Access Point and DHCP from router

[Frotihngdog.ca]

At our towers we have routers that hand out Public IP's to each client via DHCP.

When a PS2 is set to AP mode and a client is registered to the AP that client is unable to pull a public IP from our router.

We have 2 work arounds:
1. Staticly set the public IP, netmask, gatewat and DNS at the client
2. Set the AP up as a AP-WDS.

Is ther a way to have DHCP from our Router work in AP mode?

[UBNT-Mike.Ford]

Hello Frotihngdog.ca,

Can you provide us more information about the type and configuration of the router you are using for DHCP?

Thanks,

Mike

[Frotihngdog.ca]

It's FreeBSD on Soekris 45xx, 48xx or 55xx.

Port 0 is used as the WAN side
Ports 1, 2 are used on the AP side to hand out public IP's to our clients.

All the radio's are staticly assigned private IP address.

For example:

sis0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
lladdr 00:00:24:c6:fd:60
groups: egress
media: Ethernet autoselect (100baseTX full-duplex)
status: active
inet 10.1.7.2 netmask 0xffffff00 broadcast 10.1.7.255
inet 64.201.74.102 netmask 0xfffffffc broadcast 64.201.74.103
sis1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
lladdr 00:00:24:c6:fd:61
media: Ethernet autoselect (100baseTX full-duplex)
status: active
inet 10.1.16.1 netmask 0xffffff00 broadcast 10.1.16.255
inet 64.201.90.97 netmask 0xffffffe0 broadcast 64.201.90.127
sis2: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
lladdr 00:00:24:c6:fd:62
media: Ethernet autoselect (none)
status: no carrier
inet 192.168.3.2 netmask 0xffffff00 broadcast 192.168.3.255

In this case SIS2 is not in use. All our Towers are routed out.
We've used Moto Canopy with this same configuration with no problems.

[MaximumISP]

I have the same issue with a ptp link
NS5 used as Ap PS5 as client
DHCP addresses will not pass through this link and it absolutely refuses to work in wds modes at all

Dog what firmware are you using I am now on 3.1.1

[UBNT-Mike.Ford]

Hey Guys,

I am actively investigating this here in the lab on multiple setups. So far I have been unable to reproduce a DHCP issue.

Thank you,

Mike

[Frotihngdog.ca]

I am running 3.1.1 as well.

We tryed it again today, but still no luck. The only way we could get it to work was to either staticly assign the client their public IP or put the AP into AP-WDS and the client into STATION-WDS and then it would accept the dhcp address.

Mike are you DHCPing with private address's or public?

[Frotihngdog.ca]

Here's the cfg for the AP if it helps:

