With this command:
ssh git#<my git server>
I can get a nice listing of my access privileges, i.e.
#R #W some_branch
#R some_other_branch
Is there a way I can get a similar listing for another gitolite user, even if I don't have access to that user's private key?
You would need to modify the src/commands/info file, in order to get the output you want.
That ssh git#server info command only takes a <repo name pattern> as an argument.
Related
I have a PHP application, with Usernames and Public SSH Keys in it. I would like to use these accounts as the user back end of openssh.
I think I need to use pam_exec and a PHP/Bash script. I've written a php script that I can execute at CLI (The shebang sets an env of php executable). If I need to wrap this in a bash script instead to access environment variables I can do that. The script currently takes a username as its first and only parameter like so:
/opt/scripts/my-auth-script.php user_to_look_for
The script will exit zero on success (the user exists) or exit 1 if not. It currently echoes OK or Failed also but I can easily turn that off.
So, my question is, how do I have pam_exec call my script to look for user accounts, before looking on the actual host system for user accounts?
I've got it working. The way to do this is to set the AuthorizedKeysCommand and AuthorisedKeyUser settings of openssh in sshd_config. There is a caveat, the reason that github and others provide ssh as a service through a single login user shared among customers is that the user being called must be resolvable by the system being logged into, so they muxt exist locally, or the user db must be connected to a remote source like LDAP, which would also then have to be integrated into the application.
The way to get around this though, is that the AuthorizedKeyCommand can take parameters, %u for username, and also in this case %k for key or %f for sha256 fingerprint of the key. Then, that script can ignore the generic username it was given, and then just check the database for a match for the key or fingerprint. If we find it, we have the user for that key and successful authentication. If not we dont.
I have gitolite installed. I'm able to administer it fine. I've added a few new repos, and a few pub keys. Installed as 'git#domain.com' and a repo added for a user as repo.git.
Does it have to be git#domain.com:repo.git to access, or is there a way to indicate the user in the url?
Possibly something like user#domain.com:repo.git or git.domain.com/user/repo.git for example?
No, it has to be git#domain.com because the user is always the same: the git account you are using to install and administer gitolite on your server.
The actual user is deduced from the public key you are using when making your ssh call.
If you registered that key with the user.pub file representing said public key named after the user's login, then gitolite will be able to identify you.
For more, see "how gitolite uses ssh".
If you look in the authorized_keys file, you'll see entries like this (I chopped off the ends of course; they're pretty long lines):
command="[path]/gitolite-shell sitaram",[more options] ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEA18S2t...
command="[path]/gitolite-shell usertwo",[more options] ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEArXtCT...
First, it finds out which of the public keys in this file match the incoming login.
Once the match has been found, it will run the command given on that line; e.g., if I logged in, it would run [path]/gitolite-shell sitaram.
So the first thing to note is that such users do not get "shell access", which is good!
When gitolite-shell gets control, it looks at the first argument ("sitaram", "usertwo", etc) to determine who you are. It then looks at the SSH_ORIGINAL_COMMAND variable to find out which repository you want to access, and whether you're reading or writing.
Now that it has a user, repository, and access requested (read/write), gitolite looks at its config file, and either allows or rejects the request.
Let's say I have a user "appuser" on a linux system with a number of public keys set up in their authorized_keys file where several different people can log in as "appuser".
When I log in using my private key that is linked to my public key, is what I do as the "appuser" traceable back to me? (I want it to be). If the activity is not traceable back to the identity of the user that logged in as app user, is there a way to make it traceable back to that identity?
The authorized_keys file allows for some options, including 'command' which will call a program or script you can write. I haven't tried this, but you might be able to perform whatever actions you need to in the script and then exec bash (or your shell of choice).
Another way you can match logins with keys is to turn LogLevel in sshd_config to VERBOSE and grep /var/log/secure (or whatever AUTHPRIV messages are going to) for 'Found matching .* key'. You can run the key found in the 'Found matching' line through 'ssh-keygen -l -f' which will dump the matching entry in authorized_keys.
I have a remote server to which I login using ssh. Is there a way to be notified through email (using a bash script) when someone changes the user password using passwd including the new password?
I am guessing it has to do with /etc/pam/passwd, but not entirely sure what the trigger and flags should be.
This would be useful if for example I give my access to a "friend" and they decide to lock me out of my account. Of course I could create a new account for them etc, but this is more of a "it should be possible" task rather than a practical one.
First, a Dope Slap
There's a rule that this question reminds me of... What is it? Oh yeah...
NEVER SHARE YOUR PASSWORDS WITH ANYONE!
Which also goes well with the rule.
NEVER SEND SOMETHING SECRET THROUGH EMAIL!
Sorry for the shouting. There's a rule in security that the likelihood a secret will get out is the square of the number of people who know it. My corollary is:
if ( people_who_know_secret > 1 ) {
It ain't a secret any more
}
In Unix, even the system administrator, the all powerful root, doesn't know your password.
Even worse, you want to email your password. Email is far from secure. It's normally just plain text sent over the Aether where anyone who's a wee bit curious can peek at it.
Method One: Allowing Users to use SSH without Knowing Your Password
Since you're using SSH, you should know that SSH has an alternate mechanism for verifying a user called Private/Public keys. It varies from system to system, but what you do is create a public/private key pair. You share your public key with the system you want to log into, but keep your private key private.
Once the remote machine has your public key, you can log into that system via ssh without knowing the password of that system.
