Authentication to ROOT servers (TServerSocket)
==============================================

Servers based on TServerSocket accept 5 methods of authentication, listed
in Table 1, together with their internal codes and short names.
Method 5 (uidgid) is provided for fast access when security is not an issue.
Method 0 is 'secured' by using a session public key, automatically
generated, which allows to avoid direct exchange of passwords.

   Table 1: authentication methods available
 +---------------------------------------------------------------------+
 | Method              | code | short name | in .rootrc | Secure | Sfx |
 |---------------------------------------------------------------------|
 | (user,password)     |  0   | usrpwd     | UsrPwd     |  Yes   | up  |
 | SRP                 |  1   | srp        | SRP        |  Yes   | s   |
 | Kerberos V          |  2   | krb5       | Krb5       |  Yes   | k   |
 | Globus GSI          |  3   | globus     | Globus     |  Yes   | g   |
 | (uid,gid)           |  5   | uidgid     | UidGid     |  No    | ug  |
 +---------------------------------------------------------------------+

By default method 0 (UsrPwd) is used; host equivalence via /etc/hosts.deny
and/or $HOME/.rhosts is tested (by default; it can be disabled).

A specific method can be given priority by adding the suffix shown in the
table (column Sfx) to the specified protocol: for example

  TFile *f = TFile::Open("roots://host.doma.in/~fserv/TheFile.root","read")

requires the use of the SRP method.

Defaults can be changed on {host, user} base via the file $HOME/.rootauthrc;
the header of the file $ROOTSYS/etc/system.rootauthrc, automatically generated
upon configuration with system defaults based on the compilation options,
contains the explanation of the syntax for the available directives and
examples of use.
Defaults specified by directives in the .rootrc family files (in order of
priority: $HOME/.rootrc, /etc/root/system.rootrc and $ROOTSYS/etc/system.rootrc)
are still considered for backward compatibility but with the lowest priority.
It is also possible to specify authentication directives interactively
as explained below.

A test macro TestAuth.C is provided under the tutorials directory. Its use
is explained at the end of this file.

Controlling access
==================

Directives defining the authentication protocols accepted from a given host
are defined in the active <rootdaemonrc> file; this file is by default
$ROOTSYS/etc/system.rootdaemonrc; if existing, $HOME/.rootdaemonrc has
priority; it is also possible to use a generic filename and location.
The two last solutions have the advantage that the file do not get
reset if the ROOT distribution needs to be re-configured.

By default the ROOT daemons accept authentications only via the methods
defined by the directive more closely matching the requesting hosts.
The file $ROOTSYS/etc/system.rootdaemonrc is automatically generated
upon configuration with the list of available secure methods enabled
by default from all the hosts.
The administrator of the daemons has the responsibility to add the relevant
entries to fit the site access policy.


Negotiation
===========

Simple negotiation is supported as follows. The client sends the preferred
method (the first one in the list, see below) to the server; if this is among
the methods accepted by the server (not necessarily the one preferred by the
server) authentication is attempted. In the case the attempt is unsuccessful,
the server sends back the list of the remaining methods accepted (if any); the
client compares the server list with its own list of remaining methods and
makes a new attempt if the overlap of the two lists is not empty; and so on.

Entries in .rootrc
==================

The authentication related entries in the .rootrc family of files define
directives applying to all remote host and all remote accounts. The available
directives are the following:

* The <method>.Login directives specify the default login for the method:

  UsrPwd.Login, SRP.Login, UidGid.Login:   <username>   (e.g.: qwerty)
  Krb5.Login:    <principal>                       (e.g.: qwerty@THIS.DOM.AIN)
  Globus.Login:   cd:<dir_with_my_certs> cf:<my_cert_file> \
                  kf:<my_key_file> ad:<dir_with_CA_certs>

* The <method>.LoginPrompt directives specify whether root should prompt you
  for the login (with default the login specified via <method>.Login; possible
  values are 0 or no for no prompt, 1 or yes to have the prompt; valid
  examples:

  UsrPwd.LoginPrompt:   0
  Krb5.LoginPrompt:     1
  Globus.LoginPrompt:   no

  Default is no prompt.

