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IMMO WETZEL

dhcrelay duplicated request

Why do I get duplicated request frames towards the dhcp server ?

One as unicast from originator and one as unicast from the relay.

Do I have to do some filtering ?

The dhcp relay is version 4.3.6 self compiled and running inside a docker container.

Routing is enabled between the IU and ID interfaces

Start command dhcrelay -4 -d -iu ens18 -id br_TB102_TMN 10.160.5.2

# route

Kernel IP routing table

Destination Gateway Genmask Flags Metric Ref Use Iface

default gateway 0.0.0.0 UG 0 0 0 ens18

10.160.8.0 0.0.0.0 255.255.254.0 U 0 0 0 ens18

10.160.50.16 0.0.0.0 255.255.255.240 U 0 0 0 br_TB102_TMN

172.17.0.0 0.0.0.0 255.255.0.0 U 0 0 0 docker0

#brctl show

# brctl show

bridge name bridge id STP enabled interfaces

br_TB102_DPU 8000.42b99b1e1cc9 no ens19.2002

ens19.2002.4090

br_TB102_TMN 8000.7a598845a623 no ens20.1002

docker0 8000.0242380e275a no

#ip a

ip a

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000

link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

inet 127.0.0.1/8 scope host lo

valid_lft forever preferred_lft forever

inet6 ::1/128 scope host

valid_lft forever preferred_lft forever

2: ens18: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000

link/ether 36:78:14:96:53:13 brd ff:ff:ff:ff:ff:ff

inet 10.160.8.83/23 brd 10.160.9.255 scope global ens18

valid_lft forever preferred_lft forever

inet6 fe80::3478:14ff:fe96:5313/64 scope link

valid_lft forever preferred_lft forever

3: ens19: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000

link/ether 42:b9:9b:1e:1c:c9 brd ff:ff:ff:ff:ff:ff

inet6 fe80::40b9:9bff:fe1e:1cc9/64 scope link

valid_lft forever preferred_lft forever

4: ens20: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000

link/ether 7a:59:88:45:a6:23 brd ff:ff:ff:ff:ff:ff

inet6 fe80::7859:88ff:fe45:a623/64 scope link

valid_lft forever preferred_lft forever

5: ens20.1002@ens20: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br_TB102_TMN state UP group default qlen 1000

link/ether 7a:59:88:45:a6:23 brd ff:ff:ff:ff:ff:ff

inet6 fe80::7859:88ff:fe45:a623/64 scope link

valid_lft forever preferred_lft forever

6: ens19.2002@ens19: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br_TB102_DPU state UP group default qlen 1000

link/ether 42:b9:9b:1e:1c:c9 brd ff:ff:ff:ff:ff:ff

inet6 fe80::40b9:9bff:fe1e:1cc9/64 scope link

valid_lft forever preferred_lft forever

7: br_TB102_DPU: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000

link/ether 42:b9:9b:1e:1c:c9 brd ff:ff:ff:ff:ff:ff

inet 10.160.60.17/28 brd 10.160.60.31 scope global br_TB102_DPU

valid_lft forever preferred_lft forever

inet6 fe80::40b9:9bff:fe1e:1cc9/64 scope link

valid_lft forever preferred_lft forever

8: br_TB102_TMN: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000

link/ether 7a:59:88:45:a6:23 brd ff:ff:ff:ff:ff:ff

inet 10.160.50.17/28 brd 10.160.50.31 scope global br_TB102_TMN

valid_lft forever preferred_lft forever

inet6 fe80::7859:88ff:fe45:a623/64 scope link

valid_lft forever preferred_lft forever

9: ens19.2002.4090@ens19.2002: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br_TB102_DPU state UP group default qlen 1000

link/ether 42:b9:9b:1e:1c:c9 brd ff:ff:ff:ff:ff:ff

inet6 fe80::40b9:9bff:fe1e:1cc9/64 scope link

valid_lft forever preferred_lft forever

10: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default

link/ether 02:42:38:0e:27:5a brd ff:ff:ff:ff:ff:ff

inet 172.17.0.1/16 scope global docker0

valid_lft forever preferred_lft forever

inet6 fe80::42:38ff:fe0e:275a/64 scope link

valid_lft forever preferred_lft forever

pcap is available at:

https://turl.ca/semr

Mit freundlichen Grüßen / With kind regards

Immo Wetzel

ADTRAN GmbH

Siemensallee 1

17489 Greifswald

Germany

Phone: +49 3834 5352 823

Mobile: +49 151 147 29 225

Skype: immo_wetzel_adtran

[hidden email] PGP-Fingerprint: 7313 7E88 4E19 AACF 45E9 E74D EFF7 0480 F4CF 6426

http://www.adtran.com

Sitz der Gesellschaft: Berlin / Registered office: Berlin

Registergericht: Berlin / Commercial registry: Amtsgericht Charlottenburg, HRB 135656 B