users.status=enabled
radio.1.thresh62g=17
radio.1.thresh62b=17
radio.1.thresh62a=17
wireless.1.l2_isolation=disabled
netconf.2.allmulti=disabled
radio.1.dfs.status=
wireless.1.addmtikie=enabled
wireless.1.sper=disabled
tshaper.status=disabled
wireless.1.signal_led4=65
wireless.1.signal_led3=73
wireless.1.signal_led2=80
wireless.1.signal_led1=94
radio.1.ext_antenna=disabled
wireless.1.compression=enabled
wireless.1.frameburst=enabled
wireless.1.fastframes=enabled
radio.1.frag=off
radio.1.rts=off
wireless.1.wmmlevel=0
wireless.1.wmm=enabled
ebtables.3.cmd=-t broute -A BROUTING --protocol 0x888e --in-interface ath0 -j DROP
ebtables.3.status=disabled
ebtables.2.cmd=-t nat -A POSTROUTING --out-interface ath0 -j arpnat --arpnat-target ACCEPT
ebtables.2.status=disabled
ebtables.1.cmd=-t nat -A PREROUTING --in-interface ath0 -j arpnat --arpnat-target ACCEPT
ebtables.1.status=disabled
ebtables.status=enabled
route.1.netmask=0
route.1.ip=0.0.0.0
route.1.gateway=10.1.13.1
route.1.devname=br0
route.1.status=enabled
route.status=enabled
dhcpc.1.devname=br0
dhcpc.1.status=disabled
dhcpc.status=disabled
dhcpd.1.status=disabled
dhcpd.status=disabled
netconf.3.up=enabled
netconf.3.netmask=255.255.255.0
netconf.3.ip=10.1.13.11
netconf.3.devname=br0
netconf.3.status=enabled
netconf.2.up=enabled
netconf.2.netmask=255.255.255.0
netconf.2.ip=0.0.0.0
netconf.2.devname=ath0
netconf.2.status=enabled
netconf.1.promisc=enabled
netconf.1.up=enabled
netconf.1.netmask=255.255.255.0
netconf.1.ip=0.0.0.0
netconf.1.devname=eth0
netconf.1.status=enabled
netconf.status=enabled
bridge.1.port.2.devname=ath0
bridge.1.port.1.devname=eth0
bridge.1.fd=1
bridge.1.devname=br0
bridge.status=enabled
wireless.1.hide_ssid=enabled
wireless.1.ssid=AP1
wireless.1.security=none
wireless.1.devname=ath0
wireless.1.status=enabled
wireless.status=enabled
radio.1.tx_antenna=2
radio.1.rx_antenna=2
radio.1.tx_antenna_diversity=disabled
radio.1.rx_antenna_diversity=disabled
radio.1.ack.auto=disabled
radio.1.acktimeout=65
radio.1.txpower=16
radio.1.ieee_mode=g
radio.1.rate.auto=enabled
radio.1.rate.max=27M
radio.1.mode=master
radio.1.devname=ath0
radio.1.status=enabled
radio.ratemodule=ath_rate_onoe
radio.countrycode=124
radio.status=enabled
httpd.port=80
httpd.status=enabled
users.1.password=Hh25NiJWBsEfc
users.1.name=root
users.1.status=enabled
wireless.1.wds=enabled
radio.1.channel=1
wireless.1.macclone=disabled
radio.1.countrycode=124
radio.1.mcastrate=3M
radio.1.clksel=1
radio.1.chanshift=0
wireless.1.authmode=1
wireless.1.ap=
wireless.1.autowds=disabled
wireless.1.wds.1.peer=00:15:6D:A6:54:A6
wireless.1.wds.2.peer=
wireless.1.wds.3.peer=
wireless.1.wds.4.peer=
wireless.1.wds.5.peer=
wireless.1.wds.6.peer=
wireless.1.mac_acl.status=disabled
wireless.1.mac_acl.policy=allow
wireless.1.mac_acl.1.status=disabled
wireless.1.mac_acl.1.mac=
wireless.1.mac_acl.2.status=disabled
wireless.1.mac_acl.2.mac=
wireless.1.mac_acl.3.status=disabled
wireless.1.mac_acl.3.mac=
wireless.1.mac_acl.4.status=disabled
wireless.1.mac_acl.4.mac=
wireless.1.mac_acl.5.status=disabled
wireless.1.mac_acl.5.mac=
wireless.1.mac_acl.6.status=disabled
wireless.1.mac_acl.6.mac=
wireless.1.mac_acl.7.status=disabled
wireless.1.mac_acl.7.mac=
wireless.1.mac_acl.8.status=disabled
wireless.1.mac_acl.8.mac=
wireless.1.mac_acl.9.status=disabled
wireless.1.mac_acl.9.mac=
wireless.1.mac_acl.10.status=disabled
wireless.1.mac_acl.10.mac=
wireless.1.mac_acl.11.status=disabled
wireless.1.mac_acl.11.mac=
wireless.1.mac_acl.12.status=disabled
wireless.1.mac_acl.12.mac=
wireless.1.mac_acl.13.status=disabled
wireless.1.mac_acl.13.mac=
wireless.1.mac_acl.14.status=disabled
wireless.1.mac_acl.14.mac=
wireless.1.mac_acl.15.status=disabled
wireless.1.mac_acl.15.mac=
wireless.1.mac_acl.16.status=disabled
wireless.1.mac_acl.16.mac=
aaa.status=disabled
aaa.1.status=disabled
wpasupplicant.status=disabled
wpasupplicant.device.1.status=disabled
ppp.1.password=
ppp.status=disabled
iptables.3.status=disabled
ppp.1.status=disabled
iptables.status=disabled
resolv.nameserver.1.ip=216.185.64.10
resolv.nameserver.1.status=enabled
resolv.nameserver.2.status=enabled
resolv.status=enabled
ebtables.50.status=disabled
ebtables.51.status=disabled
netmode=bridge
igmpproxy.status=disabled
bridge.1.stp.status=disabled
resolv.nameserver.2.ip=216.185.64.6
snmp.status=enabled
snmp.community=ops
snmp.contact=NEST
snmp.location=datp
resolv.host.1.status=enabled
resolv.host.1.name=AP1

