Abstract:
An apparatus for importing and exporting computer based configuration data to and from text based files in which part of the data is encrypted for confidentiality. The apparatus allows the resulting text file to be selectively edited prior to an import, providing for flexibility on behalf of system administrators without compromising the security of encrypted data.

Description:
REFERENCES 
     [1] Stevens, W. Richard,  Unix Network Programming  (Prentice-Hall, 1990), pages 24-25. 
     [2]  ExtendNet VPN Reference Guide  (Extended Systems Inc., June, 1997) 
     [3] Schneier, Bruce,  Applied Cryptography, Second Edition  (Wiley, 1996), pages 30-31, 265-269, 435-436 
     [4] Wright, Gary R.,  TCP/IP Illustrated, Volume  2 (Addison-Wesley, 1995), pages 64-65. 
     FIELD OF THE INVENTION 
     This invention relates to an apparatus to import and export computer configuration data, part of which is confidential, to and from plain-text computer files. 
     BACKGROUND 
     Modern computing environments consist of computer networks with multiple servers for performing many varied functions. Often access to a server or other network resource is limited to users(clients) who can present proper credentials to the server. The process of identifying one&#39;s self to a computer system is generally known as authentication, and often consists of the client logging on to a system by entering a user name followed by a password. If the password entered in by the client matches that maintained in a list by the server, the user is considered authenticated, and is logged into the server. Authenticated clients are then allowed access to the resources and services provided by the particular server according to the privilege level associated with the user name. 
     Modern computer networks typically have multiple servers. On a computer network with multiple servers, it is often desirable to have multiple user name/password lists, and each server is generally associated with a single user name/password list. The user name/password lists are typically grouped with other server specific data. The collection as a whole represents the configuration data for a particular server. 
     For example, a remote access server is a device that allows remote users to access network computing resources from a remote site such as home or a customer site. The network itself generally has its own configuration data, including its own user name and password lists to authenticate users to the network at large. Thus in the general case, a remote user must authenticate to the remote access server, and then, having done that, gain access to the network itself. 
     Administering user name/password configuration files in a multi-server environment is difficult. It is desirable to be able to make backup copies of configuration data from each server that can be stored in a secure place on the network. The stored configuration file can be used to restore the configuration of a server that becomes corrupted. It sometimes is useful to replicate user/names and passwords across multiple servers when, for example, simultaneous user capacity is being increased by adding additional servers. The user/name password lists tend to be large and contain confidential passwords, making it impractical and undesirable to enter the data by hand, so the ability to transfer memory based server configuration data to a file is important. Such a file, however, poses security challenges, because certain configuration data, such as passwords, is confidential and should not be disclosed. One common solution for protecting passwords when written to a text file is to hash them with a one-way hash. Unix, for example, does not store the plain-text versions of passwords. Instead, Unix stores a one way hash of the password. The hashing algorithm is a well-known algorithm. When a password is presented by a user, it too is hashed with the same algorithm, and the hashes are compared to determine if the original passwords match. One limitation of one way hash schemes is that the original clear-text password is not preserved on the server which is undesirable if the plain-text password is needed for another server purpose, such as an encryption key for data files. 
     Another prior art solution to protect confidential passwords is to encrypt the entire configuration file; this solution suffers from the fact that the entire configuration file, including public data, is encrypted and thus unreadable and difficult to modify. 
     What is needed is a system for saving and restoring configuration data to and from a text file that permits editing of public configuration data, preserves the secrecy of private configuration data, and ensures that improperly modified text files by unauthorized persons are blocked from restoration on a server. 
     BRIEF SUMMARY AND OBJECTS OF THE INVENTION 
     It is an object of the present invention to provide an apparatus that allows system administrators to be able to save, restore, and replicate server configuration data such as user names and passwords into a text file without compromising the secrecy of the passwords and other secure data, and further, to allow the resulting text files to optionally be edited in part, and to be restored to the same or different virtual private network server in a secure way. 
     The present invention achieves this objective by introducing a novel system that allows user configuration data, including names and passwords, to be saved in a textual data file by an authorized, authenticated system administrator, who provides an additional encryption password for the data when the configuration file is created. Selected portions of the data, such as passwords and other confidential data, are encrypted prior to being written to the file. The remaining information is written in an unencrypted form. The public portion of the configuration file can be restored on any server by an administrator authenticated to that server, including an administrator who cannot provide the decryption password associated with the configuration file. The entire configuration file, including the private, encrypted data, can be restore on any server, providing that the administrator authenticated to that server also can provide the decryption password associated with the configuration file. 
