Small embedded system, need working ntpd...

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I have a small embedded system (pc/104 board, CF-boot, read-only root
file system, etc).  I am trying to get a ntp daemon to work to keep the
time accurate.  I downloaded and compiled (on the same hardware but
booting off a HD, which has more space, and is a 'normal' gentoo
system) openntpd (, however I am having trouble
getting it to work.

There seems to be almost no documentation with it, nothing that really
explains how to get it to work.

I ran the file (./ntpd) and it said it couldn't find a file,
/etc/ntpd.conf, I then created that file, then ran it again, now it
says "unknown user _ntp". I have a "_ntp" user and a "ntp" user (one of
my linux gurus said it would not be _ntp, another said it would be
_ntp, so I'm confused).  In either case it doesn't work, gives me the
"unknown user _ntp" and that's as far as I get.

Anyone used this ntpd, and if not, anyone have another simple, small
ntpd I could throw into this project.

Mark Brodis

Re: Small embedded system, need working ntpd...
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Someone else emailed me about that today, also for an embedded system.
(The "make install" process normally takes care of most installation
tasks on self-hosted systems).  The doco has been updated in the latest
snapshot with the details (see the INSTALL file):

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It defaults to "_ntp" unless you overrode it at configure time with

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It's possible that the problem isn't in ntpd itself, eg if your flash
filesystem is missing some of the components required for the getpwnam()
function to work (eg /etc/nsswitch.conf or the libnss*.so files if
you're using glibc).

Try the test program at the bottom of this post.  If that doesn't work
either then you need to take a closer look at your system.

$ ./a.out _ntp
home dir = /var/empty/ntpd
$ ./a.out root
home dir = /root

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Well, it works for me :-)  I have used it on an embedded Linux firewall/
router (300MHz Geode, 64MB RAM, 2.4 kernel, uClibc, busybox plus assorted
other stuff).

[example program]
#include <stdio.h>
#include <sys/types.h>
#include <pwd.h>

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

        if (argc != 2) {
                printf("usage: %s username\n", argv[0]);
        pw = getpwnam(argv[1]);
        if (pw == NULL)
                printf("getpwnam failed\n");
                printf("home dir = %s\n", pw->pw_dir);

Darren Tucker (dtucker at
GPG key 8FF4FA69 / D9A3 86E9 7EEE AF4B B2D4  37C9 C982 80C7 8FF4 FA69
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Re: Small embedded system, need working ntpd...
Thanks for your response!

I had already figured out the majority of the problems, it was with
some library conflicts....doh!!  Once that was resolved, and I got some
help from a brilliant embedded Linux guy, all fell into place...  :)

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