[UBNT-Zy]

Hello Frotihngdog,

I've tried your AP-WDS to STA-WDS setup (Half rates, hidden SSID) with the cfg file you had provided.
Laptop connected to STA-WDS ethernet port had obtained DHCP settings successfully from the DHCP server on the AP-WDS ethernet port.
So far we can not reproduce the issue you had encountered. Is there a possibility to capture the wireless packets at your site for further investigation?

Thank you for the effort.
Z.

[UBNT-Zy]

One more thought for the case if the station uses b-only mode while AP is set to b/g mixed mode:
Can you please check if setting the "Multicast Rate" to value 1 Mbps in Advanced page of the AP solves the DHCP issue?

Thank you,
Z.

[Frotihngdog.ca]

I MIGHT be able to capture the packets of one of the links but it's gonna take some time. We've had alot of Thunderstorms lately so things are alittle nuts right now.

I'll also try setting the MULTI-CAST data to 1Mbps at the same time, but again it's gonn abe a while before I can get back to testing it. I'll try to keep you posted.

[Frotihngdog.ca]

Well I did some testing here at home. However I only had 1 PS2 in the truck so I couldn't make a PS2 to PS2 link. So I did a PS2 to Wireless Card test useing one of Soekris Routers. The test was successful. I managed to pull a public IP from the SIS1 interface on the router.

Next step is to test with 2 PS2's. But that will probably have to wait until next week.

TEST 1
--------
IBM-T23 with Lucent Technologies 802.11b WaveLan Card-7.43.0.9 > PS2 -- SOEKRIS NET4511

NET4511 CFG:
sis0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
lladdr 00:00:24:c3:a3:50
groups: egress
media: Ethernet autoselect (none)
status: no carrier
inet 192.168.1.2 netmask 0xffffff00 broadcast 192.168.1.255
sis1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
lladdr 00:00:24:c3:a3:51
media: Ethernet autoselect (100baseTX full-duplex)
status: active
inet 88.xxx.xxx.xxx netmask 0xfffffff8 broadcast 88.xxx.xxx.xxx
inet 10.1.10.1 netmask 0xffffff00 broadcast 10.1.10.255

