sshd / ssh setup

Ken Stevenson ken at
Wed Feb 8 15:01:45 PST 2006

fbsd_user wrote:
> Have user who is logging in to USA site from Asian public internet
> cafes using his personal windows/xp notebook. Trying to setup the
> USA server and his windows/xp notebook to use SSH.
> Added sshd_enable="YES" to USA site server rc.conf and rebooted
> system.
> During boot process, followed sshd instruction and built
> the root user keys. Have read the handbook but have no clue as
> how to proceed. The handbook covers all the many different ssh
> config options, but does not say how to really use it.
There are a lot of options here, but here's how I do it. Not 
necessarily the best way, but it works for me.

> Need procedures to
> 1. setup users on FreeBSD target sshd server.
Create a regular login for each outside user using adduser.
Make sure port 22tcp is open inbound.

Login as that user and run:

ssh-keygen -t rsa

I don't have many users so I disable ChallengeResponse authentication 
and require users to submit keys. To do that, edit 
/etc/ssh/sshd_config and set:

ChallengeResponse no

I also set:

Protocol 2

> 2. setup users on FreeBSD remote box to ssh to sshd server.

Have them run the same ssh-keygen -t rsa

Tell them to send you ~/.ssh/

Concatenate that to the ~/.ssh/authorized_keys2 files in their home 
directory on your server. Make sure the key ends up on a new line in 
authorized_keys2. If there wasn't a newline at the end of the file 
previously, it will end up concatenating it to the end of whatever 
keys are already there. If that happens, just go in with a text editor 
and break the line.

The user should then be able to ssh into your box.

> 3. setup users on windows/xp remote box to ssh to sshd server.

Install Putty

Run puttygen and generate an SSH2 RSA key (select this at the bottom 
of the dialog box). Tell them to save the public and private keys, and 
then to copy the contents of the Public key for pasting.. field at the 
top of the screen, paste it into a file in notepad, and email it to 
you. Concatenate that to the end of their ~/.ssh/authorized_keys2 file 
as you did for your freebsd users.

If they're going to be logging in often, tell them to run pageant to 
cache the private key.

Then they can run putty and connect to your server.

Again, you might not want to do it this way if you don't want to mess 
around with having users send you keys, but it's a lot more secure. 
Pretty soon you'll be be getting a 100 or more hits a day from 
crackers trying to log into your system. They'll never get anywhere if 
  you're using key based authentication.
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Ken Stevenson
Allen-Myland Inc.

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