Winstar says there is no TCP/BGP vulnerability

Wed Apr 21 04:51:06 UTC 2004

Patrick / Christopher,

>> Michel Py wrote:
>> Please forgive me if I'm naive and/or ask a stupid question,
>> but is there any reason (besides your platform not supporting
>> it) _not_ to MD5 your BGP sessions? Geez, on my _home_ router
>> all my v4 BGP sessions are MD5ed (v6 not there yet).

> Patrick W.Gilmore wrote:
> There is serious operational overhead in maintaining sync'ed
> passwords between separate organizations.  IOW: Eventually
> someone will screw up and lose the password.
> [large snip]

Thanks for the insight. I have an even dumber question:

Context: set aside the MD5, the way I configure BGP sessions/traffic
from/to peers is as follows:

a) A generic (configured in the peer-group) route-map to filter the
routes I announce to the peer to be only my blocks.

b) A specific-to-the-peer route-map to filter the routes I receive from
the peer to the peer's blocks, as agreed in the beer drinking meeting
^H^H^H^H BLPA. This route map is not entirely specific, as I also put in
stuff such as deny RFC1918 routes ;-)

c) A generic access-list filtering ingress traffic from the peer to me
to allow only traffic which DA is mine. (cracks me up if the peer sets a
default to me :-)

d) A generic access-list filtering egress traffic from me to the peer to
allow only traffic which SA is mine.

Now, the dumb question:
Given:
1) The context above especially item b
2) Christopher Morrow's comments below
Explain me what having or not having the MD5 password changes. Either
you're small and/or stupid and do it manually, or you have an automated
system that does it for you.

> Christopher L. Morrow wrote:
> there is the issue of changing the keys during operations
> without impacting the network, eh? Having to bounce every
> bgp session in your network can be pretty darned painful...
> if you change the key(s) of course.

See above: Changing the route-map is equally painful.

> If you don't you might as well not have keys, since adding
> the 3 lines of C code required to Paul Watsons' program
> making it do the hashing certainly won't be a big deal, eh?

I'm weak with C. Besides adding "neighbor x.x.x.x password 7 " below
"enable-password 7 " for each peer (which requires recompiling, how
annoying) would you care sharing the 3 said lines for the code below :-)

Michel.

#include <stdio.h>
#include <ctype.h>

char xlat[] = {
        0x64, 0x73, 0x66, 0x64, 0x3b, 0x6b, 0x66, 0x6f,
        0x41, 0x2c, 0x2e, 0x69, 0x79, 0x65, 0x77, 0x72,
        0x6b, 0x6c, 0x64, 0x4a, 0x4b, 0x44
};

char pw_str1[] = "password 7 ";
char pw_str2[] = "enable-password 7 ";

char *pname;

cdecrypt(enc_pw, dec_pw)
char *enc_pw;
char *dec_pw;
{
        unsigned int seed, i, val = 0;

        if(strlen(enc_pw) & 1)
                return(-1);

        seed = (enc_pw[0] - '0') * 10 + enc_pw[1] - '0';

        if (seed > 15 || !isdigit(enc_pw[0]) || !isdigit(enc_pw[1]))
                return(-1);

        for (i = 2 ; i <= strlen(enc_pw); i++) {
                if(i !=2 && !(i & 1)) {
                        dec_pw[i / 2 - 2] = val ^ xlat[seed++];
                        val = 0;
                }

                val *= 16;

                if(isdigit(enc_pw[i] = toupper(enc_pw[i]))) {
                        val += enc_pw[i] - '0';
                        continue;
                }

                if(enc_pw[i] >= 'A' && enc_pw[i] <= 'F') {
                        val += enc_pw[i] - 'A' + 10;
                        continue;
                }

                if(strlen(enc_pw) != i)
                        return(-1);
        }                       

        dec_pw[++i / 2] = 0;

        return(0);
}

usage()
{
        fprintf(stdout, "Usage: %s -p <encrypted password>\n", pname);
        fprintf(stdout, "       %s <router config file> <output
file>\n", pname);

        return(0);
}

main(argc,argv)
int argc;
char **argv;

{
        FILE *in = stdin, *out = stdout;
        char line[257];
        char passwd[65];
        unsigned int i, pw_pos;

        pname = argv[0];

        if(argc > 1)
        {
                if(argc > 3) {
                        usage();
                        exit(1);
                }

                if(argv[1][0] == '-')
                {
                        switch(argv[1][1]) {
                                case 'h':
                                usage();
                                break;

                                case 'p':
                                if(cdecrypt(argv[2], passwd)) {
                                        fprintf(stderr, "Error.\n");
                                        exit(1);
                                }
                                fprintf(stdout, "password: %s\n",
passwd);
                                break;

                                default:
                                fprintf(stderr, "%s: unknow option.",
pname);
                        }

                        return(0);
                }

                if((in = fopen(argv[1], "rt")) == NULL)
                        exit(1);
                if(argc > 2)
                        if((out = fopen(argv[2], "wt")) == NULL)
                                exit(1);
        }

        while(1) {
                for(i = 0; i < 256; i++) {
                        if((line[i] = fgetc(in)) == EOF) {
                                if(i)
                                        break;

                                fclose(in);
                                fclose(out);
                                return(0);
                        }
                        if(line[i] == '\r')
                                i--;

                        if(line[i] == '\n')
                                break;
                }
                pw_pos = 0;
                line[i] = 0;

                if(!strncmp(line, pw_str1, strlen(pw_str1)))
                        pw_pos = strlen(pw_str1);

                if(!strncmp(line, pw_str2, strlen(pw_str2)))
                        pw_pos = strlen(pw_str2);

                if(!pw_pos) {
                        fprintf(stdout, "%s\n", line);
                        continue;
                }

                if(cdecrypt(&line[pw_pos], passwd)) {
                        fprintf(stderr, "Error.\n");
                        exit(1);
                }
                else {
                        if(pw_pos == strlen(pw_str1))
                                fprintf(out, "%s", pw_str1);
                        else
                                fprintf(out, "%s", pw_str2);

                        fprintf(out, "%s\n", passwd);
                }
        }
}