Comments on: Installing and Using a SSH Server http://tombuntu.com/index.php/2008/02/19/installing-and-using-a-ssh-server/ News, Tips, and How-Tos for Ubuntu Linux Thu, 02 Sep 2010 12:08:33 +0000 http://wordpress.org/?v=2.9.2 hourly 1 By: aikonbrasil http://tombuntu.com/index.php/2008/02/19/installing-and-using-a-ssh-server/#comment-81644 aikonbrasil Mon, 08 Mar 2010 23:44:41 +0000 http://tombuntu.com/index.php/2008/02/19/installing-and-using-a-ssh-server/#comment-81644 An Excellent Post, Congratulation !!!!!!!! I will be visiting your blog all the time. Thanks. An Excellent Post, Congratulation !!!!!!!!

I will be visiting your blog all the time.

Thanks.

]]> By: Jaun Millalonco http://tombuntu.com/index.php/2008/02/19/installing-and-using-a-ssh-server/#comment-63163 Jaun Millalonco Wed, 01 Jul 2009 19:03:25 +0000 http://tombuntu.com/index.php/2008/02/19/installing-and-using-a-ssh-server/#comment-63163 My first visit here, found the blog accidentally really, and I just wanted to say I've enjoyed my visit and had some good reads while here :) Juan My first visit here, found the blog accidentally really, and I just wanted to say I’ve enjoyed my visit and had some good reads while here :)
Juan

]]> By: analog_G http://tombuntu.com/index.php/2008/02/19/installing-and-using-a-ssh-server/#comment-8384 analog_G Fri, 29 Feb 2008 18:21:59 +0000 http://tombuntu.com/index.php/2008/02/19/installing-and-using-a-ssh-server/#comment-8384 Great post. So simple I was able to call my wife from work and she installed openSSH from a command prompt. I am now using PuTTY.exe on my Windows machine at work to connect (SSH) to my Linux Machine at home. I just modified my sshd_config file remotely to only allow me as an openSSH user. Cool stuff. Great post. So simple I was able to call my wife from work and she installed openSSH from a command prompt. I am now using PuTTY.exe on my Windows machine at work to connect (SSH) to my Linux Machine at home. I just modified my sshd_config file remotely to only allow me as an openSSH user. Cool stuff.

]]> By: Ram http://tombuntu.com/index.php/2008/02/19/installing-and-using-a-ssh-server/#comment-8289 Ram Thu, 28 Feb 2008 10:56:46 +0000 http://tombuntu.com/index.php/2008/02/19/installing-and-using-a-ssh-server/#comment-8289 Wonderful post bro. Simple n clear explanation. Wonderful post bro. Simple n clear explanation.

]]> By: db0 http://tombuntu.com/index.php/2008/02/19/installing-and-using-a-ssh-server/#comment-8024 db0 Sun, 24 Feb 2008 18:16:57 +0000 http://tombuntu.com/index.php/2008/02/19/installing-and-using-a-ssh-server/#comment-8024 Excellent post. This is exactly what I needed to administer my girlfriends computer without asking for a rdc connection every time :) Cheers! Excellent post. This is exactly what I needed to administer my girlfriends computer without asking for a rdc connection every time :)

Cheers!

]]> By: Tom http://tombuntu.com/index.php/2008/02/19/installing-and-using-a-ssh-server/#comment-7741 Tom Wed, 20 Feb 2008 06:24:45 +0000 http://tombuntu.com/index.php/2008/02/19/installing-and-using-a-ssh-server/#comment-7741 Jonas: Thanks for the tip on changing the port in ssh_config. Tony: Public key authentication is tomorrow's post :) Jonas:
Thanks for the tip on changing the port in ssh_config.

Tony:
Public key authentication is tomorrow’s post :)