Geschäftsführung / Managing Directors: Roger Shannon, James D. Wilson, Jr., Dr. Eduard Scheiterer

This message has been classified General Business by IMMO WETZEL on Montag, 15. Januar 2018 at 16:19:17.

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IMMO WETZEL

RE: dhcrelay duplicated request

As far as I see the unicast doesn’t have to be touched..

https://tools.ietf.org/html/rfc3046

2.1 Agent Operation

…

Relay agents are NOT required to monitor or modify client-originated

DHCP packets addressed to a server unicast address. This includes

the DHCP-REQUEST sent when entering the RENEWING state.

Immo

This message has been classified General Business by IMMO WETZEL on Montag, 15. Januar 2018 at 16:50:08.

From: IMMO WETZEL
Sent: Monday, January 15, 2018 4:19 PM
To: [hidden email]
Subject: dhcrelay duplicated request

Why do I get duplicated request frames towards the dhcp server ?

One as unicast from originator and one as unicast from the relay.

Do I have to do some filtering ?

The dhcp relay is version 4.3.6 self compiled and running inside a docker container.

Routing is enabled between the IU and ID interfaces

Start command dhcrelay -4 -d -iu ens18 -id br_TB102_TMN 10.160.5.2

# route

Kernel IP routing table

Destination Gateway Genmask Flags Metric Ref Use Iface

default gateway 0.0.0.0 UG 0 0 0 ens18

10.160.8.0 0.0.0.0 255.255.254.0 U 0 0 0 ens18

10.160.50.16 0.0.0.0 255.255.255.240 U 0 0 0 br_TB102_TMN

172.17.0.0 0.0.0.0 255.255.0.0 U 0 0 0 docker0

#brctl show

# brctl show

bridge name bridge id STP enabled interfaces

br_TB102_DPU 8000.42b99b1e1cc9 no ens19.2002

ens19.2002.4090

br_TB102_TMN 8000.7a598845a623 no ens20.1002

docker0 8000.0242380e275a no

#ip a

ip a

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000

link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

inet 127.0.0.1/8 scope host lo

valid_lft forever preferred_lft forever

inet6 ::1/128 scope host

valid_lft forever preferred_lft forever

2: ens18: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000

link/ether 36:78:14:96:53:13 brd ff:ff:ff:ff:ff:ff

inet 10.160.8.83/23 brd 10.160.9.255 scope global ens18

valid_lft forever preferred_lft forever

inet6 fe80::3478:14ff:fe96:5313/64 scope link

valid_lft forever preferred_lft forever

3: ens19: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000

link/ether 42:b9:9b:1e:1c:c9 brd ff:ff:ff:ff:ff:ff

inet6 fe80::40b9:9bff:fe1e:1cc9/64 scope link

valid_lft forever preferred_lft forever

4: ens20: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000

link/ether 7a:59:88:45:a6:23 brd ff:ff:ff:ff:ff:ff

inet6 fe80::7859:88ff:fe45:a623/64 scope link

valid_lft forever preferred_lft forever

5: ens20.1002@ens20: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br_TB102_TMN state UP group default qlen 1000

link/ether 7a:59:88:45:a6:23 brd ff:ff:ff:ff:ff:ff

inet6 fe80::7859:88ff:fe45:a623/64 scope link

valid_lft forever preferred_lft forever

6: ens19.2002@ens19: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br_TB102_DPU state UP group default qlen 1000

