dhcpd-4.2.2 maxsocks problem
Jeff Waller
jeffw at cnxntech.com
Thu Jan 12 18:53:08 UTC 2012
Hmm,
Looks like the variable values are missing...
could you do
up
up
up
list
I have a feeling that wont work because you missing the source code.
So, I think you're going to need to get the source and compile it. There is a option to configure that
allows you to compile DHCPd for debugging. Do that, I think it would be
get source
unpack source
read install instructions but this will be something like
configure --enable-debug
make
you don't even need to install this yet because you'll debug it from the source directory
I do not know the arguments that need to be used to start the dhcp server on your particular system, but
you'll need to know these
here's an example, but, again, you'll need to know how yours is different
dhcpd -lf /usr/local/dhcpd/dhcpd.leases -cf /usr/local/dhcpd/dhcpd.conf eth0
Once you know this, then you can use that same information using gdb.
In the source directory for dhcp, when the dhcp server is compiled, it is placed in the subdirectory server
so cd to that and then do
gdb dhcpd
at the gdb prompt type
break assertions.c:58 (because that's where it died in the stack trace before). However, if you get the
latest source, then maybe version 4.2.3 will have that particular statement on a different line then 4.2.2
so maybe break assertions.c:58 is wrong and instead you'll need another number -- comparing the source
code and check what line number each is on will suffice.
this will catch the server and stop it just before it kills the process with abort
then type
run <but with the arguments to dhcp you found out before> so in my example above (but again yours
may be different)
run -lf /usr/local/dhcpd/dhcpd.leases -cf /usr/local/dhcpd/dhcpd.conf eth0
and then the server will attempt to start up and hit the error you found and the reach that section that it
was just about to kill itself, but not yet because gdb stopped it first and then at that point you can type
where
up
print fd
Then tell us what fd is.
On Jan 12, 2012, at 12:54 PM, Jan Markus wrote:
> Dne 01/12/2012 04:38 PM, Jeff Waller napsal(a):
>> Without looking into the code too much I found the following comment in socket.c (see below): Which I think
>> means yea you can change the kernel to allow more file descriptors but you will run into problems
>> trying to increase beyond either 4096 or FD_SETSIZE whichever is applicable depending on how
>> the server was compiled. It appears you can change that number maybe and re-compile but
>> be wary.
>>
>> Here's what FD_SETSIZE is set to in linux:
>>
>> ./linux/posix_types.h:#define __FD_SETSIZE 1024
>>
>>
>>
>> Couple of things to try.
>>
>> 1) First off, what is that number? Is it 1024 or is it 4096? Use gdb to find out where this is hitting the error.
>> It maybe be as simple as gdb dhcpd core (modify to actual filenames if not all in the same
>> directory).
>
> Oh, one more thing, it will be of any help:
>
>
> #0 0x00000008009d1fcc in kill () from /lib/libc.so.7
> (gdb) bt
> #0 0x00000008009d1fcc in kill () from /lib/libc.so.7
> #1 0x00000008009d0dcb in abort () from /lib/libc.so.7
> #2 0x000000000052b71f in isc_assertion_failed (file=Variable "file" is not available.
> ) at ../../../lib/isc/assertions.c:58
> #3 0x000000000054872b in select_poke (manager=0x157cc, fd=Variable "fd" is not available.
> ) at ../../../../lib/isc/unix/socket.c:959
> #4 0x000000000054a013 in isc__socket_fdwatchcreate (manager0=0x800c69000, fd=1024, flags=1,
> callback=0x46e930 <omapi_iscsock_cb>, cbarg=0x801908460, task=0x800c6e000, socketp=0x8019084b0)
> at ../../../../lib/isc/unix/socket.c:2699
> #5 0x0000000000470340 in omapi_register_io_object (h=0x8011d0f00, readfd=0x444860 <if_readsocket>,
> writefd=0,
> reader=0x4452c0 <got_one>, writer=0, reaper=0) at dispatch.c:259
> #6 0x0000000000445e9b in discover_interfaces (state=1) at discover.c:1289
> #7 0x000000000040de69 in main (argc=Variable "argc" is not available.