     The present invention is particularly novel in the way it performs a restore when the data authentication fails because the system administrator cannot present the proper decryption password. The present invention discloses a system having a data decryption password associated with the configuration file, the decryption password is distinct from the authentication password needed to authenticate to a target server. Rather than simply deny a restoration if the data authentication fails, the present invention allows a system administrator authenticated to the server, but not to the data, to restore the public parts of a configuration file, thus allowing public configuration data to be replicated freely. 
     The present invention also allows configuration data to be selectively excluded from a restore. 
    
    
     BRIEF DESCRIPTIONS OF THE DRAWINGS 
     FIG. 1 shows a simplified example of a configuration variable table as it applies to the present invention. 
     FIG. 2 shows a simplified example of the text of a persistent configuration text file as it applies to the present invention. 
     FIG. 3 is a block diagram of the present invention in a client-server context. 
     FIG.  4 . is a block diagram of the present invention in a single device context. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 show a simplified representation of a memory-base configuration variable table. Each row represents a memory configuration variable, each column represent an attribute of the variable thus identified. The memory identifier column  350  contains a value for identifying the configuration variable to the server. The memory value column  355  contains the current value of the identified variable. The private or public flag column  360  distinguishes private data from public data. In FIG. 1., the data enclosed in brackets in memory column  355  denotes a binary representation of sample data, the data enclosed in quotation marks denotes the clear text representation of the binary data. The private or public column  360  is used primarily to distinguish private data that is to be encrypted before being written to a configuration file from public data, written in clear-text form. The preferred embodiment uses Simple Network Management Protocol(SNMP) [4] object identifiers for the memory identifiers  350 . In the preferred embodiment, user passwords, the SNMP get community name, and the SNMP set community name are private data. The remaining configuration data is public. In the preferred embodiment the configuration variable table  345  illustrated in FIG. 1 is implemented logically as described, although some of the columns are implicit. In particular, the private or public column  360  is implicitly by code logic rather than an explicit table entry. 
     The textual identifier column  370  denotes the textual name of the variable used to identify the variable in a configuration text file. The textual value  375  denotes the textual value of the variable as it would appear in a textual configuration file. Note that for the three public variables in FIG. 1, the textual value  375  corresponds to the clear-text value of the memory variable  355 . The only private variable  360  in FIG. 1 is password, its textual value  375  is an encrypted form of the clear text value  355 . 
     FIG. 3 is a block diagram that generally shows the preferred embodiment. The perferred embodiment is generally implemented as the ExtendNet VPN 1000 [2], a commercial product. The ExtendNet VPN includes both a discrete Virtual Private Network (VPN) server and a server management utility commercially known as InterprEYES. In the preferred embodiment, the server  600  is a VPN server. 
     The configuration variable table  345  of the preferred embodiment contains numerous variables including general configuration variables such as the system name, the system contact, the system level, a trace level for debug purposes, the admin console IP address, the admin console IPX network, and the admin console IPX node. The configuration variable table  345  in the preferred embodiment also contains a network configuration section, including a user authentication code, and a packet compression bitmask. The configuration variable table  345  in the preferred embodiment also contains a variable for each user having permission to use the VPN. Each user configuration variable includes a user name, user password, a web access flag, and an account disabled flag. The configuration variable table  345  in the preferred embodiment also contains a server TCP/IP configuration section, including an IP address, a subnet mask, a default gateway, a connection timeout checking flag, a firmware update TFTP port, and a boot protocols section variable. The configuration variable table  345  in the preferred embodiment also contains a client TCP/IP configuration section including a client TCP/IP enable flag, a cleint-to-client communication flag, and address source variable to indicate whether client ip address come from an internal table or form a DHCP server, the primary DNS server IP address, the secondary DNS server IP address, the primary NetBios name server IP address, the and secondary NetBios name server IP address. The configuration variable table  345  in the preferred embodiment also contains a IPX configuration section including an IPX enable flag, an IPX frame format variable, a SAP interval variable, a client enable flag, a client network number variable, and a client-to-client communication flag. The configuration variable table  345  in the preferred embodiment also contains SNMP configuration section including the trap community name, the get community name, and the set community name. The configuration variable table  345  in the preferred embodiment also contains a trap configuration section including an urgent traps bitmask, a warning traps lists, an information traps list, and a debug traps list. 
