bill@videovax.Tek.COM (William K. McFadden) (11/30/88)
Does anybody have a callback program for 4.3 BSD? I would like to have the
VAX call me at home and allow me to login (instead of my dialing). Here's my
situation: Calling the VAX is a toll call, but the VAX can call me for free.
(Actually it's free for me right now; I want to change to metered phone service
to save money.) What I would like to do is call the VAX and tell it to wait a
minute and call me back. That way I only have to pay for the first minute.
Surely somebody has implemented something similar on their system. Can
anybody help with this? Thanks.
--
Bill McFadden Tektronix, Inc. P.O. Box 500 MS 58-639 Beaverton, OR 97077
UUCP: bill@videovax.Tek.COM, {hplabs,uw-beaver,decvax}!tektronix!videovax!bill
GTE: (503) 627-6920 Silliest new cartoon title: Teenage Mutant Ninja Turtlesrpw3@amdcad.AMD.COM (Rob Warnock) (12/02/88)
In article <5342@videovax.Tek.COM> bill@videovax.Tek.COM (William K. McFadden) writes: +--------------- | Does anybody have a callback program for 4.3 BSD? I would like to have the | VAX call me at home and allow me to login (instead of my dialing). Here's my | situation: Calling the VAX is a toll call, but the VAX can call me for free. | (Actually it's free for me right now; I want to change to metered phone... | to save money.) What I would like to do is call the VAX and tell it to wait a | minute and call me back. That way I only have to pay for the first minute. | Surely somebody has implemented something similar on their system. Can | anybody help with this? Thanks. +--------------- Attached below (since I've meant to for a long time) is the C program I use for *exactly* that purpose. It is a hack of a hack, and only works as it stands for Telebit Trailblazers, but has #ifdef's for a few others (Hayes & Practical Peripherals). (I know, I know, it should be a run-time decision...) To use, dial in to your host, log in, then say "callback <your-number>". It will hang up the phone, dial you back, and then prompt you for your login password. (You get three tries in 60 seconds to get it right.) NO WARRANTY, NO SUPPORT, but it's free... "It works for me." Known deficiencies: It waits a fixed amount of time (30 sec.) before assuming the callback should have completed, and prompting you for your password. If you use it over very long distance callbacks, you may need to jack this time up. On the other hand, very local users may wish to decrease it. (That's why there's source!) It was originally written by Jim Budler when he was at AMD (Thanks, Jim!), but I've hacked on it enough that all bugs are mine. Read the comments; read the code. I tried to document the problems I found (with modems, with 4.3) as I went along. Nota Bene: To avoid potentially locked-up modems or security problems (whether or not you use this program, incidentally), your modems *MUST* be configured to reset to NVRAM settings on DTR-down. Rob Warnock Systems Architecture Consultant UUCP: {amdcad,fortune,sun}!redwood!rpw3 ATTmail: !rpw3 DDD: (415)572-2607 USPS: 627 26th Ave, San Mateo, CA 94403 ============ attachment ====================================== /* * callback.c - sets tty nohang, noecho and ignore carrier, * then does call back and restores tty settings * * 860520 jimb@glc1 created * * 870410 rpw3@amdcad Modified to circumvent 4.3 conflict between carrier * and output (between hangup and re-dial). * * 880728 rpw3@amdcad Do password checking ourselves, rather than exec'ing * login. Lets you keep your same environment. If fail, * kill our parent shell, SIGHUP the process group, and * DTR-down the line. * (Bug? If parent is not top-level