dhcrelay does not work

[ali reza zareian]

hello

dhcrelay does not work with this scenario

       A                                   B
 ---------------                          -----------------
          -----------
| dhcp server      |               | dhcrelay          |
 |client     |
| FreeBSD 11.0  |<--------->| FreeBSD 11.0 |<-------------->|windows|
 -------------------- em7         em0-------------- em1
 -----------

 ----------------------- DHCP server configuration ---
    /usr/local/sbin/dhcpd -user dhcpd -group dhcpd -chroot /var/dhcpd -cf
/etc/dhcpd.conf -pf      /var/run/dhcpd.pid em7

    dnsmasq is enable

dhcpd.conf:
option domain-name "localdomain";
option ldap-server code 95 = text;
option domain-search-list code 119 = text;
option arch code 93 = unsigned integer 16; # RFC4578

default-lease-time 7200;
max-lease-time 86400;
log-facility local7;
one-lease-per-client true;
deny duplicates;
ping-check true;
update-conflict-detection false;
authoritative;
subnet 100.100.10.0 netmask 255.255.255.0 {
  pool {
    range 100.100.10.1 100.100.10.50;
  }

  option routers 100.100.10.10;
  option domain-name-servers 100.100.10.10;

}
--------------------------------------------------------
on device B:
dhcrelay  -i em0 -i em1 100.100.10.10
em1:192.168.1.10/24
em0:100.100.10.100
--------------------------------------------------------
when i test this scenario DHCP packets arrive to DHCP server but they can
not return to device B where my dhcrelay is running.
if i connect device C to DHCP server directly ,It takes ip fast so i think
my DHCP server config is working fine

What caused the problem?
What's wrong here??