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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Can public keys be a security risk when performing password-less SSH logins?

Some companies use monitoring software such as nagios or icinga. In order to perform checks on the servers, they often need password-less SSH logins. The servers being checked put the public key of ...
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Creating user specific authentication methods in SSH

I have configured sshd on an Ubuntu server to use key authentication and it is working fine. I had to disable password authentication for key authentication to work. Server is always accessed via ...
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Possible to use both private key and password authentication for ssh login?

It seems that they are mutually exclusive, as disabling one gives me the other, and vice versa. Two-factor auth for my ssh servers sounds really nice, so is there any way to accomplish this?
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Do these mysql and ssh issues mean my rails server was hacked?

I'm running a rails application on an ubuntu server on slicehost. I got a pingdom alert that the server was unreachable, so I tried to load the website in my browser. It showed a Passenger error, ...
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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 posse a threat even if the person is using a secure application layer protocol? What I mean by ...
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In the Diffie-Hellman key exchange, how is the shared base key 'p' known and how are A and B, protected from Eve?

I'm trying to wrap my head around Hellman, Diffie, and Merkle's key exchange design, but after reading the Wiki article about it, I can't figure out how the commonly known factor ('p', I think) comes ...
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How often should an SSH key pair be changed? [duplicate]

Possible Duplicate: How often should an SSH key pair be changed? I've been using a passphrase-protected 1024-bit RSA key for passwordless SSH via ssh-agent between my own systems for years. ...
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How often should an SSH key pair be changed?

I've been using a 1024-bit RSA key for passwordless SSH between my own systems for years. More recently I've also started using it for passwordless access to my hosting providers and to source code ...
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SSH : Remote Host Identification Changed

As part of my daily routine, I was SSH'ing to one of the corporate servers. However this time I was presented with following message @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ ...
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Security Concerns with X11 Forwarding

What are some of the security concerns and reasons either for or against allowing X11 Forwarding. I have generally taken an approach of not allowing it under the blanket guise of security. Recently, ...
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Is there an easy way to see a log of SCP activity on a server (ala /var/log/secure for ssh login)?

On Linux systems, /var/log/secure (or similar, depending on distro) shows all SSH login activity. Is there a similar log for SCP? If not, what's a good approach to enabling logging of scp activity ...
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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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What's the safest way to access my US-based bank's website from within Mexico? VPN vs SSH vs HTTPS?

I will soon be moving to Mexico and living there for an extended period. During that time I will need to occasionally access my US-based bank's website. I'll always be connecting using my own laptop, ...
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414 views

Monitoring and filtering of arbitrary outgoing data

I would like to be able to not just centrally monitor but also filter any organizational data moving out our edge routers, regardless of the sender application and regardless of the protocol/port used ...
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1answer
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What would the high priority steps be for securing a small (cloud) application?

No doubt there is much good information at this link on hardening a linux server and at the child links off of that. And at this link to relevant tools it seems there has not yet been a popular ...
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Secure use of psexec or better alternative to it

I want to remotely start VMWare virtual machines (I own VMWare Workstation) and to this end I need to execute on host something like "vmrun -T ws H:\VMWare\VM1\VM1.vmx nogui" with user desktop ...
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1answer
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File directory deletion [closed]

So I heard this guy talkin about how one time he deleted someone's windows directory remotely. He claimed to have gotten into the system and deleted it such that the files are all still there, but the ...
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1answer
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Protection against a fired IT employee [duplicate]

Possible Duplicate: When a sysadmin leaves what extra precautions need to be taken? We have some servers on two sites. We use Puppet to allow only SSH key (root denied) and authorize users ...
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Can ssh keyfile security be broken in a few hours if the file is exposed?

At this link there is a claim that if an RSA key has a strong passphrase security might be broken in a few hours if an attacker has the private key. Is there something weak about the security of RSA ...
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Taxonomy of Ciphers/MACs/Kex available in SSH?

SSH offers a large variety of algorithms for Ciphers, MACs and KexAlgorithms configuration options. Sometimes I need quick and light (my own internal network), and sometimes I want all the ...
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Recently set up a server, Need security help

I set up a server running debian I opened port 22 allowing access to ssh into the port. I keep getting weird messages in my router log saying: [LAN access from remote] from 211.161.46.101:57201 to ...
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Is IP spoofing relevant to TCP? Is it relevant for TLS or SSH?

I have read the TCP Connection Establishment on Wikipedia In brief the packets to start are SYN, with a (hopefully) random sequence number A from the client. SYN-ACK, responding, with A+1 and ...
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Does TLS-OBC only improve security of Web Browsers? Does it improve the security of SSH?

I'm studying the TLS-OBC extension and would like to know if it improves security of non Web-based protocols? Specifically, would it be of any benefit to SSH clients? (version 1 or version 2.x/secsh) ...
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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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Smartphone SSH clients with shared user

I am writing an application for smartphones to provide very limited SSH usage. The user cannot perform arbitrary actions when logged in. They can run a specific script(s) only. For various reasons ...
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Is it less secure to use OpenDNS for banking accounts, SSH, Adsense account?

