Ubuntu Security :: Single Use SSH-RSA Keys?
Jul 20, 2011
My primary Ubuntu server has SSH exposed to the internet so I can remotely access it. I have configured OpenSSH to use only RSA key authentication. Each computer I use has a separate RSA key unique to it. I also have a unique RSA key on a USB thumb-drive I carry with me. The purpose of the USB key is for emergencies if I have to access the server from some remote system. The problem is that I may not trust the remote machine (university/public library computer for example).
What I would like to do is have a set of one-time use RSA keys that, after I log in to SSH with them, are removed from the authorized_keys file. This would hopefully keep my system safe even if the remote machine I was using was compromised and had copied my private key and key-logged the password I used to decrypt it. I would like to have these keys be separate from the keys I have for my trusted computers.
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Jun 7, 2011
I am not very security minded...I'm aware of it, and always made sure I had up-to-date overall protection in Windows but firewalls, and the blasted passwords are largely a thorn in my side!When I got my iPhone last year I suddenly discovered password managers & "wallets" to keep all that kind of information in and syncable across different devices. My life got so much easier. Of course now I need to figure out encryption keys, and how they work (I'm clueless). I also need to find a program or system that I can move my existing low-tech info (mailnly user name & passwords) that will also accomodate the increased needs of Ubuntu security and still be sync-able. I started a little research weeks ago, but my current "wallet" only exports .csv so I quit since I'm going to have to do a lot of data entry whatever I go with.So here goes:
1) what is the difference (bare bones) between using an encryption key (e.k.) vs. a standard user created password? what situations are better suited for e.k.?
2) I have seahorse (default intall with Ubuntu I guess) but the only thing in it is Login under passwords which leads to a login keyring (?) and a drop-down list of about 6-10 of the gazillon passwords I use daily. The other tabs are for keys which I don't have any concept of.
3) I know FF also "remembers" user id & passwords as you choose to have it do so. Is that information transferable into seahorse or another program?
4)I'm also (today) getting ready to really set up my system for user names & security across my little home network. How can I integrate that into whichever program/app I go with to store my pwds and keys?
5)give me links to fairly current documentation on this stuff?
6) Any program/app recommendations.Pros/cons uses, what they can & can't do or be used for, etc.
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Jan 2, 2010
Im a total beginner when it comes cryptography and networking. Finally managed to create a connection with OpenVPN on Ubuntu to a vpn provider called ivacy. On this page:http://ivacy.com/en/doc/user/setup/winxp_openvpn they give configuration files and keys, which I used. The question is, if someone wanted to see my network traffic, could they do it using the keys provided on that page. Reading the OpenVPN documentation i saw that it is also possible to create your own keys. Would that be more secure?
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Jan 13, 2010
I have generated SSH *.pub and *.ppk keys.
Where should I put them so that they are automatically used and available when e.g. issuing an ssh ....
command in Terminal?
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Feb 6, 2010
I'm having trouble logging in with SSH using RSA keys.
client: Karmic
server: FreeNAS (FreeBSD) ip: 192.168.0.100
I generated RSA keys on Karmic, added the id_rsa.pub to the authorized_keys file on FreeNAS, then removed the id_rsa.pub from Karmic (this is a poorly documented but necessary step I learned).My Karmic username is shawn, FreeNAS username is shawnboy.from Karmic it prompts me for my RSA key passphrase which it should do, but after I enter it, it fails and moves on to prompt me for my password. I know this isn't a FreeNAS forum, but this works perfectly using Putty SSH with RSA keys on Windows XP, so I figure it's more appropriate to ask here than in FreeNAS forums.
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Feb 9, 2010
Short description of the difference between GPG and SSH keys?
Also, is it possible to combine the two keys? Meaning I can just use one key for both applications?
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Sep 29, 2010
Scenario 1. I am doing this from /home/deploy directory I am trying to set up ssh with github for capistrano deployment. this has been an absolute nightmare. when I do ssh git@github.com as the deploy account I get Permission denied (publickey). so may be the key is not being found, so If I do a ssh-add /home/deploy/.ssh/id_rsa Could not open a connection to your authentication agent. (i did verify that the ssh-agent was running) If I do exec ssh-agent bash and then repeat the ssh-add then the key does get added and I can ssh into github. Now I exit from the ssh connection to my server and ssh back in and I can't ssh into github anymore! Scenario 2 if I login to my remote server and then cd into my .ssh directory and ssh into github then it all works fine I guess there is a problem with locating the key and for some reason the agent isn't funcitoning correctly.
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Feb 11, 2010
I have enabled ssh key based logins for one of my servers and disabled normal password based logins. It just occurred to me that the public key which I generated on my pc, and uploaded to the servers authorized_keys, may in fact only apply to my local PC / user account. So basically if my system crashes I would have no way to login to the server...? Is it not possible to "share" public keys so other people (PCs / accounts) can use them?