PS2 cfg:
users.status=enabled
resolv.nameserver.2.ip=216.185.64.6
ebtables.3.cmd=-t broute -A BROUTING --protocol 0x888e --in-interface ath0 -j DROP
ebtables.3.status=disabled
ebtables.2.cmd=-t nat -A POSTROUTING --out-interface ath0 -j arpnat --arpnat-target ACCEPT
ebtables.2.status=disabled
ebtables.1.cmd=-t nat -A PREROUTING --in-interface ath0 -j arpnat --arpnat-target ACCEPT
ebtables.1.status=disabled
ebtables.status=enabled route.1.netmask=0 route.1.ip=0.0.0.0 route.1.gateway=10.1.10.1
route.1.devname=br0
route.1.status=enabled
route.status=enabled
dhcpc.1.devname=br0
dhcpc.1.status=disabled
dhcpc.status=disabled
dhcpd.1.status=disabled
dhcpd.status=disabled
netconf.3.up=enabled
netconf.3.netmask=255.255.255.0
netconf.3.ip=10.1.10.11
netconf.3.devname=br0
netconf.3.status=enabled
netconf.2.up=enabled
netconf.2.netmask=255.255.255.0
netconf.2.ip=0.0.0.0
netconf.2.devname=ath0
netconf.2.status=enabled
netconf.1.promisc=enabled
netconf.1.up=enabled
netconf.1.netmask=255.255.255.0
netconf.1.ip=0.0.0.0
netconf.1.devname=eth0
netconf.1.status=enabled
netconf.status=enabled
bridge.1.port.2.devname=ath0
bridge.1.port.1.devname=eth0
bridge.1.fd=1
bridge.1.devname=br0
bridge.status=enabled
wireless.1.hide_ssid=disabled
wireless.1.ssid=UBNT
wireless.1.security=none
wireless.1.devname=ath0
wireless.1.status=enabled
wireless.status=enabled
radio.1.tx_antenna=1
radio.1.rx_antenna=1
radio.1.tx_antenna_diversity=disabled
radio.1.rx_antenna_diversity=disabled
radio.1.ack.auto=enabled
radio.1.acktimeout=44
radio.1.txpower=1
radio.1.ieee_mode=b
radio.1.rate.auto=enabled
radio.1.rate.max=11M
radio.1.mode=master
radio.1.devname=ath0
radio.1.status=enabled
radio.ratemodule=ath_rate_onoe
radio.countrycode=124
radio.status=enabled
httpd.port=80
httpd.status=enabled
users.1.password=VvpvCwhccFv6Q
users.1.name=ubnt
users.1.status=enabled
wireless.1.wds=disabled
radio.1.channel=1
wireless.1.macclone=disabled
radio.1.countrycode=124
radio.1.mcastrate=1M
radio.1.clksel=0
radio.1.chanshift=0
wireless.1.authmode=1
wireless.1.ap=
wireless.1.mac_acl.status=disabled
wireless.1.mac_acl.policy=allow
wireless.1.mac_acl.1.status=disabled
wireless.1.mac_acl.1.mac=
wireless.1.mac_acl.2.status=disabled
wireless.1.mac_acl.2.mac=
wireless.1.mac_acl.3.status=disabled
wireless.1.mac_acl.3.mac=
wireless.1.mac_acl.4.status=disabled
wireless.1.mac_acl.4.mac=
wireless.1.mac_acl.5.status=disabled
wireless.1.mac_acl.5.mac=
wireless.1.mac_acl.6.status=disabled
wireless.1.mac_acl.6.mac=
wireless.1.mac_acl.7.status=disabled
wireless.1.mac_acl.7.mac=
wireless.1.mac_acl.8.status=disabled
wireless.1.mac_acl.8.mac=
wireless.1.mac_acl.9.status=disabled
wireless.1.mac_acl.9.mac=
wireless.1.mac_acl.10.status=disabled
wireless.1.mac_acl.10.mac=
wireless.1.mac_acl.11.status=disabled
wireless.1.mac_acl.11.mac=
wireless.1.mac_acl.12.status=disabled
wireless.1.mac_acl.12.mac=
wireless.1.mac_acl.13.status=disabled
wireless.1.mac_acl.13.mac=
wireless.1.mac_acl.14.status=disabled
wireless.1.mac_acl.14.mac=
wireless.1.mac_acl.15.status=disabled
wireless.1.mac_acl.15.mac=
wireless.1.mac_acl.16.status=disabled
wireless.1.mac_acl.16.mac=
aaa.status=disabled
aaa.1.status=disabled
wpasupplicant.status=disabled
wpasupplicant.device.1.status=disabled
ppp.1.password=
ppp.status=disabled
iptables.3.status=disabled
ppp.1.status=disabled
iptables.status=disabled
resolv.nameserver.1.ip=216.185.64.10
resolv.nameserver.1.status=enabled
resolv.nameserver.2.status=enabled
resolv.status=enabled
ebtables.50.status=disabled
ebtables.51.status=disabled
netmode=bridge
igmpproxy.status=disabled
bridge.1.stp.status=disabled
wireless.1.wmm=enabled
wireless.1.wmmlevel=0
radio.1.rts=off
radio.1.frag=off
wireless.1.fastframes=enabled
wireless.1.frameburst=enabled
wireless.1.compression=enabled
radio.1.ext_antenna=disabled
wireless.1.signal_led1=94
wireless.1.signal_led2=80
wireless.1.signal_led3=73
wireless.1.signal_led4=65
tshaper.status=disabled
wireless.1.sper=disabled
wireless.1.addmtikie=disabled
radio.1.dfs.status=
netconf.2.allmulti=disabled
wireless.1.l2_isolation=disabled
radio.1.thresh62a=28
radio.1.thresh62b=28
radio.1.thresh62g=28
snmp.status=enabled
snmp.community=reztelops
snmp.contact=test
snmp.location=test

[Frotihngdog.ca]

OK...I did some more testing (finally) Short and sweet of it is that I was still unable to get DHCP to work while in Access Point Mode. I tried changeing the MULTI-CAST setting, QoS and removeing the DNS address's, still nothing.

