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Questions tagged [ssh]

SSH (Secure shell) is a protocol for secure communication between computers to execute remote commands, transfer data and tunnel TCP connections.

0
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1answer
66 views

How do these attackers find my IP? [duplicate]

Recently, I have been reading a lot of my ubuntu log files (in /var/log/auth.log), and I can see that some IP addresses are actually trying to 'brute-force' their ways into my VM using SSH by testing ...
0
votes
1answer
29 views

Use GPG smartcard and gpg-agent to protect multiple SSH keys

I have a Yubikey acting as a GPG smartcard. SSH is configured to use the smart card socket for authentication, and authenticating with the GPG key with Authentication capabilities work fine. ssh-add -...
0
votes
0answers
44 views

SSH-1 key length

What is the maximum size in bits of one SSH-1 key? 4096? I found some docs where this value is listed and others without limit
0
votes
1answer
71 views

Techniques used by highly sophisticated entities to snoop on VPN or SSH traffic?

It is mentioned in almost every where that very strong agencies, and governments are able to watch the online activity of the people. Aside from techniques like attacking computer networks, and ...
1
vote
0answers
8 views

Sending file from Linux to Windows with SCP Comand [migrated]

I know there are allready some threads about this but still none of them helped me to solve my problem. I want to send a simple text file from my Linux machine to my windows 10 pc using the spc ...
2
votes
1answer
77 views

Risk involved with using SSH for CTF challenges? [duplicate]

I'm new to the INFOSEC scene and was intrigued by the concept of CTF challenges. I was hoping to get started with OverTheWire.org which requires you to SSH to their server to complete the challenges. ...
1
vote
1answer
60 views

Why can I use 2 different private keys to connect to my SSH server storing only 1 public key?

On my server ~/.ssh/authorized_keys contains only 1 public key. However, I can connect to it using 2 different private keys. One private key looks like this: -----BEGIN RSA PRIVATE KEY----- ...
44
votes
2answers
7k views

How can SSH server know private key is incorrect if passphrase havent been provided yet?

I have server which I am accessing via SSH. I only allow the authentication to be made with private key. Normally when I login via PuTTY, I am first asked for username and then asked for passphrase ...
0
votes
1answer
89 views

How do I determine if an existing SSH private key is secure?

For an ordinary user, how would I verify that a private key file was generated using reasonably secure algorithms? In response to things like allegedly insecure ssh-keygen defaults.
0
votes
1answer
68 views

What are the best ciphers in terms of performance for SSH tunnel?

From a security standpoint, there are few good cipher options to use with SSH, such as ChaCha20, AES 128/256 GCM/CTR. As I understand (please correct me if I wrong), all of these offer pretty strong ...
17
votes
3answers
4k views

Is ssh with public key authentication, no passwords secure enough?

I have a web server set up and would like to connect to it from outside using Tor. The web server simply serves up a simple webpage that will act as an interface for a program running on the machine. ...
3
votes
5answers
164 views

Difference between SSH Tunnel / Proxy and VPN in terms of security

What benefits does a VPN have over just using a regular SSH Tunnel? I'm considering setting up OpenVPN on a server, but was wondering what benefits that would have over just using that same server as ...
4
votes
1answer
124 views

If my private key is password protected, then how is it used without asking me for it?

Relating to TLS and SSH. If my private key is password / passphrase protected, how is this then used automatically during TLS or SSH communication without asking me for the password?
0
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0answers
19 views

Using the same private key for both WSL-Ansible and Putty (or WSL-OpenSSH for that matter)

I use Windows 10 home on my PC and SSHing to up to 5 Linux IaaS machines with either Debian/ArchLinux as server environments. I use Ansible to orchestrate and continuously integrate and continuously ...
1
vote
1answer
49 views

How does the public key get authenticated during an ssh session

When using SSH, my private key is stored on my computer safely and my public key is given to the other party I wish to communicate with. I understand that the two keys are mathematically related, and ...
0
votes
1answer
25 views

Is it worthwhile to restrict SSH on home web server to local network? [duplicate]

First, some background: I have a web server (Linux) which I run from my house. I have a relatively small website, and have just set up SSH. While modifying the firewall, I had the choice to pick ...
2
votes
1answer
56 views

Looking for SSH key management tricks that apply to a large fleet of machines to reduce the 'trust of first use' attack surface?