  For anonymous 'usrpwd' login, 'UsrPwd.LoginPrompt 0' implies automatic
  generation of the password in the form <user>@<local_host_fqdn>, where <user>
  is obtained from the variable USER or from ' getpwuid(getuid())->pw_name '.

* The <method>.ReUse directives specify whether root reuse valid authentication
  once established; possible values are '0' or 'no' for OFF, '1' or 'yes' for ON.
  When this option is active, the client generates a session RSA key pair and
  transmits the public key to the server; the server generates a session 'token'
  which can be used by the client for later access to the server.
  This facility is implemented for all methods except UidGid (for which there would
  be no advantage); it is switched ON by default for UsrPwd, SRP and Globus,
  since it allows to speed up repeated access to the same server.
  For Krb5 it is implemented but switched OFF by default, since it does not improve
  on authentication time.

  UsrPwd.ReUse   yes
  SRP.ReUse      1
  Krb5.ReUse     0
  Globus.ReUse   yes

  NB: unless 'UsrPwd.Crypt 0' (see below), for UsrPwd the password is always sent
      encrypted with the session RSA key, even if UsrPwd.ReUse is OFF.

* The <method>.Valid directives specify the duration validity of the security
  context for methods UsrPwd and SRP; values are passed in the form
  <hours>:<min>, the default being 24:00 .

  UsrPwd.Valid  16:45
  SRP.Valid     13:00

* Other directives

  * UsrPwd

    * To secure password exchange set (this is the default)

      UsrPwd.Crypt   1

      A session key pair is generated and used to encrypt the password hash to
      be communicated to the server.

  * globus

    * to change the duration in hours of globus credentials (default is 12) use
      Globus.ProxyDuration:     <hours>

    * to change the number of bits in the key (default 1024)
      Globus.ProxyKeyBits:      <bits>
      where <bits> is 512 or 1024 or 2048 or 4096

.rootauthrc
===========

The .rootauthrc file allow to specify host and user specific instructions; all
the possibilities are explained in etc/system.rootauthrc. The information read
is used to instantiate THostAuth objects; these can be modified during the root
session as explained in the next session.


Modifying/Adding authentication info during the session
=======================================================

Remote authentication in root is controlled by the TAuthenticate class;
TNetFile and TSlave create a TAuthenticate object before proceeding to
authentication.

Authentication is (host,user) specific. The dedicated class THostAuth contains
the information for a specific (host,user):

       + remote host FQDN
       + user name
       + number of available methods (n)
       + method internal codes (dimension n)
       + login info for each method (dimension n)
       + list of established authentication

The available methods are listed in order of preference: the first one is the
one preferred, the others are tried in turn upon failure of the previous one,
and if accepted by the remote daemon (see Negotiation below).

THostAuth objects are instantiated by TAuthenticate at first call using
the information found in $HOME/.rootauthrc or $ROOTSYS/etc/system.rootauthrc.
The list of THostAuth is refreshed if any of the relevant file has changed
since last TAuthenticate call, so the best way to change authentication
directives during an interactive session is to edit the $HOME/.rootauthrc.
Nonetheless, a set of methods are available in the TAuthenticate and THostAuth
classes to display/modify/create THostAuth interactively.

 * void TAuthenticate::Show(<opt>)

   Prints information about authentication environment:

      <opt> = "s" list of active security context (default)
              "h" the content of the instantiated THostAuth objects in
                  standard list

