encrypt data sent to ...
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SSH attempt blocked now ECDSA keys changed

Last night I had an external IP tried to access my server over SSH. The attempt was blocked as it failed to authorise in the number of times and time limit that I'd specified. Doing a whois on the ip ...
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“Fix” man in the middle

I've just tried to ssh connect to a server (auth via ssh key), and get the well-known message WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!. I'm the server administrator (but I'm not really a good ...
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5answers
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How does a network admin block the reverse SSH in company?

Given firewall inbound: all are blocked outbound: allow port 80, 443 Problem colleagues are still able to ssh to home device by port 80/443, and establish a reverse ssh tunnel from company to ...
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1answer
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How Google has an SSL certificate from itself and my browser doesn't give an error [duplicate]

I know that I can create my own SSL certificate, but in this case the browser will give 'not trusted' error to the user, as the certificate is not browser trustworthy. So companies go and get an SSL ...
3
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1answer
2k views

Decrypt SSH traffic in pcap file given private key

I have a Pcap file that contains some SSH encrypted packets. I have the server public and private key. How do I decrypt these private keys? Is it possible to get the session key using Wireshark or ...
4
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2answers
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Does changing /etc/ssh/moduli impact previously generated keys?

My company does a lot of automated file transfers over SSH/sftp with banks, etc. A recent SSH upgrade on a server dropped support for the old/weak diffie-helman-group1-sha1 key exchange protocol in ...
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3answers
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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 2.6.2),...
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Should I generate new SSH private keys for each machine I work from?

I hope this is an appropriate place to ask this question. I've been thinking recently about public and private keys, and I'm wondering what the best practices are related to management of my own ...
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1answer
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How are man-in-the-middle attacks actually implemented? [closed]

For research purposes. I'm wondering, in a high level way, how MITM attacks are actually done in the real world. So over the internet the client talks to the server, or one person emails the other, ...
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2answers
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Isn't ssh-copy-id exposing to a brute force attack?

It is a common knowledge, that using keys to authenticate ssh users is more secure than using passwords. However, even with password login disabled, when running ssh-copy-id I am still asked for user'...
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1answer
195 views

Are there any risks associated with SSH agent forwarding?

I just realized that I need SSH agent forwarding in order to push to one Git server that then forwards the commits to Github.com. I never used SSH agent forwarding and don't understand the security ...
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How is the server authenticated in ssh? [duplicate]

The server does not know any secrets that can be used to authenticate itself. Also, what good is a fingerprint if it is based on the public key if it is basically the hash of some known public key. ...