Tagged Questions

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

learn more… | top users | synonyms

2
votes
1answer
213 views

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, ...
3
votes
1answer
183 views

find passphrase on encrypted ssh private key

I have an openssh encrypted private key. I don't remember the pass-phrase. I may be able to suggest words or patterns that may be in the phrase. I am looking for software that will help me recover ...
0
votes
0answers
17 views

Is Mosh as secure as SSH? [duplicate]

Mosh, from my limited understanding of it, is a service which operates a shell over UDP. It claims to use SSH to initiate the connection, then starts the Mosh service on the client, and then connects ...
-1
votes
2answers
103 views

Should I use more than 2048 bits in my SSH-2 RAS 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?
0
votes
2answers
316 views

Given an IP address can you ssh into /tmp without password?

I'm a Software Engineer, but I have no experience in security, so i'm trying to learn by doing (woot Experiential learning!). I know that the permission settings on the tmp folder are very relaxed. ...
0
votes
2answers
110 views

Can a SSH server or client to initiate a unencrypted connection?

Several clarifying questions: Is it possible to disable the SSH encryption using options at the OpenSSH server/client or some appropriate hack? Is it possible to do this at the time of the ...
1
vote
2answers
49 views

can ssh port forwarding be detected?

say there are three players: A, B, C where A is local machine, B is ssh server, C is the final destination. through ssh local port forwarding, A can connect to C via B. So then data will be ...
1
vote
1answer
41 views

what is a server fingerprint in ssh?

Is is the same as a public key in RSA, except they made it more suitable for self-signed hosts? What happens behind the scenes when our ssh client presents it to us?
1
vote
2answers
71 views

Risk in connecting wrong ssh host?

I've a ssh host key login setup in a remote server, for some reason, the DNS of that host is mapped to another server. So assume the mistaken host cannot be trusted, should I change my key?
0
votes
1answer
61 views

unfamiliar IP when logging into ssh server

I just noticed something today, and Now I am curious... I was on my shell server, an i was wondering who was on, so I gave the command $w and saw this: j0h@server:~$ w 22:06:02 up 18 days, 7:02, ...
5
votes
1answer
247 views

Can an SSH server fingerprint be spoofed?

If I simply connect to an SSH server, get its key fingerprint, and immediately disconnect, does the SSH protocol ensure that the server also had the private key in order to get that far into the ...
2
votes
1answer
90 views

Practical advantage of requiring VPN for SSH

I have some VPS servers which I manage through ssh. However there are many ports which I want open during development, therefore I also have OpenVPN on them. Now I am wondering if it would make ...
0
votes
2answers
269 views

Encrypted offsite storage using sshfs and cryptsetup/dm-crypt/LUKS

I'm interested in an encrypted offsite storage scheme, but I don't want to depend on the vendor for encryption. I have an idea for doing so by combining sshfs with cryptsetup/dm-crypt/LUKS, but I'd ...
1
vote
2answers
246 views

Storing SSH private keys on an Android device

(I'm not sure if this better belongs on unix.se or android.se, but since it's primarily security-related, I'm asking it here) I use my Android device to access servers for quick on-the-go ...
0
votes
2answers
213 views

Checking if a server is compromised

I do free/low-cost web/shell hosting as a non-profit organization (With a the same friend and co-founder) since 2007. We're on CentOS 6 + CPanel, and unfortunately we're still funding the ...
4
votes
1answer
117 views

Does SSH authorized_keys violate the principle of “re-authenticate before password change”?

It is generally accepted that password change mechanisms should ask the user for their old password (e.g. OWASP) The reason being that an attacker who has temporary access to a user's session (be it ...
10
votes
2answers
561 views

SSH connection attempts from China show different key; is China doing a MITM attack on SSH traffic?

I have a server located in the USA and SSH to it from various places around the world. When I SSH in from a computer I have never used before, I'll see something like this: The authenticity of host ...
4
votes
2answers
343 views

In there any point in passphrase-protecting an SSH private key that is used by a service account?