   Example:

root [6] TAuthenticate::Show()
Info in <TSecContext::Print>: +------------------------------------------------------+
Info in <TSecContext::Print>: + Host:pceple19.cern.ch Method:0 (UsrPwd) User:'ganis'
Info in <TSecContext::Print>: +         OffSet:0 Details: 'pt:0 ru:1 cp:1 us:ganis'
Info in <TSecContext::Print>: +         Expiration time: Sat Jan 10 13:18:41 2004
Info in <TSecContext::Print>: +------------------------------------------------------+


root [7] TAuthenticate::Show("h")
Info in <::Print>:  +--------------------------- BEGIN --------------------------------+
Info in <::Print>:  +                                                                  +
Info in <::Print>:  + List fgAuthInfo has    5 members                                 +
Info in <::Print>:  +                                                                  +
Info in <::Print>:  +------------------------------------------------------------------+
Info in <THostAuth::Print>:  +------------------------------------------------------------------+
Info in <THostAuth::Print>:  + Host:default - User:* - # of available methods:6
Info in <THostAuth::Print>:  + Method: 0 (UsrPwd) Ok:0 Ko:0 Dets:pt:no ru:yes cp:yes us:
Info in <THostAuth::Print>:  + Method: 1 (SRP) Ok:0 Ko:0 Dets:pt:no ru:no us:
Info in <THostAuth::Print>:  + Method: 2 (Krb5) Ok:0 Ko:0 Dets:pt:no ru:no us:
Info in <THostAuth::Print>:  + Method: 3 (Globus) Ok:0 Ko:0 Dets:pt:no ru:yes
Info in <THostAuth::Print>:  + Method: 5 (UidGid) Ok:0 Ko:0 Dets:pt:no us:
Info in <THostAuth::Print>:  +------------------------------------------------------------------+
Info in <THostAuth::PrintEstablished>: +------------------------------------------------------------------------------+
Info in <THostAuth::PrintEstablished>: + Host:default - Number of active sec contexts: 0
Info in <THostAuth::PrintEstablished>: +------------------------------------------------------------------------------+
Info in <THostAuth::Print>:  +------------------------------------------------------------------+
Info in <THostAuth::Print>:  + Host:pcep*.cern.ch - User:* - # of available methods:2
Info in <THostAuth::Print>:  + Method: 0 (UsrPwd) Ok:1 Ko:0 Dets:pt:no ru:1 us:ganis
Info in <THostAuth::Print>:  + Method: 1 (SRP) Ok:1 Ko:0 Dets:pt:yes ru:no us:ganis
Info in <THostAuth::Print>:  +------------------------------------------------------------------+
Info in <THostAuth::PrintEstablished>: +------------------------------------------------------------------------------+
Info in <THostAuth::PrintEstablished>: + Host:pcep*.cern.ch - Number of active sec contexts: 1
Info in <TSecContext::PrintEstblshed>: + 1) h:pceple19.cern.ch met:0 (UsrPwd) us:'ganis'
Info in <TSecContext::PrintEstblshed>: +    offset:0 det: 'pt:0 ru:1 cp:1 us:ganis'
Info in <TSecContext::PrintEstblshed>: +    expiring: Sat Jan 10 13:18:41 2004
Info in <THostAuth::PrintEstablished>: +------------------------------------------------------------------------------+
Info in <THostAuth::Print>:  +------------------------------------------------------------------+
Info in <THostAuth::Print>:  + Host:lxplus*.cern.ch - User:* - # of available methods:2
Info in <THostAuth::Print>:  + Method: 1 (SRP) Ok:0 Ko:0 Dets:pt:no ru:1 us:ganis
Info in <THostAuth::Print>:  +------------------------------------------------------------------+
Info in <THostAuth::PrintEstablished>: +------------------------------------------------------------------------------+
Info in <THostAuth::PrintEstablished>: + Host:lxplus*.cern.ch - Number of active sec contexts: 0
Info in <THostAuth::PrintEstablished>: +------------------------------------------------------------------------------+
Info in <::Print>:  +---------------------------- END ---------------------------------+

   The method THostAuth::PrintEstablished is also called, displaying the
   relevant info about the established security context(s) saved in TSecContext.

