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For now, I am working around this issue by telling dhcpd not to fork
(-f option) and instead forking the shell (append ' &' to the
command line).<br>
<br>
On 1/6/2020 2:02 PM, Jay Foster wrote:<br>
<blockquote type="cite"
cite="mid:3c80ee93-be84-785d-07cc-c2e1b4995b94@systech.com">
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dhcpd is running as root whether or not it forks (evidenced by
ps). I do not see how forking or not forking has any bearing on
permissions. dhcpd does not report any errors writing the leases
file (daemon.info dhcpd: Wrote 1 leases to leases file.).<br>
<br>
For grins, I chown dhcp:dhcp both the leases file and .conf file.
Makes no difference. Also tried adding '-user dhcp -group dhcp'.
Also makes no difference.<br>
<br>
There is no evidence of any kind of a permissions issue. strace
shows that dhcpd creates 3 child processes via clone(2). These
processes seem to be associated with the dhcp_context_create(),
omapi_init(), etc. function calls. In the forking case, these get
terminated along with the parent process after the fork(2), but
obviously do not when not forking. That is the only difference
that I see between the forking and non-forking invocations.<br>
<br>
<div class="moz-cite-prefix">On 1/6/2020 1:49 PM, Christopher
Barry wrote:<br>
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cite="mid:CAOajpmq43V72OCZ8bvNmE9jiAHQo6qofFNb61E9+=14iCPKYUQ@mail.gmail.com">
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<div dir="auto">Generally, when backgrounded, dhcpd runs with
reduced privs, e.g. as dhcpd:dhcpd (your configured user/group
may be different). Can you su as that user and run dhcpd in
the foreground? I'm suspecting that user may not have write
perms to the leases file.
<div dir="auto"><br>
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<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Mon, Jan 6, 2020, 4:15 PM
Jay Foster <<a href="mailto:jay@systech.com"
moz-do-not-send="true">jay@systech.com</a>> wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF"> Can you be more
specific? /usr/sbin/dhcpd is root:root. /usr/sbin/dhcpd
is being run as root.<br>
<br>
<div>On 1/6/2020 12:58 PM, Christopher Barry wrote:<br>
</div>
<blockquote type="cite">
<div dir="auto">Make sure user/group perms are valid.
<div dir="auto"><br>
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<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Mon, Jan 6, 2020,
1:42 PM Jay Foster <<a
href="mailto:jay@systech.com" target="_blank"
rel="noreferrer" moz-do-not-send="true">jay@systech.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">I
am using the ISC DHCP server (dhcpd) version 4.3.6
from a rocko Yocto <br>
build. When dhcpd is started without the '-f' or
'-d' options (forks to <br>
the background) it does not work. DHCP DISCOVER
requests are sent, but <br>
the dhcpd application does not respond. I can
attach strace to the <br>
dhcpd process and see that dhcpd just sleeps in an
futex() call.<br>
<br>
If I start dhcpd with either the '-f' or '-d'
options so it does not <br>
fork, then it works properly.<br>
<br>
I have run dhcpd (both forking and non forking)
using strace to see if I <br>
could spot any differences. The only thing I notice
is that when <br>
forking, the parent process terminates (expected)
along with 3 other <br>
child processes/threads. It looks like these other
threads are supposed <br>
to handle the ISC tasks/messages, but are not cloned
by the fork and are <br>
not present after forking.<br>
<br>
For reference, with an older version of ISC DHCP
server (4.1.1-P1) on an <br>
older product, this problem does not occur.<br>
<br>
Any ideas where to look?<br>
<br>
<br>
<br>
<br>
<br>
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