So I took a packet capture of the DHCP process...so here it is, I'm not sure how to read it.

1.000176 10.1.38.11 10.1.38.19 ICMP Echo (ping) reply

4.354597 Ubiquiti_a6:54:a6 CDP/VTP/DTP/PAgP/UDLD CDP Device ID: UBNT

5.001564 Ubiquiti_a6:54:a6 D-Link_50:91:d5 ARP Who has 10.1.38.19? Tell 10.1.38.11

5.001596 D-Link_50:91:d5 Ubiquiti_a6:54:a6 ARP 10.1.38.19 is at 00:1b:11:50:91:d5

24.098602 0.0.0.0 255.255.255.255 DHCP DHCP Discover - Transaction ID 0x2b24c78f

26.348302 Ubiquiti_a6:57:b1 CDP/VTP/DTP/PAgP/UDLD CDP Device ID: UBNT

29.098232 0.0.0.0 255.255.255.255 DHCP DHCP Discover - Transaction ID 0x2b24c78f

29.103952 Olicom_c3:a3:51 Broadcast ARP Who has 66.207.118.130? Tell 66.207.118.129

38.101207 0.0.0.0 255.255.255.255 DHCP DHCP Discover - Transaction ID 0x2b24c78f

54.104185 0.0.0.0 255.255.255.255 DHCP DHCP Discover - Transaction ID 0x2b24c78f

64.352182 Ubiquiti_a6:54:a6 CDP/VTP/DTP/PAgP/UDLD CDP Device ID: UBNT

86.345978 Ubiquiti_a6:57:b1 CDP/VTP/DTP/PAgP/UDLD CDP Device ID: UBNT

87.115649 D-Link_50:91:d5 Broadcast ARP Gratuitous ARP for 169.254.47.197 (Request)

I also tried setting the DHCP on the router to use a private address scheme...still no good.

[Frotihngdog.ca]

Hey,

Here are the tcpdump outputs from each radio...hope it helps:

AP SIDE:
-------------
XS2.ar2316.v3.2-rc2.3578.080807.1722# ./tcpdump -i br0 -s 0 -n -e -v port 68
tcpdump: listening on br0, link-type EN10MB (Ethernet), capture size 65535 bytes
17:39:05.988937 00:15:6d:a6:57:b1 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x0, ttl 128, id 0, offset 0, flags [none], proto: UDP (17), length: 328) 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 00:08:74:22:31:ec, length: 300, xid:0x196f802, flags: [Broadcast]
Client Ethernet Address: 00:08:74:22:31:ec
Vendor-rfc1048:
DHCP:DISCOVER
NOAUTO:Y
CID:[ether]00:08:74:22:31:ec
HN:"hometeam"
VC:"MSFT 5.0"
PR:SM+DN+DG+NS+WNS+WNT+WSC+RD+SR+T249+VO
17:39:06.016737 00:00:24:c3:a3:51 > 00:15:6d:a6:57:b1, ethertype IPv4 (0x0800), length 342: (tos 0x10, ttl 16, id 0, offset 0, flags [none], proto: UDP (17), length: 328) 10.1.38.1.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length: 300, xid:0x196f802, flags: [Broadcast]
Your IP: 10.1.38.50
Server IP: 10.1.38.1
Client Ethernet Address: 00:08:74:22:31:ec
Vendor-rfc1048:
DHCP:OFFER
SID:10.1.38.1
LT:120
SM:255.255.255.0
DN:"reztel.net"
DG:10.1.38.1
NS:216.185.64.10,216.185.64.6
17:39:09.987488 00:15:6d:a6:57:b1 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x0, ttl 128, id 1, offset 0, flags [none], proto: UDP (17), length: 328) 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 00:08:74:22:31:ec, length: 300, xid:0x196f802, secs:1024, flags: [Broadcast]
Client Ethernet Address: 00:08:74:22:31:ec
Vendor-rfc1048:
DHCP:DISCOVER
NOAUTO:Y
CID:[ether]00:08:74:22:31:ec
HN:"hometeam"
VC:"MSFT 5.0"
PR:SM+DN+DG+NS+WNS+WNT+WSC+RD+SR+T249+VO
17:39:09.992925 00:00:24:c3:a3:51 > 00:15:6d:a6:57:b1, ethertype IPv4 (0x0800), length 342: (tos 0x10, ttl 16, id 0, offset 0, flags [none], proto: UDP (17), length: 328) 10.1.38.1.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length: 300, xid:0x196f802, secs:1024, flags: [Broadcast]
Your IP: 10.1.38.50
Server IP: 10.1.38.1
Client Ethernet Address: 00:08:74:22:31:ec
Vendor-rfc1048:
DHCP:OFFER
SID:10.1.38.1
LT:120
SM:255.255.255.0
DN:"reztel.net"
DG:10.1.38.1
NS:216.185.64.10,216.185.64.6
17:39:17.989197 00:15:6d:a6:57:b1 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x0, ttl 128, id 2, offset 0, flags [none], proto: UDP (17), length: 328) 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 00:08:74:22:31:ec, length: 300, xid:0x196f802, secs:3072, flags: [Broadcast]
Client Ethernet Address: 00:08:74:22:31:ec
Vendor-rfc1048:
DHCP:DISCOVER
NOAUTO:Y
CID:[ether]00:08:74:22:31:ec
HN:"hometeam"
VC:"MSFT 5.0"
PR:SM+DN+DG+NS+WNS+WNT+WSC+RD+SR+T249+VO
17:39:17.994178 00:00:24:c3:a3:51 > 00:15:6d:a6:57:b1, ethertype IPv4 (0x0800), length 342: (tos 0x10, ttl 16, id 0, offset 0, flags [none], proto: UDP (17), length: 328) 10.1.38.1.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length: 300, xid:0x196f802, secs:3072, flags: [Broadcast]
Your IP: 10.1.38.50
Server IP: 10.1.38.1
Client Ethernet Address: 00:08:74:22:31:ec
Vendor-rfc1048:
DHCP:OFFER
SID:10.1.38.1
LT:120
SM:255.255.255.0
DN:"reztel.net"
DG:10.1.38.1
NS:216.185.64.10,216.185.64.6
17:39:32.991171 00:15:6d:a6:57:b1 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x0, ttl 128, id 3, offset 0, flags [none], proto: UDP (17), length: 328) 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 00:08:74:22:31:ec, length: 300, xid:0x196f802, secs:6912, flags: [Broadcast]
Client Ethernet Address: 00:08:74:22:31:ec
Vendor-rfc1048:
DHCP:DISCOVER
NOAUTO:Y
CID:[ether]00:08:74:22:31:ec
HN:"hometeam"
VC:"MSFT 5.0"
PR:SM+DN+DG+NS+WNS+WNT+WSC+RD+SR+T249+VO
17:39:32.995996 00:00:24:c3:a3:51 > 00:15:6d:a6:57:b1, ethertype IPv4 (0x0800), length 342: (tos 0x10, ttl 16, id 0, offset 0, flags [none], proto: UDP (17), length: 328) 10.1.38.1.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length: 300, xid:0x196f802, secs:6912, flags: [Broadcast]
Your IP: 10.1.38.50
Server IP: 10.1.38.1
Client Ethernet Address: 00:08:74:22:31:ec
Vendor-rfc1048:
DHCP:OFFER
SID:10.1.38.1
LT:120
SM:255.255.255.0
DN:"reztel.net"
DG:10.1.38.1
NS:216.185.64.10,216.185.64.6
==============================================