root [8] TAuthenticate::Show("p")
Info in <::Print>:  +--------------------------- BEGIN --------------------------------+
Info in <::Print>:  +                                                                  +
Info in <::Print>:  + List fgProofAuthInfo has    1 members                            +
Info in <::Print>:  +                                                                  +
Info in <::Print>:  +------------------------------------------------------------------+
Info in <THostAuth::Print>:  +------------------------------------------------------------------+
Info in <THostAuth::Print>:  + Host:lxplus*.cern.ch - User:ganis - # of available methods:2
Info in <THostAuth::Print>:  + Method: 1 (SRP) Ok:0 Ko:0 Dets:pt:no ru:1 us:ganis
Info in <THostAuth::Print>:  +------------------------------------------------------------------+
Info in <::Print>:  +---------------------------- END ---------------------------------+

  This is the list build following the directives in .rootauthrc

 * THostAuth *TAuthenticate::GetHostAuth(<host_fqdn>,<user>,<opt>,<kExact>);

   Returns a pointer to the THostAuth object pertaining to (host,user) if it
   exist, 0 otherwise. If <opt>="R" (default) the search is performed in the
   standard list. The last argument <kExact>
   is a pointer to an integer: if defined (.ne. 0) the pointed location is
   filled with 1 if the match is exact, with 0 if an matching entry with wild
   cards was found.

   Example:

   root [2] THostAuth *ha = TAuthenticate::GetHostAuth("pcepsft43.cern.ch","ganis")
   root [3] printf("ha: 0x%x\n",(int)ha);
   ha: 0x88df970
   root [4] THostAuth *ha = TAuthenticate::GetHostAuth("der.mit.ow","scruno")
   root [5] printf("ha: 0x%x\n",(int)ha);
   ha: 0x0
   root [6]

 * void TAuthenticate::RemoveHostAuth(THostAuth *ha)

   Removes and destroys the THostAuth object pointed by ha from the static list
   in TAuthenticate

 * void THostAuth::Print()

   Prints the information contained in this THostAuth object

   Example:

root [10] ha->Print()
Info in <THostAuth::Print>:  +------------------------------------------------------------------+
Info in <THostAuth::Print>:  + Host:pcep*.cern.ch - User:* - # of available methods:2
Info in <THostAuth::Print>:  + Method: 0 (UsrPwd) Ok:1 Ko:0 Dets:pt:no ru:1 us:ganis
Info in <THostAuth::Print>:  + Method: 1 (SRP) Ok:1 Ko:0 Dets:pt:yes ru:no us:ganis
Info in <THostAuth::Print>:  +------------------------------------------------------------------+

   The statistics for successful or unsuccessful use of the indicated methods
   are shown after "Ok:" and "Ko:", respectively.


 * void THostAuth::AddMethod(<code>,<login_inf>)

   Add a new method (internal code <code>, login information <login_info>) at
   the end of the list of available methods

   Example (with respect to above):

   root [9] ha->AddMethod(0,"no us:ganis")
   root [10] ha->Print()
   Info in <THostAuth::Print>: +------------------------------------------------------------------+
   Info in <THostAuth::Print>: + Host:pcepsft43.cern.ch - User:ganis - # of available methods:4
   Info in <THostAuth::Print>: + Method: 3   Details:pt:no cd:~/.globus cf:usercert.pem kf:userkey.pem ad:certificates
   Info in <THostAuth::Print>: + Method: 4   Details:pt:no ru:1 us:ganis
   Info in <THostAuth::Print>: + Method: 1   Details:pt:no ru:1 us:ganis
   Info in <THostAuth::Print>: + Method: 5   Details:pt:yes us:ganis
   Info in <THostAuth::Print>: + Method: 0   Details:pt:no us:ganis
   Info in <THostAuth::Print>: +------------------------------------------------------------------+
   root [11]

 * void THostAuth::RemoveMethod(<code>)