On my Linux machine (Alice), I am setting up a service account with an rsync cron job that will synchronise some files with a remote host (Bob). Obviously, I would want to make the rsync secure by ...
1
vote
1answer
794 views

Bypassing CVE-2010-4478 (J-PAKE parameter validation) in OpenSSH 5.1

Did anyone successfully exploit CVE-2010-4478 in the past? This is insufficient validation of the J-PAKE public key parameters in OpenSSH up to 5.6. I'm dealing with a vulnerable machine running ...
1
vote
1answer
52 views

Should statically-linked server binaries (daemons) be deemed more secure? [closed]

For a long time I've pondered this question. I am aware of the benefits and downsides of dynamic libraries (shared objects), including the infamous article by Drepper. All other things being equal, ...
0
votes
0answers
56 views

My server has been brute forced what now? [duplicate]

I have installed a raspberry pi for fun at home. I opened the port 22 and this morning I was concerned about someone brute forcing my server. I ran this query : cd /var/log;zgrep ssh auth*|grep ...
3
votes
1answer
462 views

Open source solution to capture and decrypt SSH traffic (with private key)?

I am looking for a free open source solution that is able to capture and decrypt SSH traffic given the fact that I can provide the server's RSA private key (something like SSH CryptoAuditor). Please ...
0
votes
1answer
229 views

How compromised should I assume my computer is?

I had turned ssh on a while ago to do some remote work. I was just looking over some netstat info when I noticed someone had established an ssh session with me D: I turned ssh off immediately and ...
1
vote
1answer
74 views

Simple way to protect ssh against man-in-the-middle attack? [duplicate]

If a narrow, trusted channel is needed (for example, there is an usb key to take data between the machines), it is okay. Although SSH will throw a big error if it tries to connect to a server ...
26
votes
1answer
3k views

Is all data sent over SSH encrypted?

When you are connected to another computer over SSH, is all data transferred between the two computers encrypted? Or is any data sent in plaintext or any other "easy to intercept" format?
3
votes
3answers
104 views

What benefit is there to adding a password to your SSH key?

If you run the following command on a Linux/Unix machine, among other things, you get a prompt for a password: $ ssh-keygen -t dsa Enter passphrase (empty for no passphrase): What does adding a ...
6
votes
4answers
427 views

Is it secure to use *no authentication* for services listening only on localhost?

I have many applications installed on my server that use a webui frontend to control the application. Since I am the only user of the server, I usually bind these applications to 127.0.0.1. As the ...
3
votes
2answers
117 views

security via chsh

I am developing a program that I want people to be able to connect to and use via ssh. I've decided a simple way of doing this would be to create an account for them on my linux server, and change ...
3
votes
1answer
164 views

SSH MITM attack underway

UPDATE: The source of this problem has thankfully turned out to be a buggy mobile SSH client used on 2 different devices not a MITM attack. However, I'd still appreciate a full answer to the original ...
2
votes
2answers
235 views

Is HTTPS as secure or more secure than SSH if both have an IP address whitelist?

I'm wondering whether an HTTPS API endpoint would be as secure as or more secure than SSH. API Endpoint The API endpoint would require HTTPS The API authentication would use a POST'd API key. The ...
1
vote
0answers
174 views

SSH PermitLocalCommand Security

After a quick search, I haven't been able to find lay risk assessments of the PermitLocalCommand option in ssh. Are there known vulnerabilities that allow arbitrary code execution on the local host ...
0
votes
0answers
40 views

Pwn Plug like tunneling suite

Is there some sort of a (free) SSH tunneling suite like the one on the Pwnie Express' Pwn Plug (R2)? It has SSH over HTTP, DNS, ICMP, and other covert tunneling options and uses BackTrack 5 as a SSH ...
0
votes
2answers
132 views

Creating port-specific SSH authentication for the same user

I have a Linux server running SSHD and would like to know if its possible to configure it, such that from within the LAN you only need a RSA key to authenticate (on port X), but from outside the LAN ...
0
votes
3answers
51 views

Restrict access to admin area by checking SSH connections

Assuming that the users have dynamic IPs (so I can't whitelist) and that setting up a VPN is not an option, is it a valid approach to restrict access to an administration area by only allowing IPs ...
1
vote
0answers
106 views

SSH using pre-existing session (symmetric) keys

Is there at present a way to open a SSH connection using pre-existing symmetric session keys? In other words, if I create a list of symmetric keys can I send that list to the recipient on a CD or USB ...
5
votes
3answers
246 views

Is it a bad idea to share the ssh host key in a diskless environment?