If you have too many machines and you are nearly always asked about a host key when you connect, it leaves an opening that the first time you connect to a machine it's a security threat, but anytime ...
3
votes
1answer
73 views

Why are passphrases protecting GPG / SSH private keys needed? [duplicate]

SSH and GPG each ask for passphrases during key generation. GPG also (at least from my experience) displays warnings if one is not provided and asks for confirmation that no security is indeed ...
1
vote
2answers
53 views

Possible to get sshd (openssh) to log the public key of failed key based login attempts?

As I understand sshd (openssh in my case) typically does/may log the fingerprint/hash of the public key of incoming connections which are attempting to authenticate via key. What I'm looking for is ...
0
votes
1answer
94 views

I think my raspberry was hacked, what should I do? [duplicate]

First of all, sorry if all of this seems a bit stupid, but my field of expertise is software development, not security. So, here is what happened. 1/ The breach I did something I really shouldn't ...
1
vote
0answers
19 views

Malware abusing SSH agent active keys

I am thinking about this lately a lot, so I wanted to get someone else's opinion. Let's say that I have an SSH key agent (e.g. Pageant or ssh-agent) running in background with loaded keys (keys were, ...
2
votes
2answers
114 views

How safe is it to allow key-based SSH access within LAN?

So this is my setup: We have a few machines in a LAN, used for computation, which me and my colleagues access from the outside with SSH. All our accounts on the LAN machines are managed and shared ...
1
vote
1answer
66 views

When first connecting via SSH to my server, the reported fingerprint does not match that given to me when I generated the SSH key

When I used ssh-genkey on macOS to generate the pair of key files (one named with .pub), that tool reported a SHA256 hash as a public key fingerprint. When first connecting to my server, a Digital ...
1
vote
2answers
45 views

Capture Response Attempting to Connect to Open SSH

I want to be able to attempt to connect to a host using password authentication and store the server's response in a variable. This is to see what hosts in my list accept passwords for their ssh ...
1
vote
1answer
87 views

Secure SSH host keys

I am trying to fix my SSH setup on Fedora and RedHat with ssh-audit. I managed to fix the ciphers and algorithms by setting KexAlgorithms diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,...
0
votes
1answer
45 views

SSH: Best practice for PublicKey Authentication from multiple Devices

I have a Server I want to access via ED2559 PublicKey Authentication. How would one do it so it is as safe as possible from multiple devices? Should I add multiple PublicKeys to my Server or should I ...
2
votes
1answer
896 views

How did a bug like CVE-2018-10933 (libssh authentication bypass) happen?

How did a bug like the recent libssh vulnerability come to exist? Exactly what is the nature and root cause of the bug? From libssh's website: libssh versions 0.6 and above have an authentication ...
70
votes
3answers
28k views

CVE-2018-10933 - Bypass SSH Authentication - libssh vulnerability

Looks like CVE-2018-10933 was just released today and you can find a summary here from libssh here Summary: libssh versions 0.6 and above have an authentication bypass vulnerability in the server ...
1
vote
1answer
127 views

SSH over VPN blocked on certain networks

Why can I only access protected resources over VPN on some networks? Location | SSH to GitHub | SSH to private IP ------------------|---------------|------------------- On-campus Wi-Fi | ...
2
votes
1answer
90 views

Honeypot SSH connection attempts with no interaction

I am seeing a lot (>50% of total events) of connection events on a honeypot I have set up but there is no further interaction, no brute force, just a connect then disconnect. I'm thinking this is ...
0
votes
1answer
72 views

Why are SQL servers not attacked as frequently as ssh servers?

I have a server running with both SSH and MySQL accessible to the public internet. Both run on default ports (22 and 3306). The ssh server is attacked by bots all the time. This is the output of ...
2
votes
0answers
53 views

Could a running SSH server somehow fool connected SSH client to create a reverse port forward?

Let's be extra paranoid and assume that the SSH server my client is connected to, was "enhanced" so that every SSH client that establishes an connection with it, will be tricked into thinking that it ...
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votes
2answers
158 views

End to end encryption in mobile banking? [closed]

Can we use E2EE to secure the communication between the bank and it's customers in the applications of mobile banking? And what is the status off E2EE vs SSH regarding this matter?
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2answers
303 views

Sending shutdown command via ssh using sudo non-interactively

With iOS 12 and the new Siri Shortcuts app, I've been thinking of ways I could leverage the SSH command capability in the app. For those of you who don't know, the app allows you to send a bash file ...
2
votes
2answers
137 views

Should I have an SSH bastion?