   Removes method with internal code <code> from the list of available methods

   Example (with respect to above):

   root [9] ha->RemoveMethod(5)
   root [10] ha->Print()
   Info in <THostAuth::Print>: +------------------------------------------------------------------+
   Info in <THostAuth::Print>: + Host:pcepsft43.cern.ch - User:ganis - # of available methods:4
   Info in <THostAuth::Print>: + Method: 3   Details:pt:no cd:~/.globus cf:usercert.pem kf:userkey.pem ad:certificates
   Info in <THostAuth::Print>: + Method: 4   Details:pt:no ru:1 us:ganis
   Info in <THostAuth::Print>: + Method: 1   Details:pt:no ru:1 us:ganis
   Info in <THostAuth::Print>: + Method: 0   Details:pt:no us:ganis
   Info in <THostAuth::Print>: +------------------------------------------------------------------+
   root [11]

 * void THostAuth::SetDetails(<code>,<login_inf>)

   Changes login info for method with internal code <code> to <login_info>; if
   it does not exist, add a this as new method.

   Example (with respect to above):

   root [11] ha->SetDetails(4,"pt:no ru:1 us:gganis")
   root [12] ha->Print()
   Info in <THostAuth::Print>: +------------------------------------------------------------------+
   Info in <THostAuth::Print>: + Host:pcepsft43.cern.ch - User:ganis - # of available methods:4
   Info in <THostAuth::Print>: + Method: 3   Details:pt:no cd:~/.globus cf:usercert.pem kf:userkey.pem ad:certificates
   Info in <THostAuth::Print>: + Method: 4   Details:pt:no ru:1 us:gganis
   Info in <THostAuth::Print>: + Method: 1   Details:pt:no ru:1 us:ganis
   Info in <THostAuth::Print>: + Method: 0   Details:pt:no us:ganis
   Info in <THostAuth::Print>: +------------------------------------------------------------------+
   root [13]

 * void THostAuth::SetFirst(<code>)

   Set method with internal code <code> as the preferred one, if it exists.

   Example (with respect to above):

   root [13] ha->SetFirst(1)
   root [14] ha->Print()
   Info in <THostAuth::Print>: +------------------------------------------------------------------+
   Info in <THostAuth::Print>: + Host:pcepsft43.cern.ch - User:ganis - # of available methods:4
   Info in <THostAuth::Print>: + Method: 1   Details:pt:no ru:1 us:ganis
   Info in <THostAuth::Print>: + Method: 3   Details:pt:no cd:~/.globus cf:usercert.pem kf:userkey.pem ad:certificates
   Info in <THostAuth::Print>: + Method: 4   Details:pt:no ru:1 us:gganis
   Info in <THostAuth::Print>: + Method: 0   Details:pt:no us:ganis
   Info in <THostAuth::Print>: +------------------------------------------------------------------+
   root [15]

 * void THostAuth::AddFirst(<code>,<login_inf>)

   Set method with internal code <code> as the preferred one, and changes the
   login information to <login_inf>. If it does not exist, add a new method in
   first position.

 * void THostAuth::ReOrder(nmet,meths)

   Reorder the list of the available methods in such a way that the first nmet
   methods are the ones listed in meths[nmet].

 * Bool_t  THostAuth::IsActive() const { return fActive; }

   Indicates if this THostAuth instantiation is active

 * void    THostAuth::DeActivate() { fActive = kFALSE; }

   Sets this THostAuth instantiation inactive

 * void    THostAuth::Activate() { fActive = kTRUE; }

   Sets this THostAuth instantiation active

 * void    THostAuth::Reset();

   Resets content of this THostAuth instantiation

TSecContext
============

The class TSecContext contains the relevant details about an established security
context, typically needed for re-usage of the context.

authserv.C, authclient.C
========================

These macros must be run together to test authentication between two remote
ROOT sessions.
Run first the authserv.C within a ROOT session on the server
machine, eg. "srv.machi.ne":

          root[] .x authserv.C(3000)

authserv accepts as argument the port where it starts listening
(default 3000).
You can then run authclient.c in a ROOT session on the client machine:

          root[] .x authclient.C("srv.machi.ne:3000")

and you should get prompted for the credentials, if the case.
To start a parallel socket of size, for example, 5, enter the
size as second argument, ie

          root[] .x authclient.C("srv.machi.ne:3000",5)


--------------------------------------------------------------------------------------
Last update: November 19, 2018