     In the preferred embodiment, the encryption/decryption apparatus  610  is a software routine deploying well known encryption algorithm Data Encryption Standard DES [4], and the encryption key is the data password  550 . The server configuration import/export apparatus  620  is a software routine that resides within the server  600 . The server configuration import/export apparatus  620  is an SNMP [4] handler, which responds to read/write requests for individual SNMP variables, each SNMP variable is defined by an object identifier descripter (OID). During an export, upon a proper request via the SNMP interface, the server configuration import/export apparatus  620  receives an SNMP request containing an OID corresponding to a memory identifier  350  of the configuration variable table  345 . The corresponding memory identifier  350  and the corresponding textual value  375  are wrapped in an SNMP packet and transmitted via SNMP to the client import/export apparatus  525 . The public variables are transmitted in clear text; the private variables are encrypted by the encryption/decryption apparatus  610 , which is a software implementation of the well known 56 bit DES encryption algorithm. As a security measure, private data is return via SNMP only if the server  600  is put into a private data manipulation mode via a special SNMP call. Thus, if a general SNMP client will not be able to retrieve any private data, (even though the data would be encrypted), private data transmission is intended to be limited to the server management program  520 . 
     The server management program  520  is a Window  95 /Windows NT application program. The save/restore configuration control apparatus  530  of the preferred embodiment is a Windows menu selection, well known in the art. Specifically the menu selection “File—Export Configuration” for configuration export and “File—Import Configuration” for configuration import. 
     In the preferred embodiment, the server password  540  is a SNMP get/set community name pair and the data password  550  is arbitrarily chosen by an authenticated system administrator  500  at the time of an export. 
     The client configuration import/export apparatus  525  also can optionally contain a mechanism to selectively prohibit the restoration of certain variables. This mechanism is useful in situations where a full restore would change system variables such as server passwords and addresses that are preferably left unchanged in some restorations. The mechanism typically consists of an internal table and a menu means for the system administrator  500  to identify the variables to be excluded from a restore. The table is then applied against each variable prior to it being sent to the server  600 , those variables within the table are not transmitted. 
     OPERATION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 3, to save a persistent configuration text file  510 , a system administrator  500  executes the server management program  520 . The system administrator  500  must present the server password  540  to authenticate to the server  600 , which in the preferred embodiment is a VPN server. Once authenticated, the system administrator  500  then invokes the save/restore configuration control apparatus  530  of the server management program  520 . The system administrator  500  provides a data password  550  and a file name for the persistent configuration text file  510 . In the preferred embodiment, the data password  550  serves both as an encryption/decryption key. The save request is transmitted to the configuration import/export apparatus  620  of the VPN server  600  via the SNMP protocol. The server configuration import/export apparatus  610  then initiates an export. The textual value  375  for each private variable is computed by encrypting the plain-text value  355  within the server  600  into an encrypted textual value  375  using the encryption/decryption apparatus  610  using an encryption key derived from the data password  550 . In the preferred embodiment, the encryption/decryption apparatus  610  is a software routine deploying well known encryption algorithm DES, and the encryption key is the data password  550   
     In the preferred embodiment, the client configuration import/export apparatus  525  performs the following steps when export is selected. First, the system administrator  500  is prompted via a dialog box to enter the data password  500 , then prompted to re-enter the passwords for verification. Next, the system administrator  500  is prompted to enter the configuration file  510  name. The export file is opened for output. An MD 4  hash digest signature of the data password  550  is written to the configuration file  510  in a textual form. The client/configuration import/export apparatus  525  contains a number of internal tables, each internal table corresponding to each section within the persistent text file  510 . Each table entry consists of an SNMP object identifier descriptor (OID), a data type, and a list of enumeration constants. 
     As a security measure, the SNMP interface, by default, will allow private data to be read or written (even though private data, when returned, is encrypted). The client configuration import/export apparatus sends a special SNMP call to turn on private data manipulation. After the export is complete an analogous SNMP call turns off private data manipulation. 