> ) at dhcpd.c:709
> (gdb)
>
> -Jan
>
>
>>
>> 2) Get 4.2.3 (4.2.2 is 6 months old). I would have thought that you can simply download the
>> source and compile, it doesn't compile on BSD?? If you're going to modify, you're going to need
>> the source anyway. And figure out a way to not use SELECT there is definitely support for
>> this in configure but it looks like kqueue on by default; make sure. BTW this is all bind stuff which
>> dhcp depends on
>>
>> ./configure --help
>>
>> ....
>>
>> --enable-kqueue use BSD kqueue when available [default=yes]
>> --enable-epoll use Linux epoll when available [default=auto]
>> --enable-devpoll use /dev/poll when available [default=yes]
>>
>> ...
>>
>>
>> ==================================================================================
>> /*%
>> * Maximum number of allowable open sockets. This is also the maximum
>> * allowable socket file descriptor.
>> *
>> * Care should be taken before modifying this value for select():
>> * The API standard doesn't ensure select() accept more than (the system default
>> * of) FD_SETSIZE descriptors, and the default size should in fact be fine in
>> * the vast majority of cases. This constant should therefore be increased only
>> * when absolutely necessary and possible, i.e., the server is exhausting all
>> * available file descriptors (up to FD_SETSIZE) and the select() function
>> * and FD_xxx macros support larger values than FD_SETSIZE (which may not
>> * always by true, but we keep using some of them to ensure as much
>> * portability as possible). Note also that overall server performance
>> * may be rather worsened with a larger value of this constant due to
>> * inherent scalability problems of select().
>> *
>> * As a special note, this value shouldn't have to be touched if
>> * this is a build for an authoritative only DNS server.
>> */
>> #ifndef ISC_SOCKET_MAXSOCKETS
>> #if defined(USE_KQUEUE) || defined(USE_EPOLL) || defined(USE_DEVPOLL)
>> #define ISC_SOCKET_MAXSOCKETS 4096
>> #elif defined(USE_SELECT)
>> #define ISC_SOCKET_MAXSOCKETS FD_SETSIZE
>> #endif /* USE_KQUEUE... */
>> #endif /* ISC_SOCKET_MAXSOCKETS */
>> ==================================================================================
>>
>>
>>
>>
>> On Jan 12, 2012, at 8:51 AM, Jan Markus wrote:
>>
>>> Hello,
>>>
>>> we have isc-dhcpd 4.2.2 from ports on FreeBSD 8.2. We have cca 1050 Vlan interfaces:
>>>
>>>
>>> ifconfig vlan1234 create inet 10.0.0.1/29 vlan 1234 vlandev igb1
>>>
>>>
>>> and the same number of dhcpd declarations like this:
>>>
>>> shared-network vlan1234 {
>>> subnet 10.0.0.0 netmask 255.255.255.248 {
>>> range 10.0.0.2 10.0.0.5;
>>> option routers 10.0.0.1;
>>> }
>>> }
>>>
>>> But our DHCP server refuses to start, saying:
>>>
>>> ../../../../lib/isc/unix/socket.c:958: INSIST(fd>= 0&& fd< (int)manager->maxsocks) failed, back trace
>>> #0 0x52a5ca in ??
>>> #1 0x52a77a in ??
>>> #2 0x54768b in ??
>>> #3 0x548f63 in ??
>>> #4 0x46fc80 in ??
>>> #5 0x445cfb in ??
>>> #6 0x40de69 in ??
>>> #7 0x40c38e in ??
>>> #8 0x8006bc000 in ??
>>> Abort trap (core dumped)
>>> /usr/local/etc/rc.d/isc-dhcpd: WARNING: failed to start dhcpd
>>>
>>> My kernel sockets limits are:
>>>
>>> # sysctl -a | grep soc
>>> kern.ipc.maxsockbuf: 16777216
>>> kern.ipc.maxsockets: 204800
>>> kern.ipc.numopensockets: 17
>>> net.inet.ip.mcast.maxsocksrc: 128
>>>
>>> Please, what should I do?
>>>
>>> Thank you very much for your time.
>>> -Jan
>>> _______________________________________________
>>> dhcp-users mailing list
>>> dhcp-users at lists.isc.org
>>> https://lists.isc.org/mailman/listinfo/dhcp-users
>>
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>
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