dhcpcd-discuss

Hi Roy,

I tried dhcpd with "ddns-update_style interim" but it makes no difference.  The encoding of the fqdn returned by dhcpd seems to depend on the fqdn.encoding setting and the default value is ASCII.  My dhcpd is not new enough to support "ddns-updat-style standard" so I could not make that test right now (4.3 and newer is needed).

It would be good if dhcpcd could support checking the E flag and accepting ASCII if E is 0 since ISC dhcpd seems to be a DHCP server that is in common use.  I don't know if all administrators configure it to use RFC 1035 encoded fqdn.  I also don't know how the DHCP servers in Windows Server 2008 and Windows Server 2012 behave.

Paul

-----Original Message-----
From: Walrath, Paul 
Sent: Thursday, July 02, 2015 10:16 AM
To: Roy Marples; dhcpcd-discuss@xxxxxxxxxxxx
Subject: RE: [dhcpcd-discuss] RE: DHCP Option 81 Client FQDN and new_fqdn

Hi Roy,

Here's what I have for a dhcpd configuration for DHCPv4:

ddns-update-style none;
default-lease-time 600;
max-lease-time 7200;
log-facility local7;

subnet 192.168.2.0 netmask 255.255.255.0 {
    option subnet-mask 255.255.255.0;
    option broadcast-address 192.168.2.255;
    option routers 192.168.2.1;
    option netbios-name-servers 192.168.2.1;

    option domain-name "example.org";
    option domain-name-servers 8.8.8.8, 8.8.4.4;

    range 192.168.2.100 192.168.2.199;
    default-lease-time 43200;
    max-lease-time	86400;
}

host testbed1 {
    # Replace this with your device's MAC address
    hardware ethernet 11:22:33:44:55:66;
    fixed-address 192.168.2.149;
    option host-name "testbed1";
    option fqdn.fqdn "t1.fqdn.walrath.name";
    option fqdn.encoded true;
}

I will try to use "ddns-update-style standard;" instead of "ddns-update-style none;" to see if it makes a difference.  Note that I am not doing DDNS so I'm not sure how dhcpd will take this.

Paul

-----Original Message-----
From: Roy Marples [mailto:roy@xxxxxxxxxxxx] 
Sent: Thursday, July 02, 2015 9:44 AM
To: Walrath, Paul; dhcpcd-discuss@xxxxxxxxxxxx
Subject: Re: [dhcpcd-discuss] RE: DHCP Option 81 Client FQDN and new_fqdn

Hi Paul

On 02/07/2015 17:40, Walrath, Paul wrote:
> I did a test and found that ISC dhcpd 4.2.4 DHCP server did not look
> at the E bit in Option 81 that is sent from the client.  Dhcpcd sent
> Option 81 with the E bit set but dhcpd returned Option 81 with the
> fqdn still ASCII encoded.  I had to configure dhcpd using "option
> fqdn.encoding true" in order to get it to return the fqdn using RFC
> 1035 encoding.  It appears as though ASCII is its default encoding,
> at least for the fqdn response that it returns to the client.  RFC
> 4702 says that a server MUST use the same encoding as that used by
> the client, so I don't understand this result.  It appears as though
> ISC dhcpd is not in compliance with RFC 4702.

Could you share the fqdn part of your config? I can never get dhcpd to
send back any FQDN option.

But from the sounds of it, you are right that it does appear to be a bug
in dhcpd.

There are other areas where dhcpd/dhclient isn't entirely RFC compliant
so it doesn't come as any big surprise either.

Roy