I am using AWS. I need to connect with a local SSH client to Linux EC2/ECS instances. I also need to connect with a local PostgreSQL client to RDS instances. There are tutorials for creating SSH ...
1
vote
1answer
167 views

VPN vs SSH tunnelling for hotel wifi

I know it's recommended to use a VPN with a hotel WiFi but if I'm in a hurry and don't have time to setup my own VPN server would an SSH tunnel (invoked with ssh -D) work just as well to secure my web ...
1
vote
1answer
70 views

Access from external network safely to raspberry

I am implementing a home alarm system with raspberry and I need to access it from the external network. The initial idea was to use cascade VPN and ssh (in my university to connect to the cluster I ...
2
votes
1answer
69 views

Can an old SSH session be reconstructed given root access to the server?

Say that A is behind a firewall that logs all packets, communicating with B over a publickey-authenticated SSH connection: A <-------- {ssh} --------> B v v [...
22
votes
2answers
4k views

Is telnet secure through SSH tunneling

Firstly sorry, maybe dumb question, but I have one service running on my server which can be operated only by telnet (port 23), but I know that telnet is insecure, so I blocked port 23 in iptables ...
6
votes
3answers
147 views

Is there any risk from attempting ssh authentication to a rogue server?

Suppose I'm about to connect to a new (unauthenticated to me) server. I've previously provided my ssh public key to the server owner (who populates it in the appropriate authorized_keys file). The ...
0
votes
1answer
42 views

How does Amazon Web Services generate SSH Keys?

How does Amazon Web Services generate SSH Keys? Does it generate the key pair completely in the browser or does it generate the keys in the server and send us the private key over HTTPS? I tried to ...
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votes
3answers
145 views

SSH into router [closed]

Is it possible to gain access to a router by SSHing into it. I understand that you can ssh into a specific server or machine with SSH, but can you do the same thing with a router if you know the ...
2
votes
2answers
130 views

Does using TLS, SSH and SSL in a connection makes it more secure?

If I use TLS as the protocol to send SSL encrypted packages through a SSH tunnel would this connection be safer than using any of the tools alone? ** EDIT ** Suppose I would TLS(SSL(SSH(data))) (...
2
votes
1answer
73 views

Is the same key used for Authorization and Encryption? (SSH Tunnel)

I am a bit confused on how SSH encryption works. From reading this question, I see you can use a private key to authenticate with the -i flag. I also know think that SSH encrypts data using ...
0
votes
0answers
121 views

Multiple sshd sessions for single SSH login

I was grepping through /var/log/auth.log and noticed that for some reason, not every time, but sometimes when I would log in via SSH I would see entries like the following - where there were multiple ...
1
vote
2answers
46 views

Automatic push on commit (on bitbucket repository)

I have a website which commits to a git local repository all the changes done. I need to automatically push them directly from the web server to a remote Bitbucket repository. The authentication ...
-1
votes
2answers
300 views

how to check if my server has been hacked [closed]

I have a couple of Ubuntu 16.04 servers. I want my server to be secure and ensure they can only be accessible by me and things. I check the auth.log and last. But I heard that hackers can change the ...
2
votes
0answers
87 views

yubikey creating different ssh public key having same GPG

I have 2 yubikeys and both are having the same GPG master key besides 3 subkeys for encrypting, signing and authentication, I can encrypt/decrypt and everything regarding gpg seems to be working fine, ...
3
votes
2answers
143 views

Is running an SSH tunnel from my Web App Server to my Database server safe security-wise?

I have a web app hosted in Digital Ocean and use Laravel Forge to keep a daemon running an SSH tunnel to another server (i.e. ssh -L XXX:127.0.0.1:XXX -p XXXX root@[ipaddress]). I do this in order to ...
4
votes
2answers
261 views

From FTP to SSH

Currently, I am doing a penetration testing laboratory with a server with the following services: Nmap scan report for 10.0.11.125 Host is up (1.3s latency). Not shown: 998 closed ports PORT STATE ...