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Feb 19, 2010
I've installed the ssh server on my Ubuntu desktop and the very first time I accessed the server from my laptop, it got a message asking me whether to permanently add the key of the server. After I added this, it gave me a message saying that the key had been permanently added. My question is how do I remove this key? I just want to know how to do this because I'm going to disable password based logins and I want to start anew.
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Jun 1, 2010
What is the easiest way to encrypt plain text content with a password only? I need to encrypt client login information, but I hate dealing with all the unnecessary complexities of Linux's encryption systems.
I know I am going to get a bunch of people telling me how perfect Seahorse and whatever is, but Seahorse and the default /home directly encryption have both given me too many problems when decrypting my information. I prefer to preserve my data rather than using these methods.
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Aug 25, 2010
Can i login to my server using my root account and create a public+private key for one of my users and then manually paste it into his authorized_keys file and give him the private key?
The user im giving it to has a chrooted FTP account...
Is it still ok that i used the root account to create it? He is not going to have root access or nothing is he? This is not a security breach in any way is it?
The user doesn't have shell access to create their own so this is the only way i can think of doing it...
Also what access should the user have to their .ssh folder + the authorized_keys file...?
Are they allowed to read the key? What about write?
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Sep 8, 2010
I recently upgraded to Ubuntu 10.04. I love the passwords and keys application, but was somewhat surprised at the lack of a context menu in gnome to encrypt a file.
In general, I cannot find how to encrypt files using the keys I generate. Maybe I'm missing something? Probably, I just thought since Ubuntu comes with OOB key generation it would have OOB encryption capabilities.
I've read about seahorse and other ways to ADD encryption, I'm just wondering if ubuntu does it natively. It'd be a good idea to add to brainstorms, right click and encrypt.
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Jan 30, 2011
Ubuntu 10.10 Server is loaded. Openssh has been loaded.
I have multiple users which need access to server via ssh.
My impression from reading about ssh is that a key needs generated for each person. Thus, each key will have a passphrase that is unique to them.
In /etc/ssh/sshd_config, the default sshd_config suggest using:
%h/.ssh/authorized_keys
My assumption is %h is a variable that will allow the current user to use the public key stored in his home directory under the .ssh folder in a file called authorized_keys. Is their a command string that automatically populates the authorized_keys file?
I am surprised that even though there are a number of hidden (e.g. .****) files located in the home folder, there is not one automatically generated as .ssh. It appears I have to create that directory myself. I am especially surprised by this since it appears the instructions for generating a key seems to load the key in the home directory instead of proceeding to create a .ssh folder to store the keys in.
It is not clear, but it appears that the public key needs to be copied or appended to the authorized_keys file, but, using the scheme above, the public key needs to be copied or appended to each users authorized_keys file instead of appending all public keys to a single authorized_keys location.
It then appears that each persons authorized_keys file needs permissions set to 600.
It also appears that if I decide to use RSA instead of DSA, I would do the same thing above but would use authorized_keys2 file instead.
Why doesn't the home folder which gets automatically set up for each user automatically get a .ssh folder generated? i.e Why does it have to be created by hand? Does it need the same permission on the .ssh folder? ie 600?
My aim is to allow many to log on via ssh simultaneously and then allow many to simultaneously vnc into their respective gnome desktops.
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Mar 11, 2011
How can I configure my SSH server (OpenSSH on Debian 5) so that it requires public key authentication *and that the keys are password protected*?
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Mar 26, 2010
At the moment we have one SSH server with the private key being on a usb flash drive, and the public key being on the server in authorized_keys2. Now that three more servers are coming online, should we generate new keys, so we have muliple private and public keys (one pair for each server), or use the same two keys to access all the servers
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Mar 31, 2010
I am using Nautilus to connect to an external server. Currently, I use password authentication, and all works fine. I just type sftp://SERVER and the connection is established after providing the login credentials. However, I changed the server to only accept Public Key Authentication and disabled password authentication, and as a consequence I could not login using Nautilus anymore. Is there some way to make this work?
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Sep 22, 2010
I want to block some ips permanently ie. even I as the root user cannot unblock these ips without having to format the whole system.
So i thought if some blocking software provided passwords for editing rules and I put a 'junk' password there and so that I can't delete the rules without the 'junk' password which I don't know.
So I examined iptables and I saw that it is a kernel module so there is no use of that since I can probably throw it away.
But the basic question is to block ips and gulp the key.
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Mar 28, 2010
Since reinstalling Ubuntu 9.10 and learning how to get the Notification Area working properly:
I've noticed an bunch-of-keys icon appearing intermittently in my notification area.
It appeared about 20 mins ago. I hovered the mouse over it and it generated the following text:
"Click on the icon to drop all elevated privileges"
I right-clicked on the icon, thinking I might learn something more about it. But it disappeared. No other messages were given.
It appeared again about five or ten minutes ago. I did not click on it. But it disappeared of its own accord after a minute or two.
What is this? Should I have clicked on it? What have I done? How can I get this bunch of keys under my control?