link/ether 42:b9:9b:1e:1c:c9 brd ff:ff:ff:ff:ff:ff

inet6 fe80::40b9:9bff:fe1e:1cc9/64 scope link

valid_lft forever preferred_lft forever

7: br_TB102_DPU: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000

link/ether 42:b9:9b:1e:1c:c9 brd ff:ff:ff:ff:ff:ff

inet 10.160.60.17/28 brd 10.160.60.31 scope global br_TB102_DPU

valid_lft forever preferred_lft forever

inet6 fe80::40b9:9bff:fe1e:1cc9/64 scope link

valid_lft forever preferred_lft forever

8: br_TB102_TMN: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000

link/ether 7a:59:88:45:a6:23 brd ff:ff:ff:ff:ff:ff

inet 10.160.50.17/28 brd 10.160.50.31 scope global br_TB102_TMN

valid_lft forever preferred_lft forever

inet6 fe80::7859:88ff:fe45:a623/64 scope link

valid_lft forever preferred_lft forever

9: ens19.2002.4090@ens19.2002: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br_TB102_DPU state UP group default qlen 1000

link/ether 42:b9:9b:1e:1c:c9 brd ff:ff:ff:ff:ff:ff

inet6 fe80::40b9:9bff:fe1e:1cc9/64 scope link

valid_lft forever preferred_lft forever

10: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default

link/ether 02:42:38:0e:27:5a brd ff:ff:ff:ff:ff:ff

inet 172.17.0.1/16 scope global docker0

valid_lft forever preferred_lft forever

inet6 fe80::42:38ff:fe0e:275a/64 scope link

valid_lft forever preferred_lft forever

pcap is available at:

https://turl.ca/semr

Mit freundlichen Grüßen / With kind regards

Immo Wetzel

ADTRAN GmbH

Siemensallee 1

17489 Greifswald

Germany

Phone: +49 3834 5352 823

Mobile: +49 151 147 29 225

Skype: immo_wetzel_adtran

[hidden email] PGP-Fingerprint: 7313 7E88 4E19 AACF 45E9 E74D EFF7 0480 F4CF 6426

http://www.adtran.com

Sitz der Gesellschaft: Berlin / Registered office: Berlin

Registergericht: Berlin / Commercial registry: Amtsgericht Charlottenburg, HRB 135656 B

Geschäftsführung / Managing Directors: Roger Shannon, James D. Wilson, Jr., Dr. Eduard Scheiterer

This message has been classified General Business by IMMO WETZEL on Montag, 15. Januar 2018 at 16:19:17.

_______________________________________________
dhcp-users mailing list
[hidden email]
https://lists.isc.org/mailman/listinfo/dhcp-users

ksladic

Re: dhcrelay duplicated request

In reply to this post by IMMO WETZEL

Hi.

I am not sure about your environment, but I had similar problem on our system.

We have a system with 2 Eth interfaces connected to internal on-board Micrel switch.

I am not sure if this has any similarity with your setup, but here is mine and it may

at least give you some ideas:

1. Unit1: DHCP client in VLAN 100.

2. Unit2: DHCP relay. This unit has 2 Eth Ports on internal switch.

|Unit1 | |Unit2 |

|br0.100| --VLAN100--> |DHCP relay|--to DHCPs->

|DHCPc | | |

The problem was, that the internal switch for the interface on Unit2 was accepting VLAN100 and

also untagged traffic. As soon as I disabled untagged traffic for that port in the switch on Unit2,

I did not get duplicated requests any more.

So, you should look for packets on your interfaces and find out which interfaces kernel is broadcasting

them to. Probably they "leak" to more than one interface you'd like to.

Hope it helps.

RegK

On Tue, Jan 16, 2018 at 4:21 AM, IMMO WETZEL <[hidden email]> wrote:

HI

Why do I get duplicated request frames towards the dhcp server ?

One as unicast from originator and one as unicast from the relay.

Do I have to do some filtering ?

The dhcp relay is version 4.3.6 self compiled and running inside a docker container.

Routing is enabled between the IU and ID interfaces

Start command dhcrelay -4 -d -iu ens18 -id br_TB102_TMN 10.160.5.2

# route

Kernel IP routing table

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface

default         gateway         0.0.0.0         UG    0      0        0 ens18

10.160.8.0      0.0.0.0         255.255.254.0   U     0      0        0 ens18

10.160.50.16    0.0.0.0         255.255.255.240 U     0      0        0 br_TB102_TMN

172.17.0.0      0.0.0.0         255.255.0.0     U     0      0        0 docker0

#brctl show

# brctl show

bridge name      bridge id                             STP enabled      interfaces

br_TB102_DPU                8000.42b99b1e1cc9        no                          ens19.2002