I am looking at this cluster of student work stations. They are diskless clients which boot from NFS. They also have sshd enabled. All of these machines share the same ssh host key (rsa,dsa,etc), ...
0
votes
0answers
65 views

Central Authentication Server

I have many client devices that I need to reverse SSH tunnel into. I am finding that managing all these certificate files are becoming cumbersome. I am looking into a centralized authentication ...
1
vote
1answer
374 views

Digital Ocean “Droplet” allgedly compromised for trivial, unpublicized website. Should I be worried abouty my own machine?

I got a message from D.O. about my Droplet saying they shut it down because there was a lot of outgoing traffic that looked like an attack. The site I had on that server was not very known at all. ...
2
votes
3answers
264 views

I want to roll my personal cloud hosted Password Manager using pass. How secure/insecure would this be?

I've come to the conclusion that I need to up my security. I currently have a dozen memorized passwords I use for every device and website. I'm against Keypass/Lastpass due to having to trust they ...
-4
votes
1answer
134 views

Most secure SSH server [closed]

Which SSH server (compatible with Debian Wheezy) has the fewest (if any) exploitable security bugs?
0
votes
1answer
1k views

Use SSH config file with Putty [closed]

I'm using SourceTree (a Git GUI) which uses PuTTY as SSH client. I need to push some code into a repository for which I need to tunnel through SSH to do so. The trouble is, the repository and SSH ...
7
votes
1answer
229 views

SSH: benefits of using hashed known_hosts

What are the benefits of storing known_hosts in a hashed form? From what I read, it is supposed to protect the list of servers I am connecting to, presumably in a scenario where my account has been ...
0
votes
1answer
152 views

Python SSH vs SSL? [duplicate]

I read the What is the difference between SSL vs SSH? Which is more secure? , and it mentions there is the possibility they can be affected by similar attacks. Now that the heartbleed thing is out, ...
0
votes
1answer
195 views

Outbound Port 443 Open but Not Allowing SSH [closed]

My college wireless network has a firewall blocking all outbound ports except 443 and 80. The wired network, however, has none of these restrictions. I can connect to HTTPS sites (obviously). On my ...
7
votes
2answers
536 views

How are two systems able to set up a secure SSH tunnel over a public connection?

As I understand it, when two systems create a secure SSH tunnel, the first step involves communicating the 'guidelines' for the encryption of that tunnel. If an third system is able to listen in on ...
4
votes
3answers
4k views

How does SFTP function without a manually generated public/private key pair

I am learning about SSH and how to use it to secure file transfers and commands between a windows machine and a Linux server. Everything that I have read so far indicates that I need to use an SFTP ...
1
vote
0answers
50 views

Considerations when implementing a key based SSH-like auth scheme

I have a SMTP server where all the users (for an unrelated reason) will have public keys tied to their username and registered with the server. I want to add a non-standard extension that uses these ...
2
votes
1answer
139 views

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

Is it possible to use running SSH agent to decrypt some data (supplied as a string or read from file)?
5
votes
2answers
476 views

How secure is OpenSSH on FreeBSD?

In a discussion about the recent OpenSSL information disclosure vulnerability, the subject of OpenSSH being vulnerable came up. While OpenSSH is not vulnerable due to the problem lying in the TLS ...
6
votes
1answer
368 views

Harden a server against mass SSH DoS attacks

How can a Linux server be protected against an attacker that tries to open a large number of SSH sessions (probably trying to brute force a password) that no ports remain to be able to legitimately ...