STATION SIDE:
------------------
XS2.ar2316.v3.2-rc2.3578.080807.1722# ./tcpdump -i br0 -s 0 -n -e -v port 68
tcpdump: listening on br0, link-type EN10MB (Ethernet), capture size 65535 bytes
17:39:26.188904 00:15:6d:a6:57:b1 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x0, ttl 128, id 72, offset 0, flags [none], proto: UDP (17), length: 328) 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 00:08:74:22:31:ec, length: 300, xid:0x4ea99285, flags: [Broadcast]
Client Ethernet Address: 00:08:74:22:31:ec
Vendor-rfc1048:
DHCP:DISCOVER
NOAUTO:Y
CID:[ether]00:08:74:22:31:ec
RQ:169.254.56.245
HN:"hometeam"
VC:"MSFT 5.0"
PR:SM+DN+DG+NS+WNS+WNT+WSC+RD+SR+T249+VO
17:39:26.198788 00:00:24:c3:a3:51 > 00:15:6d:a6:57:b1, ethertype IPv4 (0x0800), length 342: (tos 0x10, ttl 16, id 0, offset 0, flags [none], proto: UDP (17), length: 328) 10.1.38.1.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length: 300, xid:0x4ea99285, flags: [Broadcast]
Your IP: 10.1.38.50
Server IP: 10.1.38.1
Client Ethernet Address: 00:08:74:22:31:ec
Vendor-rfc1048:
DHCP:OFFER
SID:10.1.38.1
LT:120
SM:255.255.255.0
DN:"reztel.net"
DG:10.1.38.1
NS:216.185.64.10,216.185.64.6
17:39:29.189259 00:15:6d:a6:57:b1 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x0, ttl 128, id 73, offset 0, flags [none], proto: UDP (17), length: 328) 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 00:08:74:22:31:ec, length: 300, xid:0x4ea99285, secs:768, flags: [Broadcast]
Client Ethernet Address: 00:08:74:22:31:ec
Vendor-rfc1048:
DHCP:DISCOVER
NOAUTO:Y
CID:[ether]00:08:74:22:31:ec
RQ:169.254.56.245
HN:"hometeam"
VC:"MSFT 5.0"
PR:SM+DN+DG+NS+WNS+WNT+WSC+RD+SR+T249+VO
17:39:29.196787 00:00:24:c3:a3:51 > 00:15:6d:a6:57:b1, ethertype IPv4 (0x0800), length 342: (tos 0x10, ttl 16, id 0, offset 0, flags [none], proto: UDP (17), length: 328) 10.1.38.1.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length: 300, xid:0x4ea99285, secs:768, flags: [Broadcast]
Your IP: 10.1.38.50
Server IP: 10.1.38.1
Client Ethernet Address: 00:08:74:22:31:ec
Vendor-rfc1048:
DHCP:OFFER
SID:10.1.38.1
LT:120
SM:255.255.255.0
DN:"reztel.net"
DG:10.1.38.1
NS:216.185.64.10,216.185.64.6
17:39:37.190948 00:15:6d:a6:57:b1 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x0, ttl 128, id 74, offset 0, flags [none], proto: UDP (17), length: 328) 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 00:08:74:22:31:ec, length: 300, xid:0x4ea99285, secs:2816, flags: [Broadcast]
Client Ethernet Address: 00:08:74:22:31:ec
Vendor-rfc1048:
DHCP:DISCOVER
NOAUTO:Y
CID:[ether]00:08:74:22:31:ec
RQ:169.254.56.245
HN:"hometeam"
VC:"MSFT 5.0"
PR:SM+DN+DG+NS+WNS+WNT+WSC+RD+SR+T249+VO
17:39:37.197350 00:00:24:c3:a3:51 > 00:15:6d:a6:57:b1, ethertype IPv4 (0x0800), length 342: (tos 0x10, ttl 16, id 0, offset 0, flags [none], proto: UDP (17), length: 328) 10.1.38.1.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length: 300, xid:0x4ea99285, secs:2816, flags: [Broadcast]
Your IP: 10.1.38.50
Server IP: 10.1.38.1
Client Ethernet Address: 00:08:74:22:31:ec
Vendor-rfc1048:
DHCP:OFFER
SID:10.1.38.1
LT:120
SM:255.255.255.0
DN:"reztel.net"
DG:10.1.38.1
NS:216.185.64.10,216.185.64.6
17:39:52.192929 00:15:6d:a6:57:b1 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x0, ttl 128, id 75, offset 0, flags [none], proto: UDP (17), length: 328) 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 00:08:74:22:31:ec, length: 300, xid:0x4ea99285, secs:6656, flags: [Broadcast]
Client Ethernet Address: 00:08:74:22:31:ec
Vendor-rfc1048:
DHCP:DISCOVER
NOAUTO:Y
CID:[ether]00:08:74:22:31:ec
RQ:169.254.56.245
HN:"hometeam"
VC:"MSFT 5.0"
PR:SM+DN+DG+NS+WNS+WNT+WSC+RD+SR+T249+VO
17:39:52.199288 00:00:24:c3:a3:51 > 00:15:6d:a6:57:b1, ethertype IPv4 (0x0800), length 342: (tos 0x10, ttl 16, id 0, offset 0, flags [none], proto: UDP (17), length: 328) 10.1.38.1.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length: 300, xid:0x4ea99285, secs:6656, flags: [Broadcast]
Your IP: 10.1.38.50
Server IP: 10.1.38.1
Client Ethernet Address: 00:08:74:22:31:ec
Vendor-rfc1048:
DHCP:OFFER
SID:10.1.38.1
LT:120
SM:255.255.255.0
DN:"reztel.net"
DG:10.1.38.1
NS:216.185.64.10,216.185.64.6