I have one WiFi connection in my house which I use for my iPad, phone and computers. I want to block adult sites, time consuming sites for every device that use the WiFi connection. So I came across ...
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Encryption laws in India — is it allowed to use ssh and VPN?

I have a very similar question to the one asked here (regarding Iran). However, I would like to use ssh and vpn while being in India. I found already this survey of cryptographic laws but I don't ...
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can ssh passwordless public key authentication be ok if combined with a VPN?

Having a debate with a coworker about the merits & faults of public key authentication with ssh. I'm basically wondering what all the possible merits and faults are, especially in regards to ...
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Dropbear SSH server use-after-free vulnerability

"This vulnerability is located within the Dropbear daemon and occurs due to the way the server manages channels concurrency. A specially crafted request can trigger a use after free condition which ...
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Is it OK to use the same password for a Linux login and the SSH private key?

I want to remotely log in to my Linux server with SSH. Public/private key authentication is more secure than password authentication, so I have disabled password-based authentication for SSH on my ...
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Which is the most vulnerable to MITM attacks, SSL or SSH?

Which is the most vulnerable to MITM attacks, SSL or SSH? Here's the scenario, you have 20 minutes to set up a web proxy like this: Laptop -> Chrome Browser -> Web Proxy -> Internet You must secure ...
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Encryption-Laws in Iran

According to this article Iran has criminalized the usage of encryption and VPNs. According to this blog post it is still possible to use SSH tunnels in Iran. For me SSH is encryption and thus ...
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What's the common pragmatic strategy for managing key pairs?

I have a small number of different workstations (plus client devices like iPhone) that I use for to connecting to numerous servers using SSH. Originally when I learned about PKI, I created a single ...
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1answer
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Fail2Ban does not ban failed root login attempt

I have a small server which only open ports are ssh, http and https. I have fail2ban installed and set up so that after 3 failed attempts someone gets blocked for 10 minutes (thats the dafault I ...
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1answer
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Security issues related to public keys and SSH

Do I have to mind something specific when using public keys and SSH? Well of course, I have to keep my private key secret (and therefore I should choose a strong pass phrase). But is there something ...
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ECDSA Keys Changed, SSH insecure now?

I'm running some non-critical Ubuntu servers in my dorm room in college. Turned them off before break, come back, SSH in, and get a warning that the ECDSA keys have changed. It looked pretty much ...
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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 ...
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Reusing Private/Public Keys

I have accounts on several third party sites - Bitbucket, Bluehost, etc. From what I've gathered, it is common practice to use one key pair for all [id_rsa, id_rsa.pub], but only to give out the ...
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Public wifi security protocols

I should apologise first- this post could seem a lot to ask for, but I am starting to go around in circles. I am interested in securing my laptop for when I use public wireless hotspots, as I am a ...
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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 ...
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2answers
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SSH Tunnelling: How can I stop users being able to access services bound to localhost via port forwarding?

I want to be able to offer ssh accounts on my linux server for people to be able to use for SSH tunnelling. All accounts will be locked down with no interactive shell, for tunnelling / port forwarding ...
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How can I convert my encypted PGP secret key for use performing SSH authentication?

I wish to covert my PGP key (RSA) to be used performing SSH authentication. After some searching, I found openpgp2ssh, which appears to be an appropriate tool. Everything works swimmingly for my ...
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ssh public/private key pair

I am having problems understanding how ssh really works. I know it uses a public key cryptography to encrypt messages. However, I can ssh to a server without first generating a public/private key pair ...
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What are the security implications of SSH tunneling?

We have an internal lan (not connected to internet, all internal ip addresses, behind a firewall, no routing to outside), we also have a machine that sits on the edge of our lan (two nics, one on the ...
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Sudo password when authenticating via passwordless SSH

I've got a few boxes all networked together on Amazon EC2, each of which are in automated communication with each other via SSH (rsync, etc). As such, I've created SSH keys on each of these machines ...
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What is the security implications of enabling SSH onward connections

I was reading SSH tips and tricks from http://blogs.perl.org/users/smylers/2011/08/ssh-productivity-tips.html There is a section on Onward Connections and the author warns not to use this unless you ...
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Is there a reason to disable root login, if SSH connections are restricted to a single IPv4 address?

I have a linux server running centos, and while hardending the SSH server, I asked myself: Is there a reason to disable root login, when only I (assuming my IP address is static, and i have direct ...
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Consequences of compromised /etc/ssh/moduli

Hypothetically, what could an attacker achieve if they have a copy of of /etc/ssh/moduli?
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How is tunnelling SSH through Poxytunnel/HTTPS different from doing it through SSL with Stunnel?

In an answer to What is the difference between SSL, TLS, and HTTPS, it's said that HTTPS is HTTP over SSL/TLS. That is, an SSL/TLS connection is established first, and then normal HTTP data is ...
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Risks of ssh to an untrusted host?

I use ssh a lot to connect to a variety of servers at my university. The machines are administrated by students, so assume they can't really be trusted;-) What are the risks in making a ssh ...