     Private data manipulation is turned on. Code for each table is invoked. For each section, section headers are written. For each variable in each table, an SNMP request call containing the oid of the variable is issued. When the data is returned, the data type and the enumeration constants are used to format the response into a suitable format. After formatting, each variable is written to the configuration file  510  . Each variable to is written the configuration file  510  using the textual identifier  370 , followed by an equal sign, followed by the textual value  375 , in a file format similar to Windows INI files. After the final section is written, the configuration file  510  is closed, and private data retrieval is turned off. 
     A configuration variable table  345  is restored analogously to the way it is saved. To restore a file on the same or different server  600 , the system administrator  500  must first authenticate to the target server  600  by providing the server password  540  to the server  600  using the server management program  520 . A restore command is issued through the server management program  520  via a menu command. The administrator  500  must then present the file name of the persistent configuration text file  510  and the data password  550 , which in the preferred embodiment also serves as the decryption key. In the preferred embodiment the encryption key, decryption key, and the data password  550  are identical but in general for some encryption/decryption methods they need not be, as long as the encryption key and the decryption key can be derived from the data password  550 . The save/restore configuration control apparatus hashes the data password  550  provided by the system administrator  500  into a digest form (using MD 4  in the preferred embodiment) and compares this new digest against the digest in the configuration file  510 . If the digests match, the system administrator  500  has entered the proper data password  550  and is authenticated and thus can import all the configuration data, including the private data. If the digests do not match, the administrator  500  is not authenticated to the data in the persistent configuration text file  510 , and thus can only import memory values in sets that have no private variables. In the preferred embodiment, the non-data authenticated system administrator can import neither user names nor passwords. If the system administrator  500  is authenticated to the data, the data password  550  is transmitted to the encryption/decryption apparatus  610  of the server configuration import/export apparatus  620  by a special SNMP call. 
     In the preferred embodiment, a section of the persistent configuration text file  510  is processed at a time. The section header is used to locate the corresponding internal section table. Variable data for that section is read from the persistent configuration text file  510 . The save/restore configuration control apparatus  530  validates that the particular variable belongs to the section. The save/restore configuration control apparatus  530  formats the value received from the persistent configuration text file  510  using the data type and enumeration constants from its internal tables into a format suitable for SNMP transmission and transmits the OID and the formatted value to the server configuration import/export apparatus  620 . The encryption/decryption apparatus  610  of the server  600  decrypts the private data, and the server configuration import/export apparatus  620  updates the configuration variable table  345  to complete the restore operation. In the case of a system administrator that fails to authenticate with the data password  550 , the save/restore configuration control apparatus  530  will refrain from sending any variables sets having encrypted data. 
     In the preferred embodiment, SNMP is used because of it common acceptance within the industry. However, an alternate embodiment would be as security improvement to encrypt the data password  550  with the SNMP set community name, and then use a secure transport such as secure sockets or the forthcoming SNMP II. 
     The persistent configuration text file  510  may be modified between save and restore times. Anyone who has edit access to the configuration file  510  can delete entries from the file. Anyone who has edit access to the configuration file  510  can add or modify public data. Private data can only be added by someone having edit access to the file who can also provide the correct data password  550 . For example, a second persistent configuration text file  510 ′ from a different server  600 ′ could be generated using the same data password  550  (which would result in the same encryption key). The user names/passwords from the second file  510 ′ could be imported/edited into the first configuration file  510 , and if restored with the proper data password  550 , the new records would also be imported to a target server  600 . 
     ALTERNATE EMBODIMENT 
     The preferred embodiment as show in FIG. 3 is based on the client server model where the functionality is split between a client computer and a server computer. An alternate embodiment is shown in FIG.  4 . In this embodiment, the invention is illustrated in a single device context. In this alternate embodiment, a single device configuration apparatus  526 , contained within the server management program  520 , replaces the client import/export apparatus  525  and the server configuration import/export apparatus  620  of FIG.  3  and operates on a configuration variable table  345  which generally is a software device that operates on the same computing device as the server management program  520 . Alternately, the configuration variable table  345  is contained with a discrete, separate device, connected to the device configuration import/export apparatus  526  through any standard computer connectivity mechanism such as serial port, a bus interface, a network, a parallel port, and infrared or other wireless connection and the like. 
     The preferred embodiment described herein is not intended to limit the scope of the invention as claimed, but rather is intended to teach those skilled in the art how to make and use the preferred embodiment of the claimed invention. The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics, thus the described embodiment is to be considered in all respects illustrative, not restrictive.