                                                                                                              ens19.2002.4090

br_TB102_TMN                               8000.7a598845a623        no                          ens20.1002

docker0                               8000.0242380e275a        no

#ip a

ip a

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000

    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

    inet 127.0.0.1/8 scope host lo

       valid_lft forever preferred_lft forever

    inet6 ::1/128 scope host

       valid_lft forever preferred_lft forever

2: ens18: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000

    link/ether 36:78:14:96:53:13 brd ff:ff:ff:ff:ff:ff

    inet 10.160.8.83/23 brd 10.160.9.255 scope global ens18

       valid_lft forever preferred_lft forever

    inet6 fe80::3478:14ff:fe96:5313/64 scope link

       valid_lft forever preferred_lft forever

3: ens19: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000

    link/ether 42:b9:9b:1e:1c:c9 brd ff:ff:ff:ff:ff:ff

    inet6 fe80::40b9:9bff:fe1e:1cc9/64 scope link

       valid_lft forever preferred_lft forever

4: ens20: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000

    link/ether 7a:59:88:45:a6:23 brd ff:ff:ff:ff:ff:ff

    inet6 fe80::7859:88ff:fe45:a623/64 scope link

       valid_lft forever preferred_lft forever

5: ens20.1002@ens20: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br_TB102_TMN state UP group default qlen 1000

    link/ether 7a:59:88:45:a6:23 brd ff:ff:ff:ff:ff:ff

    inet6 fe80::7859:88ff:fe45:a623/64 scope link

       valid_lft forever preferred_lft forever

6: ens19.2002@ens19: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br_TB102_DPU state UP group default qlen 1000

    link/ether 42:b9:9b:1e:1c:c9 brd ff:ff:ff:ff:ff:ff

    inet6 fe80::40b9:9bff:fe1e:1cc9/64 scope link

       valid_lft forever preferred_lft forever

7: br_TB102_DPU: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000

    link/ether 42:b9:9b:1e:1c:c9 brd ff:ff:ff:ff:ff:ff

    inet 10.160.60.17/28 brd 10.160.60.31 scope global br_TB102_DPU

       valid_lft forever preferred_lft forever

    inet6 fe80::40b9:9bff:fe1e:1cc9/64 scope link

       valid_lft forever preferred_lft forever

8: br_TB102_TMN: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000

   link/ether 7a:59:88:45:a6:23 brd ff:ff:ff:ff:ff:ff

    inet 10.160.50.17/28 brd 10.160.50.31 scope global br_TB102_TMN

       valid_lft forever preferred_lft forever

    inet6 fe80::7859:88ff:fe45:a623/64 scope link

       valid_lft forever preferred_lft forever

9: ens19.2002.4090@ens19.2002: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br_TB102_DPU state UP group default qlen 1000

    link/ether 42:b9:9b:1e:1c:c9 brd ff:ff:ff:ff:ff:ff

    inet6 fe80::40b9:9bff:fe1e:1cc9/64 scope link

       valid_lft forever preferred_lft forever

10: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default

    link/ether 02:42:38:0e:27:5a brd ff:ff:ff:ff:ff:ff

    inet 172.17.0.1/16 scope global docker0

       valid_lft forever preferred_lft forever

    inet6 fe80::42:38ff:fe0e:275a/64 scope link

       valid_lft forever preferred_lft forever

pcap is available at:

https://turl.ca/semr

Mit freundlichen Grüßen / With kind regards

Immo Wetzel

ADTRAN GmbH

Siemensallee 1

17489 Greifswald

Germany

Phone: <a href="tel:+49%203834%205352823" value="+4938345352823" target="_blank">+49 3834 5352 823

Mobile: <a href="tel:+49%201511%204729225" value="+4915114729225" target="_blank">+49 151 147 29 225

Skype: immo_wetzel_adtran

[hidden email]   PGP-Fingerprint: 7313 7E88 4E19 AACF 45E9 E74D EFF7 0480 F4CF 6426

http://www.adtran.com

Sitz der Gesellschaft: Berlin / Registered office: Berlin

Registergericht: Berlin / Commercial registry: Amtsgericht Charlottenburg, HRB 135656 B

Geschäftsführung / Managing Directors: Roger Shannon, James D. Wilson, Jr., Dr. Eduard Scheiterer

This message has been classified General Business by IMMO WETZEL on Montag, 15. Januar 2018 at 16:19:17.

_______________________________________________
dhcp-users mailing list
[hidden email]
https://lists.isc.org/mailman/listinfo/dhcp-users

_______________________________________________
dhcp-users mailing list
[hidden email]
https://lists.isc.org/mailman/listinfo/dhcp-users