[UBNT-keba]

Hi all

It seems I found what is wrong. According to your tcpdump info DHCP server sends offer by unicast packets:

17:39:06.016737 00:00:24:c3:a3:51 > 00:15:6d:a6:57:b1, ethertype IPv4 (0x0800),
length 342: (tos 0x10, ttl 16, id 0, offset 0, flags [none], proto: UDP (17),
length: 328) 10.1.38.1.67 > 255.255.255.255.68: BOOTP/DHCP,
Reply, length: 300, xid:0x196f802, flags: [Broadcast]

That is totally wrong and does not match RFC 2131 which says:

A client that cannot receive unicast IP datagrams until its protocol
software has been configured with an IP address SHOULD set the
BROADCAST bit in the 'flags' field to 1 in any DHCPDISCOVER or
DHCPREQUEST messages that client sends. The BROADCAST bit will
provide a hint to the DHCP server and BOOTP relay agent to broadcast
any messages to the client on the client's subnet.

Because request was with Broadcast flag set:

17:39:05.988937 00:15:6d:a6:57:b1 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x0, ttl 128, id 0, offset 0, flags [none], proto: UDP (17), length: 328) 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 00:08:74:22:31:ec, length: 300, xid:0x196f802, flags: [Broadcast]

and the response has Broadcast flag set as well by DHCP server it self, so why DHCP server sends it as Unicast packet to NS2 Station?

We were testing there with:
Internet Systems Consortium DHCP Server v3.0.5 on linux box
Dnsmasq v2.35 as DHCP server on UBNT units (LS/NS/PS)
Mikrotik DHCP server with RouterOS v3.11, v2.9.51
all works good according RFC.

[Frotihngdog.ca]

If I plug the PS2 that is configured as a AP into out router and then put a Wireless network card into my laptop the DHCP works just fine.

The problem is only appearing when I add the STATION PS2 into the mix.

That would lead me to believe that our DHCP server is fine and the AP is fine but there is something going on with the association of the STATION to the AP that isn't passing the DHCP request properly.

[Frotihngdog.ca]

Also, i did another packet capture between our Router/DHCP Server and my laptop (wired).

Frame 2 (342 bytes on wire, 342 bytes captured)
Arrival Time: Aug 12, 2008 08:41:37.977803000
Time delta from previous captured frame: 0.000424000 seconds
Time delta from previous displayed frame: 0.000424000 seconds
Time since reference or first frame: 12.190506000 seconds
Frame Number: 19
Frame Length: 110 bytes
Capture Length: 110 bytes
Frame is marked: False
Protocols in frame: eth:ip:udp:nbns[/b]

[Frotihngdog.ca]

Well looks like we may have found the problem to the DHCP problem (thanks to Keba) Turns out the version of DHCPD we are running is old and not ISC Standard.

So in short make sure your servers are up to date :)

Thanks again Keba.

Cheers

[Frotihngdog.ca]

Recently after upgradeing our AP's to 3.3.1 we noticed that DHCP stared working properly. Just thought everone would like to know