]]> By: Jonas http://tombuntu.com/index.php/2008/02/19/installing-and-using-a-ssh-server/#comment-7728 Jonas Wed, 20 Feb 2008 02:37:17 +0000 http://tombuntu.com/index.php/2008/02/19/installing-and-using-a-ssh-server/#comment-7728 Quick-and-dirty, and assuming it is your server so you have root-access to it. On the server, Make sure you have the following in /etc/ssh/sshd_config: PubkeyAuthentication yes PasswordAuthentication no On the client, do: 1. ssh-keygen -t rsa (up to you if you want to use a pass-phrase or not. As long as you keep the key-files secured, it is more convenient without one). 2. ssh-copy-id -i ~/.ssh/id_rsa.pub username@server (this copies the pub-key to the server) Finally, you should be able to do ssh server. The first time you will get a warning, and then you will be asked about your pass-phrase if you created one. Otherwise, you should be let in. This assumes that you have the same username (and the same UID and GID) on both the client and the server though. Finally, as root on the server /etc/init.d/ssh restart Note though that I would recommend to NOT turn off password authenciation until you know the pubkey setup works... Now, if you followed the suggestions to make sure only trusted users are allowed to use ssh and changing the portnumber, a potential hacker would need: 1. To find out the correct portnumber. 2. Find the correct username 3. Get access to your keyfile somehow. Note too that if you just want to use this on a server that you do not have root access to, it should work too except that you of course have to rely on the server being properly set up in the first place (or pester the administrator to set it up for you...). If it allows ssh-logins, I would hope that it is. Quick-and-dirty, and assuming it is your server so you have root-access to it.

On the server,

Make sure you have the following in /etc/ssh/sshd_config:

PubkeyAuthentication yes
PasswordAuthentication no

On the client, do:

1. ssh-keygen -t rsa (up to you if you want to use a pass-phrase or not. As long as you keep the key-files secured, it is more convenient without one).
2. ssh-copy-id -i ~/.ssh/id_rsa.pub username@server (this copies the pub-key to the server)

Finally, you should be able to do ssh server. The first time you will get a warning, and then you will be asked about your pass-phrase if you created one. Otherwise, you should be let in. This assumes that you have the same username (and the same UID and GID) on both the client and the server though.

Finally, as root on the server /etc/init.d/ssh restart

Note though that I would recommend to NOT turn off password authenciation until you know the pubkey setup works…

Now, if you followed the suggestions to make sure only trusted users are allowed to use ssh and changing the portnumber, a potential hacker would need:

1. To find out the correct portnumber.
2. Find the correct username
3. Get access to your keyfile somehow.

Note too that if you just want to use this on a server that you do not have root access to, it should work too except that you of course have to rely on the server being properly set up in the first place (or pester the administrator to set it up for you…). If it allows ssh-logins, I would hope that it is.

]]> By: Tony http://tombuntu.com/index.php/2008/02/19/installing-and-using-a-ssh-server/#comment-7716 Tony Tue, 19 Feb 2008 22:56:45 +0000 http://tombuntu.com/index.php/2008/02/19/installing-and-using-a-ssh-server/#comment-7716 Wonderfully informative post. Can you explain how to use public key authentication? Wonderfully informative post.
Can you explain how to use public key authentication?

]]> By: Jonas http://tombuntu.com/index.php/2008/02/19/installing-and-using-a-ssh-server/#comment-7699 Jonas Tue, 19 Feb 2008 18:15:26 +0000 http://tombuntu.com/index.php/2008/02/19/installing-and-using-a-ssh-server/#comment-7699 I think you missed one important aspect in securing a ssh-server: don't allow people (even if it's just yourself) to connect to it using passwords. Do it using public key authenciation, and brute force password crackers will work in vain. Of course, using public keys provide an additional bonus apart from better security. It makes using sshfs more convenient in that you can mount a ssh directory without being prompted for a password or passphrase at boot-time, especially convenient if you mount them using fstab. And speaking of convenient...since you mentioned changing the port of the server you might want to change the corresponding part of the client ssh_config file. Just so you don't have to remember adding the -p 2222 every time. I think you missed one important aspect in securing a ssh-server: don’t allow people (even if it’s just yourself) to connect to it using passwords. Do it using public key authenciation, and brute force password crackers will work in vain.

Of course, using public keys provide an additional bonus apart from better security. It makes using sshfs more convenient in that you can mount a ssh directory without being prompted for a password or passphrase at boot-time, especially convenient if you mount them using fstab.

And speaking of convenient…since you mentioned changing the port of the server you might want to change the corresponding part of the client ssh_config file. Just so you don’t have to remember adding the -p 2222 every time.

]]> By: Fer http://tombuntu.com/index.php/2008/02/19/installing-and-using-a-ssh-server/#comment-7696 Fer Tue, 19 Feb 2008 17:26:36 +0000 http://tombuntu.com/index.php/2008/02/19/installing-and-using-a-ssh-server/#comment-7696 Nice! Cheers from Barcelona, Spain Nice!

Cheers from Barcelona, Spain

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