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Today's Topics:
1. dhcpd not seeing HCPDISCOVER traffic (dhcp-quest...@kraitch.net)
2. Re: Question about Option 252 for Web Proxy Auto-Discovery
(Bill Shirley)
3. Re: Question about Option 252 for Web Proxy Auto-Discovery
(Glenn Satchell)
----------------------------------------------------------------------
Message: 1
Date: Thu, 09 Sep 2021 15:07:18 -0700
From: dhcp-quest...@kraitch.net
To: dhcp-users@lists.isc.org
Subject: dhcpd not seeing HCPDISCOVER traffic
Message-ID: <613a8596.hP1CSJZ1ezQiTP5/%dhcp-quest...@kraitch.net>
Content-Type: text/plain; charset=us-ascii
Hello.
We have a stable working single VRF
*virtual routing and Forwarding) network technology
with routers perfuming dhcp relaying for
multiple networks to ISC 4.4.2-P1 DHCP
revers running on RHEL (Red Hat Enterprise Linux) 7 servers.
We are migrating to a multiple VRF environment.
We were surprised when we encountered an issue
with our first test network on a new VRF with
the router dhcp relaying to a dhcp server on the
original VRF did not work. The dhcp server does
not appear to see and does not log or process the
DHCPDISCOVER traffic being relayed form the new
VRF. When we run tcpdump on the dhcp server,
tcpdump does see the DHCPDISCOVER traffic being
relayed form the new VRF. We also noticed that
tcpdump showed the DHCPDISCOVER traffic has a
"bad udp cksum."
Could the bad checksum be why the dhcp server is
not logging or processing the DHCPDISCOVER requests?
We tried compiling dhcpd with DEBUG_CHECKSUM_VERBOSE
defined in in includes/site.h but that did not
appears to provide any helpful insight. BTW, we
could not compile with DEBUG_CHECKSUM defined.
"ethtool -k" on a RHEL dhcp server showed that offload of
checksums was enabled. Disabling offloading
did not change tcpdump shewing bad udp checksums and
did not result in dhcpd seeing and processing the
DHCPDISCOVERs with bad udp checksums.
Assuming the bad udp checksums are why dhcpod is
not processing the DHCPDISCOVERs, what can be done from
the dhcpd end? There does not be a #define to
ignore bad udp checksums. We are not sure what
the code in common//packet.c does but it might be a
candidate for modification if ignoring the bad udp checksums
is possible,
Our main question remains are the bad udp checksums on
the DHCPDISCOVERs preventing the fault dhcpd from
providing dhco support?
Thanks,
mark
------------------------------
Message: 2
Date: Fri, 10 Sep 2021 02:57:59 -0400
From: Bill Shirley <b...@c3po.polymerindustries.biz>
To: dhcp-users@lists.isc.org
Subject: Re: Question about Option 252 for Web Proxy Auto-Discovery
Message-ID:
<a9de3a92-20e4-fbd6-d731-ff9e731d2...@c3po.polymerindustries.biz>
Content-Type: text/plain; charset="utf-8"; Format="flowed"
# local proxy autodiscovery
option local-pac-server??????????? code 252 = text;
subnet 192.168.1.0 netmask 255.255.255.0 {
? option local-pac-server "http://www.example.com/wpad.dat";;
.
}
Bill
On 9/8/2021 12:30 PM, perl-list wrote:
> I have no specific knowledge of option 252, but, generally speaking in the
> dhcp config file when defining a string value, it is usually in quotes. I
> would guess that to be the case with this as well.
>
> ----- Original Message -----
>> From: "Parkin, Richard (R.)" <rpark...@ford.com>
>> To: "Users of ISC DHCP" <dhcp-users@lists.isc.org>
>> Sent: Wednesday, September 8, 2021 10:09:04 AM
>> Subject: Question about Option 252 for Web Proxy Auto-Discovery
>> Greetings!
>> I have a question about configuring Option 252 for Web Proxy Auto-Discovery.