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Jul 5, 2010
Since I have installed Fedora 13 it seems that I can't connect to WLAN APs which aren't secured by WPA. I'm surprised about the inserts to the messages logfile:
[Code]...
Most surprising insert for me: Jul 5 20:43:21 nbtobiaslnx NetworkManager[1328]: <info> Config: added 'key_mgmt' value 'WPA-PSK' Is this the reason for my problem? I use KDE and Network Manager for managing my networkconnections.
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Mar 16, 2011
I am trying to lock down a server using audit.rules. I intend to use ausearch to review certain entries from time to time. I noticed that it's possible to assign a "key" to each rule and then use `ausearch -k` to show only the records that have that key.Unfortunately, the key feature seems broken. I started with the following rule in audit.rules:
Code:
-a always,exit -F arch=b64 -S open -S openat -F exit=-EACCES -k deny
I do a `cat /etc/shadow` and a `ausearch -ts today -k deny` and it seems all went well.
[code]....
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Dec 19, 2010
When a user that has rsa public key set in ~/.ssh/authorized_keys file logs in via ssh an sshd process is started to handle the ssh session.Periodically we audit the authorized keys and remove them from the system and authorized_keys file. This means the next log in attempt will fail, which is fine.However we need to terminate current ssh sessions in progress that use the rsa key.I have not been able to determine a way to map sshd processes with authorized_keys entries.
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Mar 6, 2010
I'm wondering if anyone can give me some guidance, or point me to a relevant reference for setting up a single purpose ssh key.I have setup a single purpose key for rsync, where I have command="/path/to/rsync-secure" associated with the public key in .ssh/authorized_keys, and the rsync-script checks to make sure incoming commands begin with 'rsync --secure', What I would like to do is do something similar to allow sshfs access, and have the server path that can be mounted locked down to a particular location. Does anyone have any suggestions as to how this could be done?As an aside, I might also want to restrict the above rsync script to only allow synchronization to a particular path.
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Sep 1, 2011
I have ubuntu 11.04 installed along side windows. And I often share files with windows computers. If I am installing a new package from ubuntu software center, and consquently I have to log in as root to do so, which means I have given the system 'privileges' as the program is being installed, I decide to go open mozilla, and surf suspicious sites on the net. Is it possible in that case for me to get a virus?
When we enter the password for the root user in order to run one program such as ubuntu software center, does that mean that all programs have root privileges for the time being (as the software center is installing the program)?
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Oct 20, 2010
Ive been running ssh to log into server for long time. Recently a x-win app reported that it suspects a man in the middle attack (MiMA), so I want to tighten this up, but it seems to me if there is a MiM, then the initial key exchange is vulnerable to a substitution. This is on solaris, but since its a basic concept I'm ot getting, it shouldnt matter,
Here's the gist of what I read:
- create users key pair,
- enable host authentication (ssh_config file on client and sshd_config file on remote host)
- start an ssh session and accept the remote hosts key (and I assume the remote host will take client users key and store some where)
Questions:
1. What's to stop the MIM from making a substitution of keys during the initial exchange?? Shouldn't the keys be initially transfered in a more secure fashion??
2. Does the server just accept new keys from any existing user who want to create an ssh session? So if some one knows a username and password (such as the owner of an application they know is running) couldn't they just create their own keypair and have the server accept them?
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Feb 26, 2010
Is it possible to restrict root logons to the SSH server to just a single ip address (or maybe a range?) I have other users connecting to the server daily so restricting ALL access to a single ip i cannot do. I need root enabled (for my own reasons) but want to lock it down a bit more.
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Mar 25, 2010
I was wondering whether or not it is possible/advisable to install and run Snort on a single laptop with a wireless router (firewall enabled)? Does Snort require root privileges and are there any other issues one needs to be aware of when installing and running software like this?
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Apr 3, 2010
Is there a program that allows me to password lock a single file or folder?
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Jun 20, 2010
I am running Fedora 13 - 64-bit variety and using KDE as the gui. No real issues asides from machine not exactly flying, but then this is a mere core 2 duo 1.6 with 2 gigs of ram, so not unexpected...
When I run top I see 3 users indicated - which worries me somewhat... I am the only user on this machine.
I come from a Debian / Ubuntu /Gentoo knowledge-base and this laptop is a fresh install, encrypted partitions, temp has own partition (encrypted too) and obviously the firewall is on, with ssh service turned off and ssh access removed in the firewall....
is this 3 users in top normal, or have i managed to be hacked in the 3 - 4 days since I started the install ? In all this time I have been sitting behind a router when on the net.
Am I looking at a fresh install, or are there valid reasons for the extra users?
I just ran "users" in terminal and I show up 3 times - I have only logged in once, through the GUI and no extra access routes
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Sep 5, 2010
How to number of connections for a single ip on port 80 to CentOS 5.5 with iptables? connlimit did not work on CentOS and nginx does not provide a module for that
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Jun 27, 2011
Just wondering if Ubuntu has an Accessibility equivalent for sticky keys and mouse keys.
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