ASA DHCP Request incorrect hostname length

Question

I have an ASA 5505 with software version  8.2(1). It is making DHCP  requests for IPSec clients that connect to the ASA. The DHCP requests  packets the ASA makes have an extra '00' appended to the hostname field,  and the length field is the size of the hostname + 1.
The DHCP server  is Microsoft Server 2003 and this causes the hostname to be registered  with an unknown character which appears as []hostname. Then when server  2003 tries to update the DNS record, it fails because of the invalid  character in the hostname.
Is there anyway to have the ASA have the  correct length for the hostname field in the DHCP packet, or a  workaround that will solve this problem?

Answer 1

I am thinking it may not be option 12 in the DHCP packet, but option 81.  I have included a portion of the DHCP request from the ASA below:
   Option: (t=53,l=1) DHCP Message Type = DHCP Request
        Option: (53) DHCP Message Type
        Length: 1
        Value: 03
    Option: (t=57,l=2) Maximum DHCP Message Size = 1152
        Option: (57) Maximum DHCP Message Size
        Length: 2
        Value: 0480
    Option: (t=61,l=42) Client identifier
        Option: (61) Client identifier
        Length: 42
        Value: 00636973636F2D303032312E353537352E636131372D6D79...
    Option: (t=54,l=4) Server Identifier = 192.168.8.3
        Option: (54) Server Identifier
        Length: 4
        Value: C0A80803
    Option: (t=50,l=4) Requested IP Address = 192.168.8.105
        Option: (50) Requested IP Address
        Length: 4
        Value: C0A80869
    Option: (t=12,l=11) Host Name = "myhostname"
        Option: (12) Host Name
        Length: 11
        Value: 6D79686F73746E616D6500
    Option: (t=51,l=4) IP Address Lease Time = 8 days
        Option: (51) IP Address Lease Time
        Length: 4
        Value: 000A8C00
    Option: (t=55,l=6) Parameter Request List
        Option: (55) Parameter Request List
        Length: 6
        Value: 01060F2C0321
        1 = Subnet Mask
        6 = Domain Name Server
        15 = Domain Name
        44 = NetBIOS over TCP/IP Name Server
        3 = Router
        33 = Static Route
    Option: (t=81,l=14) Client Fully Qualified Domain Name
        Option: (81) Client Fully Qualified Domain Name
        Length: 14
        Value: 0400000A6D79686F73746E616D65
        Flags: 0x04
        0000 .... = Reserved flags: 0x00
        .... 0... = Server DDNS: Some server updates
        .... .1.. = Encoding: Binary encoding
        .... ..0. = Server overrides: No override
        .... ...0 = Server: Client
        A-RR result: 0
        PTR-RR result: 0
        Client name: 0A6D79686F73746E616D65
    End Option
    Padding
Notice in option 81 the Client Name has a leading binary value of 0A (which is a new line):  0A6D79686F73746E616D65.
Does CSCsz07757 relate to that?  Is there a way to have the ASA not include option 81 as part of the DHCP requests it makes?
Thank you.