The exact mechanism varies from machine to machine and it doesn't help that there are two different ssh protocols, so getting it to work will vary from system to system. On Linux and Macs, you generate your public/private key pair through the ssh-keygen command.
By default, ssh-keygen will produce a file called $HOME/.ssh/id_rsa.pub and $HOME/.ssh/id_rsa. The first one is your public key. You run ssh-keygen on both your machine and the machine you want to log into.
On the machine you're logging into, create a file called $HOME/.ssh/authorized_keys, and copy and paste your public key into this file. Have your friend also send you his public key, and paste that into the file too. Each public key will take up one line in the file.
If everything works, both you and your friend can use ssh to log into that remote machine without being asked for a password. This is very secure since your public key has to match your corresponding private key. If it doesn't you can't log in. That means even if other popel find your public key, they won't be able to log into that remote system.
Both you and your friend can log into that system without worrying about sharing a password.
Method Two: A Better Solution: Using SUDO
The other way to do this is to use sudo to allow your friend to act as you in certain respects. Sudo has a few advantages over actually sharing the account:
All use of SUDO is logged, so you have traceability. If something goes wrong, you know who to blame.
You can limit what people can do as SUDO. For example, your friend has to run a particular command as you, and nothing else. In this case, you can specify in the /etc/sudoers file that your friend can only run that one particular command. You can even specify if your friend can simply run the command, or require your friend to enter their password in order to run that command.
On Ubuntu Linux and on Macintoshes, the root password is locked, so you cannot log in as root. If you need to do something as root, you set yourself up as an administrator (I believe by putting yourself in the wheel group) and then using sudo to run required administrator functions.
The big disadvantage of Sudo is that it's more complex to setup and requires administrator access on the machine.
Try setting up public/private keys using SSH. It might take some tweaking to get it to work, but once it works, it's beautiful. Even better, you can run remote commands and use sep to copy files from one machine to the other -- all without the password prompt. This means that you can write shell scripts to do your work for you.
By the way, a sneaky trick is to set your remote shell to /bin/false. That way, you can't log into that system -- even using ssh, but you can run remote commands using ssh and use sep to copy files back and forth between systems.
Personal passwords are only supposed to be known by the user themselves. Not even the root user is supposed to know them, which is why they are stored encrypted. Of course, the root user has sufficient access to decrypt them, but the principle is the same.
If you are giving your "friend" access, them assign them proper privileges! Do not make them a root user, and you shouldn't be a root user either. Then you're "friend" won't have access to change your password, let along muck about in areas they aren't supposed to be in.
If you absolutely must monitor the passwd and shadow files, install iwatch. Then set it to watch the /etc/passwd and /etc/shadow files. If they change, it runs a script that decrypts the file and emails someone. If you keep a copy to diff against, you'll even know who changed. You should probably also gpg the email, so that it does not go over the internet in plain text, since it has everyone's password in it. Please note that any other users on the system will be upset by the dystopian world they find themselves in.
Just because root is the law of the land does not mean we want to be living in 1984.
Try some kind of:
alias passwd='passwd && echo 'Alert! Alert! Alert!' | mail -s 'pass change' alert#example.com'
Should be enough for you:)
Another possible solutions for those, who think, that alias is too mainstream)) :
1) You could make a cron job, that will be checking your /etc/shadow file every, for example, minute, and when the file changes, it will send you an alert-email. The easiest way here, I think, will be making md5 checksum
2) You can move /usr/bin/passwd to /usr/bin/passwd.sys and make a script with /usr/bin/passwd.sys && echo 'Alert! Alert! Alert!' | mail -s 'pass change' on it's place. And yes, this way is also could be discovered be the user and scrubed round:)
I'm new to shellscripting (and not well traveled in the world of Linux) and are trying to get a shellscript to automaticly log into an sftp server with my given. Now this is how far I've gotten
#!/bin/bash
HOST='somehost.com'
USER='someusername'
PASSWD='somepass'
sftp $USER#$HOST
Now this is where I run into trouble. At this point I will be prompted for a password. So how do I get the script to automaticly reply with the password when prompted for it? I also tried finding a way to pass along the password with the sftp command, but with no luck. Can anyone help me figure this out?
Use this code:
#!/bin/bash
HOST='somehost.com'
USER='someusername'
PASSWD='somepass'
echo $PASSWD | sftp $USER#$HOST
It's not a good idea to include the password in a command line or such a script. Anyone who has access to the list of running processes could see your password, it could end up in your shell history and log files. So this would create a security hole.
There is more info in this thread where key based authentication is recommended over your proposed method.
Do not store passwords in script files, unless you are compulsive obsessive about keeping your permissions absolutely tight.
For all things ssh/sftp/scp, use public key authentication. Learn about the settings you can set on both the client and the server ends to make it more secure (ip restrictions, user restrictions, cipher restrictions, number of retries, number of simultaneous logins, etc) That alone should eliminate a lot of insecurity due to scripting issues.
If you absolutely must store a password in a variable, do not export it, and unset it the moment you get done using it.
on local host (where the script will be executed) generate ssh key pair:
scriptuser#scripthost:/~$ ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/michal/.ssh/id_rsa): {press ENTER!}
(...)
copy generated public key from scripthost to the somehost.com and append it to the list of authenticated hosts:
scriptuser#scripthost:/~$ cat ~/.ssh/id_rsa.pub | ssh someuser#somehost.com 'cat >> .ssh/authorized_keys'
now you should be able to use scp or sftp without password:
scriptuser#scripthost:/~$ scp /any/local/file someuser#somehost.com:/remote/location/
use sshpass command.
you can give password along with command