shell, can somebody * else can dial in? Maybe. How secure is SIGHUP?) */ #include <stdio.h> #include <signal.h> #include <sys/types.h> #include <sys/stat.h> #include <sgtty.h> #include <pwd.h> /* define exactly one of the following: */ /* #define PASSWORD /* uncomment for glc1 Password Modem */ /* #define HAYES /* uncomment for Hayes 1200 baud */ /* #define PPI /* Practical Peripherals Inc. 2400 baud */ #define TB /* Telebit TrailBlazer+ */ int parent; struct passwd *pw; main (argc,argv) int argc; char *argv[]; { int nohup = LNOHANG; int flushargs = 0; struct sgttyb ttystuff; int catcher(); if( argc != 2 ) { fprintf(stderr,"Usage: %s phone-number\n",argv[0]); exit(1); } parent = getppid(); if (parent <= 1) /* don't try to kill init */ parent = 0; pw = getpwuid(getuid()); if (!pw) { fprintf(stderr, "Can't get pw entry!\n"); exit(1); } if (!pw->pw_passwd) { fprintf(stderr, "Sorry, null password not allowed here!\n"); exit(1); } signal(SIGINT, SIG_IGN); /* turn off interrrupts */ signal(SIGQUIT, SIG_IGN); signal(SIGHUP, SIG_IGN); signal(SIGTSTP, SIG_IGN); signal(SIGTTIN, SIG_IGN); signal(SIGTTOU, SIG_IGN); setbuf(stdout,NULL); /* kill buffering */ ioctl( 0, TIOCGETP, &ttystuff); ttystuff.sg_flags &= (~ECHO); /* stty noecho */ ioctl( 0, TIOCSETP, &ttystuff); ioctl( 0, TIOCLBIS, &nohup); /* stty nohang */ #ifdef PASSWORD /* Password modem picky about timing */ sleep(2); printf("+++");sleep(2); /* send the "+++" */ printf("\r");sleep(1); printf("ATM0Q1DT %s\r",argv[1]); #else HAYES_or_PPI_or_TB sleep(4); printf("+++");sleep(4); /* send the "+++" */ /* With 4.3, must do it all in one cmd * to avoid the problem of not being * able to write if carrier is down. */ #ifdef HAYES printf("ATH,,,,,,DT%s\r",argv[1]); /* hangup, wait 12, re-dial */ #else PPI_or_TB /* Because the PPI and TB don't obey "," as a command (only as a dial * modifier), we have to break hangup/dialback into two commands. * To get around the 4.3 + carrier problem, we have to disable carrier- * detection between the commands. DZ-11's can't do this (the driver * is broken), so we can't use the ioctl. Solution: Tell the *modem* * to ignore carrier with &C0. Hazard: If we die in the middle, the * modem stays misconfigured. Safeguard: The PPI is configured &D3, * so when "login" times out and drops DTR, we'll get &C1 ("respect * carrier") back from the NVRAM. */ #ifdef TB printf("ATS53=0H\r",argv[1]); /* hangup, but with CD on */ #else PPI printf("AT&C0H\r",argv[1]); /* hangup, but with CD on */ #endif PPI sleep(6); /* wait for full hangup */ #ifdef TB printf("ATS53=3DT,,,%s\r",argv[1]); /* re-dial (normal CD) */ #else PPI printf("AT&C1DT,,,%s\r",argv[1]); /* re-dial (normal CD) */ #endif PPI #endif PPI_or_TB #endif not_PASSWORD sleep(30); /* wait until it's certain to have answered */ ioctl( 0, TIOCFLUSH, &flushargs); /* flush any garbage... */ ttystuff.sg_flags |= ECHO; /* stty echo */ ioctl( 0, TIOCSETP, &ttystuff); ioctl( 0, TIOCLBIC, &nohup); /* stty hang */ printf("\nWe're back!\007\n\n"); /* Hey, Yo! WAKE UP! */ signal(SIGINT, catcher); /* allow interrrupts */ signal(SIGHUP, catcher); signal(SIGQUIT, catcher); alarm(0); signal(SIGALRM, catcher); alarm(60); /* time, but not TOO much */ if (checkpass()) /* verify same guy */ catcher(); /* no? then die, scum! */ exit(0); } catcher() { ioctl( 0, TIOCCDTR, 0); /* hang up the phone */ if (parent > 1) kill(parent, SIGHUP); kill(0, SIGHUP); _exit(0); } int checkpass() { int i; extern char *crypt(), *getpass(); char *pass, *pass2; for (i = 0; i < 3; ++i) { pass = getpass("Password: "); pass2 = crypt(pass, pw->pw_passwd); if (strcmp(pass2, pw->pw_passwd) == 0) return 0; } return -1; }