>> Our IPAM allowed me to generate a configuration statement that resembles
>> this:
>> option 252 http://example.com/wpad.dat;
>> What I am wondering is if the URL string needs to be quoted for this to work,
>> like so:
>> option 252 ?http://example.com/wpad.dat?;
>> I haven?t been able to find a definitive answer. Is it safer to assume the
>> quotes are needed?
>> Thanks!
>> --
>> Rich Parkin
>> Ford Motor Company
>> DDI Planner (DNS, DHCP, IPAM)
>> _______________________________________________
>> ISC funds the development of this software with paid support subscriptions.
>> Contact us at https://www.isc.org/contact/ for more information.
>> dhcp-users mailing list
>> dhcp-users@lists.isc.org
>> https://lists.isc.org/mailman/listinfo/dhcp-users
>>
>> _______________________________________________
>> ISC funds the development of this software with paid support subscriptions.
>> Contact us at https://www.isc.org/contact/ for more information.
>>
>> dhcp-users mailing list
>> dhcp-users@lists.isc.org
>> https://lists.isc.org/mailman/listinfo/dhcp-users
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------------------------------
Message: 3
Date: Fri, 10 Sep 2021 19:20:41 +1000
From: Glenn Satchell <glenn.satch...@uniq.com.au>
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: Re: Question about Option 252 for Web Proxy Auto-Discovery
Message-ID: <c87b19a2b51a1e465cb86004cb77f...@uniq.com.au>
Content-Type: text/plain; charset=US-ASCII; format=flowed
Hi Richard,
The definitive answer is in the dhcp-options man page:
REFERENCE: OPTION STATEMENTS
The text data type specifies an NVT ASCII string, which must be
enclosed in double quotes - for example, to specify a root-path option,
the syntax would be
option root-path "10.0.1.4:/var/tmp/rootfs";
and further down that same document
TEXT
option new-name code new-code = text ;
An option whose type is text will encode an ASCII text string.
For example:
option sql-default-connection-name code 194 = text;
option sql-default-connection-name "PRODZA";
regards,
Glenn
On 2021-09-10 16:57, Bill Shirley wrote:
> # local proxy autodiscovery
> option local-pac-server code 252 = text;
>
> subnet 192.168.1.0 netmask 255.255.255.0 {
> option local-pac-server "http://www.example.com/wpad.dat";;
> .
> }
>
> Bill
>
> On 9/8/2021 12:30 PM, perl-list wrote:
>
> I have no specific knowledge of option 252, but, generally speaking in
> the dhcp config file when defining a string value, it is usually in
> quotes. I would guess that to be the case with this as well.
>
> ----- Original Message -----
>
> From: "Parkin, Richard (R.)" <rpark...@ford.com>
> To: "Users of ISC DHCP" <dhcp-users@lists.isc.org>
> Sent: Wednesday, September 8, 2021 10:09:04 AM
> Subject: Question about Option 252 for Web Proxy Auto-Discovery
>
> Greetings!
>
> I have a question about configuring Option 252 for Web Proxy
> Auto-Discovery.
>
> Our IPAM allowed me to generate a configuration statement that
> resembles this:
>
> option 252 http://example.com/wpad.dat;
>
> What I am wondering is if the URL string needs to be quoted for this to
> work,
> like so:
>
> option 252 "http://example.com/wpad.dat";;
>
> I haven't been able to find a definitive answer. Is it safer to assume
> the
> quotes are needed?
>
> Thanks!
>
> --
>
> Rich Parkin
>
> Ford Motor Company
>
> DDI Planner (DNS, DHCP, IPAM)
>
> _______________________________________________
> ISC funds the development of this software with paid support
> subscriptions.
> Contact us at https://www.isc.org/contact/ for more information.
>
> dhcp-users mailing list
> dhcp-users@lists.isc.org
> https://lists.isc.org/mailman/listinfo/dhcp-users
>
> _______________________________________________
> ISC funds the development of this software with paid support
> subscriptions. Contact us at https://www.isc.org/contact/ for more
> information.
>
> dhcp-users mailing list
> dhcp-users@lists.isc.org
> https://lists.isc.org/mailman/listinfo/dhcp-users
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------------------------------
End of dhcp-users Digest, Vol 155, Issue 5
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