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diff --git a/mdk-stage1/ppp/README.MSCHAP80 b/mdk-stage1/ppp/README.MSCHAP80 deleted file mode 100644 index d3ed291b7..000000000 --- a/mdk-stage1/ppp/README.MSCHAP80 +++ /dev/null @@ -1,284 +0,0 @@ -PPP Client Support for Microsoft's CHAP-80 -========================================== - -Eric Rosenquist rosenqui@strataware.com -(updated by Paul Mackerras) -(updated by Al Longyear) -(updated by Farrell Woods) - -INTRODUCTION - -Microsoft has introduced an extension to the Challenge/Handshake -Authentication Protocol (CHAP) which avoids storing cleartext -passwords on a server. (Unfortunately, this is not as secure as it -sounds, because the encrypted password stored on a server can be used -by a bogus client to gain access to the server just as easily as if -the password were stored in cleartext.) The details of the Microsoft -extensions can be found in the document: - - <ftp://ftp.microsoft.com/developr/rfc/chapexts.txt> - -In short, MS-CHAP is identified as <auth chap 80> since the hex value -of 80 is used to designate Microsoft's scheme. Standard PPP CHAP uses -a value of 5. If you enable PPP debugging with the "debug" option and -see something like the following in your logs, the remote server is -requesting MS-CHAP: - - rcvd [LCP ConfReq id=0x2 <asyncmap 0x0> <auth chap 80> <magic 0x46a3>] - ^^^^^^^^^^^^ - -The standard pppd implementation will indicate its lack of support for -MS-CHAP by NAKing it: - - sent [LCP ConfNak id=0x2 <auth chap 05>] - -Windows NT Server systems are often configured to "Accept only -Microsoft Authentication" (this is intended to enhance security). Up -until now, that meant that you couldn't use this version of PPPD to -connect to such a system. I've managed to get a client-only -implementation of MS-CHAP working; it will authenticate itself to -another system using MS-CHAP, but if you're using PPPD as a dial-in -server, you won't be able to use MS-CHAP to authenticate the clients. -This would not be a lot of extra work given that the framework is in -place, but I didn't need it myself so I didn't implement it. - - -BUILDING THE PPPD - -MS-CHAP uses a combination of MD4 hashing and DES encryption for -authentication. You may need to get Eric Young's libdes library in -order to use my MS-CHAP extensions. A lot of UNIX systems already -have DES encryption available via the crypt(3), encrypt(3) and -setkey(3) interfaces. Some may (such as that on Digital UNIX) -provide only the encryption mechanism and will not perform -decryption. This is okay. We only need to encrypt to perform -MS-CHAP authentication. - -If you have encrypt/setkey available, then hopefully you need only -define these two things in your Makefile: -DUSE_CRYPT and -DCHAPMS. -Skip the paragraphs below about obtaining and building libdes. Do -the "make clean" and "make" as described below. Linux users -should not need to modify their Makefiles. Instead, -just do "make CHAPMS=1 USE_CRYPT=1". - -If you don't have encrypt and setkey, you will need Eric Young's -libdes library. You can find it in: - -ftp://ftp.funet.fi/pub/crypt/mirrors/ftp.psy.uq.oz.au/DES/libdes-3.06.tar.gz - -Australian residents can get libdes from Eric Young's site: - -ftp://ftp.psy.uq.oz.au/pub/Crypto/DES/libdes-3.06.tar.gz - -It is also available on many other sites (ask Archie). - -I used libdes-3.06, but hopefully anything newer than that will work -also. Get the library, build and test it on your system, and install -it somewhere (typically /usr/local/lib and /usr/local/include). - - - -You should now be ready to (re)compile the PPPD. Go to the pppd -subdirectory and make sure the Makefile contains "-DCHAPMS" in the -CFLAGS or COMPILE_FLAGS macro, and that the LIBS macro (or LDADD for -BSD systems) contains "-ldes". Depending on your system and where the -DES library was installed, you may also need to alter the include and -library paths used by your compiler. - -Do a "make clean" and then a "make" to rebuild pppd. Assuming all -goes well, install the new pppd and move on to the CONFIGURATION -section. - - -CONFIGURATION - -If you've never used PPPD with CHAP before, read the man page (type -"man pppd") and read the description in there. Basically, you need to -edit the "chap-secrets" file typically named /etc/ppp/chap-secrets. -This should contain the following two lines for each system with which -you use CHAP (with no leading blanks): - - RemoteHost Account Secret - Account RemoteHost Secret - -Note that you need both lines and that item 1 and 2 are swapped in the -second line. I'm not sure why you need it twice, but it works and I didn't -have time to look into it further. The "RemoteHost" is a somewhat -arbitrary name for the remote Windows NT system you're dialing. It doesn't -have to match the NT system's name, but it *does* have to match what you -use with the "remotename" parameter. The "Account" is the Windows NT -account name you have been told to use when dialing, and the "Secret" is -the password for that account. For example, if your service provider calls -their machine "DialupNT" and tells you your account and password are -"customer47" and "foobar", add the following to your chap-secrets file: - - DialupNT customer47 foobar - customer47 DialupNT foobar - -The only other thing you need to do for MS-CHAP (compared to normal CHAP) -is to always use the "remotename" option, either on the command line or in -your "options" file (see the pppd man page for details). In the case of -the above example, you