Mark Ryden writes:
> Is there a way from user space to know which device is the one which
> the ppp connection uses ?
Yes, that information is in the tdb database (/var/run/pppd2.tdb).
As an example, here is the list of records in /var/run/pppd2.tdb for
my gateway machine (IP addresses obscured):
DEVICE=eth0: pppd2480
IPREMOTE=xx.xx.xx.xx: pppd2480
IFNAME=ppp0: pppd2480
pppd2480: ORIG_UID=0;PPPD_PID=2483;PPPLOGNAME=root;DEVICE=eth0;LINKNAME=transact;IPLOCAL=yy.yy.yy.yy;IPREMOTE=xx.xx.xx.xx;IFNAME=ppp0
LINKNAME=transact: pppd2480
PPPD_PID=2483: pppd2480
That is for one connection.
Below is the source for the little "tdbdump" program that I used to
print the above. It needs to be linked with pppd/tdb.o and
pppd/spinlock.o.
It wouldn't be hard to write a program to use the lookup routines
in pppd/tdb.c and extract the underlying device for a given ppp
interface.
Paul.
#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/time.h>
#include "tdb.h"
static int print_rec(TDB_CONTEXT *tdb, TDB_DATA key, TDB_DATA dbuf, void *p)
{
printf("%*.*s: %*.*s\n",
(int)key.dsize, (int)key.dsize, key.dptr,
(int)dbuf.dsize, (int)dbuf.dsize, dbuf.dptr);
return 0;
}
main(int ac, char **av)
{
TDB_CONTEXT *tdb;
if (ac != 2) {
fprintf(stderr, "Usage: %s database\n", av[0]);
exit(1);
}
tdb = tdb_open(av[1], 0, 0, O_RDONLY, 0600);
if (tdb == 0) {
perror(av[1]);
exit(1);
}
tdb_traverse(tdb, print_rec, NULL);
exit(0);
}
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