🚀 go-pugleaf

[This is a followup to an article in comp.lang.perl.  comp.mail.misc is
probably not the right place for it, either, but it doesn't seem too
unreasonable.]

In article <126122@uunet.UU.NET>, rbj@uunet.UU.NET (Root Boy Jim) writes:
> Distribution: usa
Hmm.  Some of us outside the USA arrange to get these articles anyway.

> That number is for UUCP only, not kermit. We do plan on making
> anonymous kermit available sometime in the future.

Then you might be interested in my anonymous kermit setup.  It is not
very well tested, and I cannot guarantee that there are no security
holes.

Extracts from /etc/passwd:

ftp:*:25:100:,anonymous ftp:/usr/ftp/anon:/bin/false
kermit::27:100:,anonymous kermit:/usr/ftp/anon:/usr/local/bin/anon-kermit

I am appending a shar of the anon-kermit program itself, and the
kermit.rc file that I install in the etc directory below the
anonymous-ftp chroot directory.

I wanted to write this in perl, but get a compliant about "you haven't
disabled suid scripts in your kernel" or something like that.  How can
I disable suid scripts? (HP-UX 7.0 on an hp9000 series 300)

--apb
Alan Barrett, Dept. of Electronic Eng., Univ. of Natal, Durban, South Africa
Internet: barrett@ee.und.ac.za           UUCP: m2xenix!quagga!undeed!barrett

# This is a shell archive.  Remove anything before this line,
# then unpack it by saving it in a file and typing "sh file".
#
# Wrapped by Alan P Barrett <barrett@undeed> on Tue Mar 26 12:55:19 1991
#
# This archive contains:
#	anon-kermit.c	kermit.rc
#

LANG=""; export LANG
PATH=/bin:/usr/bin:$PATH; export PATH

echo x - anon-kermit.c
cat >anon-kermit.c <<'@EOF'
/* @(#)anon-kermit.c 1.1 91/03/26 */
/* anon-kermit.c
 * A P Barrett, Feb 1991
 *
 * Intended as the login shell for an anonymous-kermit account,
 * which will have access to the anonymous-ftp directory.
 *
 * What this program does:
 * 1. chdir() and chroot() to the anonymous ftp directory.
 * 2. setgid() and setuid() to the anonymous ftp user id.
 * 3. exec kermit, with options that tell it to read the startup
 *    file in /etc/kermit.rc.
 *
 * Other requirements:
 * 1. /etc/passwd must contain a dummy entry for a user named 'ftp'.
 *    The uid and gid fields must be something harmless.  The home
 *    directory must be the root of the anonymous ftp area.  (The
 *    ftp server probbaly requires exactly the same thing in the
 *    /etc/passwd file).
 * 2. The chroot()ed filesystem used by anonymous ftp must contain
 *    the following files:
 *    a.  /bin/kermit (the kermit program)
 *    b.  /etc/kermit.rc (startup file for kermit)
 *    c.  /dev/tty (must have same major and minor numbers as the
 *        real /dev/tty in the root filesystem)
 *    d.  /bin/sh (for kermit to execute various commands)
 *    e.  /bin/ls (for directory listings)
 *    f.  /bin/rm (for deleting files through kermit) (optional)
 * 3. This program must be suid-root
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <pwd.h>

int main (argc, argv)
    int argc;
    char **argv;
{
    struct passwd *ftp_pw;

    /* get info from dummy 'ftp' entry in passwd file.
     * we are interested in uid, gid and home directory
     */
    if ((ftp_pw = getpwnam ("ftp")) == NULL) {
	(void) fprintf (stderr, "%s: cannot get user information\n", argv[0]);
	exit (1);
    }

    /* tidy environment
     */
    if (putenv ("PATH=/bin") != 0 ||
	putenv ("SHELL=/bin/sh") != 0 ||
	putenv ("IFS= \t\f") != 0 ||
	putenv ("HOME=/") != 0)
    {
	(void) fprintf (stderr, "%s: cannot set environment\n", argv[0]);
	exit (1);
    }

    /* chroot to the correct directory
     */
    if (chdir (ftp_pw->pw_dir) != 0 || chroot (".") != 0) {
	(void) fprintf (stderr, "%s: cannot chdir or chroot\n", argv[0]);
	exit (1);
    }

    /* set uid/gid to the anon ftp user
     */
    if (setgid (ftp_pw->pw_gid) != 0 || setuid (ftp_pw->pw_uid) != 0) {
	(void) fprintf (stderr, "%s: cannot setgid or setuid\n", argv[0]);
	exit (1);
    }

    (void) execl ("/bin/kermit", "anon-kermit",
		"-y", "/etc/kermit.rc", "-x", (char *) 0);
    /* if we get here */ {
	(void) fprintf (stderr, "%s: cannot run kermit\n", argv[0]);
	exit (1);
    }
}
@EOF

chmod 444 anon-kermit.c

echo x - kermit.rc
cat >kermit.rc <<'@EOF'
disable host
disable who
# disable delete	# why bother? ftp allows delete
@EOF

chmod 444 kermit.rc

exit 0