would need to use the following command line: - - pppd name customer47 remotename DialupNT <other options> - -or add: - - name customer47 - remotename DialupNT - -to your PPPD "options" file. - -The "remotename" option is required for MS-CHAP since Microsoft PPP servers -don't send their system name in the CHAP challenge packet. - - -E=691 (AUTHENTICATION_FAILURE) ERRORS WHEN YOU HAVE THE VALID SECRET (PASSWORD) - -If your RAS server is not the domain controller and is not a 'stand-alone' -server then it must make a query to the domain controller for your domain. - -You need to specify the domain name with the user name when you attempt to -use this type of a configuration. The domain name is specified with the -local name in the chap-secrets file and with the option for the 'name' -parameter. - -For example, the previous example would become: - - DialupNT domain\\customer47 foobar - domain\\customer47 DialupNT foobar - -and - - pppd name 'domain\\customer47' remotename DialupNT <other options> - -or add: - - name domain\\customer47 - remotename DialupNT - -when the Windows NT domain name is simply called 'domain'. - - -TROUBLESHOOTING - -Assuming that everything else has been configured correctly for PPP and -CHAP, the MS-CHAP-specific problems you're likely to encounter are mostly -related to your Windows NT account and its settings. A Microsoft server -returns error codes in its CHAP response. The following are extracted from -Microsoft's "chapexts.txt" file referenced above: - - 646 ERROR_RESTRICTED_LOGON_HOURS - 647 ERROR_ACCT_DISABLED - 648 ERROR_PASSWD_EXPIRED - 649 ERROR_NO_DIALIN_PERMISSION - 691 ERROR_AUTHENTICATION_FAILURE - 709 ERROR_CHANGING_PASSWORD - -You'll see these in your pppd log as a line similar to: - - Remote message: E=649 R=0 - -The "E=" is the error number from the table above, and the "R=" flag -indicates whether the error is transient and the client should retry. If -you consistently get error 691, then either you're using the wrong account -name/password, or the DES library or MD4 hashing (in md4.c) aren't working -properly. Verify your account name and password (use a Windows NT or -Windows 95 system to dial-in if you have one available). If that checks -out, test the DES library with the "destest" program included with the DES -library. If DES checks out, the md4.c routines are probably failing -(system byte ordering may be a problem) or my code is screwing up. I've -only got access to a Linux system, so you're on your own for anything else. - -Another thing that might cause problems is that some RAS servers won't -respond at all to LCP config requests without seeing the word "CLIENT" -from the other end. If you see pppd sending out LCP config requests -without getting any reply, try putting something in your chat script -to send the word CLIENT after the modem has connected. - -If everything compiles cleanly, but fails at authentication time, then -it might be a case of the MD4 or DES code screwing up. The following -small program can be used to test the MS-CHAP code to see if it -produces a known response: - ------------------ -#include <stdio.h> - -#include "pppd.h" -#include "chap.h" -#include "chap_ms.h" - -int main(argc, argv) - int argc; - char *argv[]; -{ - u_char challenge[8]; - int challengeInt[sizeof(challenge)]; - chap_state cstate; - int i; - - if (argc != 3) { - fprintf(stderr, "Usage: %s <16-hexchar challenge> <password>\n", - argv[0]); exit(1); - } - - sscanf(argv[1], "%2x%2x%2x%2x%2x%2x%2x%2x", - challengeInt + 0, challengeInt + 1, challengeInt + 2, - challengeInt + 3, challengeInt + 4, challengeInt + 5, - challengeInt + 6, challengeInt + 7); - - for (i = 0; i < sizeof(challenge); i++) - challenge[i] = (u_char)challengeInt[i]; - - ChapMS(&cstate, challenge, sizeof(challenge), argv[2], strlen(argv[2])); - printf("Response length is %d, response is:", cstate.resp_length); - - for (i = 0; i < cstate.resp_length; i++) { - if (i % 8 == 0) - putchar('\n'); - printf("%02X ", (unsigned int)cstate.response[i]); - } - - putchar('\n'); - - exit(0); -} -------------- - -This needs to link against chap_ms.o, md4.o, and the DES library. When -you run it with the command line: - - $ testchap 00000000000000000000000000000000 hello - -it should output the following: - - Response length is 49, response is: - 00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00 - F4 D9 9D AF 82 64 DC 3C - 53 F9 BC 92 14 B5 5D 9E - 78 C4 21 48 9D B7 A8 B4 - 01 - -if not, then either the DES library is not working, the MD4 code isn't -working, or there are some problems with the port of the code in -chap_ms.c. - - -STILL TO DO - -A site using only MS-CHAP to authenticate has no need to store cleartext -passwords in the "chap-secrets" file. A utility that spits out the ASCII -hex MD4 hash of a given password would be nice, and would allow that hash -to be used in chap-secrets in place of the password. The code to do this -could quite easily be lifted from chap_ms.c (you have to convert the -password to Unicode before hashing it). The chap_ms.c file would also have -to be changed to recognize a password hash (16 binary bytes == 32 ASCII hex -characters) and skip the hashing stage. - -A server implementation would allow MS-CHAP to be used with Windows NT and -Windows 95 clients for enhanced security. Some new command-line options -would be required, as would code to generate the Challenge packet and -verify the response. Most of the helper functions are in place, so this -shouldn't be too hard for someone to add. |