DHCP Server and Dhcp Relay Agent at same server Can't bind to dhcp address: Address already in use

E

Ercan Deger

Hello All,

I am using FreeBSD 11.3 and trying to run dhcpd and dhcrelay at the same device.

Code: 
/usr/local/sbin/dhcpd -cf /usr/local/etc/dhcpd.conf igb3

Listening on BPF/igb3/08:35:71:06:79:d1/192.168.77.0/24
Sending on   BPF/igb3/08:35:71:06:79:d1/192.168.77.0/24

dhcrelay

dhcrelay -i igb1 -4 192.168.75.200

but dhcrelay is giving error

Can't bind to dhcp address: Address already in use

lsof shows me dhcpd running on all interface
Code: 
[root@myserver /]# lsof -n|grep dhc
dhcpd  28213   root  cwd     VDIR               0,81               1024         2 /
dhcpd  28213   root  rtd     VDIR               0,81               1024         2 /
dhcpd  28213   root    3u    unix 0xfffff8005ccac368                0t0           ->0xfffff800058bd6d0
dhcpd  28213   root    4u    VCHR               0,33              0t736        33 /dev/bpf
dhcpd  28213   root    6u    IPv4 0xfffff80131d03860                0t0       UDP *:bootps
I can't run 2 programs at same time

What must I do?

Thanks for your help
 
Hi SirDice,

I have 2 local interfaces,
192.168.75.0/24 network (igb1)
192.168.77.0/24 network (igb3)

I am using dhcpd service at FreeBSD at igb1

for other interface (igb3) I want to use dhcrelay to forward dhcp request to windows machine.

but when I start dhcpd it is listening on all interface so I cant start dhcrelay.

Thanks,
 
I'd either forward everything to the Windows machine or handle all DHCP requests on the FreeBSD host. It's a bit of a management nightmare having to maintain multiple different DHCP servers.
 
Hello!

I have found no way to setup dhcpd for listening only the one interface.

There is a link related to the issue:
But it seems to be a Solaris-specific feature.
I think it is too dificult to use for regular FreeBSD user.

Code: 
Solaris 11
We have integrated a patch from Oracle to use sockets instead of
DLPI on Solaris 11.  This functionality was written for use with
Solaris Studio 12.2 and requires the system/header package.
By default this code is disabled in order to minimize disruptions
for current users.  In order to enable this code you will need to
enable both USE_SOCKETS and USE_V4_PKTINFO as part of the
configuration step.  The command line would be something like:
          ./configure --enable-use-sockets --enable-ipv4-pktinfo
 
Lets circle back to the beginning, why would you want to split up different subnets to different DHCP servers? You know you can host multiple, different, subnets from one DHCP server?
 
I am responsible for igb1 subnet and I have no permission for other network, then I need to forward queries to windows machine. I know it is interesting :)

I think isc dhcpd needs bind to 0.0.0.0 ip so We cant run dhcpd and dhcrelay at same server

I tried im's suggestion;

I used --enable-use-sockets while compiling and dhcpd run on interface ( it needs dhcpd.conf local-address 192.168.77.1;)

I modified Makefile

CONFIGURE_ARGS+=--localstatedir=/var --enable-use-sockets --enable-ipv4-pktinfo


New compiled dhcpd needs seperate configurations and multiple dhcpd process for all required interface.

Listening on Socket/igb3/192.168.77.0/24
Sending on Socket/igb3/192.168.77.0/24
Server starting service.

theoretically It works as expected.

dhcpd 6573 root 6u IPv4 0xfffff80005928e60 0t0 UDP 192.168.77.1:bootps

but no ip leased to pc's

when I changed local-address 0.0.0.0; it works
 
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