<div dir="ltr"><div>I tried this in my lab, and option 54 is supposed to be set to the DHCP server IP which assigned the IP. </div><div>Regardless, it can not be the global broadcast address as far as I know.</div><div><br></div>According to RFC2132:<div><pre class="gmail-newpage" style="font-size:13.3333px;margin-top:0px;margin-bottom:0px;color:rgb(0,0,0)"><span class="gmail-h3" style="line-height:0pt;display:inline;font-size:1em;font-weight:bold"><h3 style="line-height:0pt;display:inline;font-size:1em"><a class="gmail-selflink" name="section-9.7" href="https://tools.ietf.org/html/rfc2132#section-9.7" style="color:black;text-decoration-line:none">9.7</a>. Server Identifier</h3></span>
This option is used in DHCPOFFER and DHCPREQUEST messages, and may
optionally be included in the DHCPACK and DHCPNAK messages. DHCP
servers include this option in the DHCPOFFER in order to allow the
client to distinguish between lease offers. DHCP clients use the
contents of the 'server identifier' field as the destination address
for any DHCP messages unicast to the DHCP server. DHCP clients also
indicate which of several lease offers is being accepted by including
this option in a DHCPREQUEST message.
The identifier is the IP address of the selected server.
The code for this option is 54, and its length is 4.</pre><pre class="gmail-newpage" style="font-size:13.3333px;margin-top:0px;margin-bottom:0px;color:rgb(0,0,0)"><br></pre><div><br></div>Hope this helps,<br><br>Jason</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, May 9, 2017 at 10:42 AM, S. M. Hossein Hamidi <span dir="ltr"><<a href="mailto:hossein.hamidi@gmail.com" target="_blank">hossein.hamidi@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hi,<div><br></div><div>I have a kea installation with a relay agent ahead. Normal DHCP operations except DHCP Release works well. When, I send a DHCP Release message I encounter following error message:</div><div><br></div><div>"DHCP4_PACKET_DROP_0003 [hwtype=1 00:00:00:11:11:11], cid=[no info], tid=0x3602fcf, from interface ens39: it contains a foreign server identifier"<br></div><div><br></div><div>Below is the packet content I captured using Wireshark. By the way, the server IP Address is 192.168.234.100 and Relay Agent IP address is 192.168.0.5</div><div><br></div><div>------------------------------<wbr>-</div><div><div>Frame 522: 294 bytes on wire (2352 bits), 294 bytes captured (2352 bits) on interface 0</div><div>Linux cooked capture</div><div>Internet Protocol Version 4, Src: 192.168.234.1, Dst: 192.168.234.100</div><div>User Datagram Protocol, Src Port: 67 (67), Dst Port: 67 (67)</div><div>Bootstrap Protocol (Release)</div><div> Message type: Boot Request (1)</div><div> Hardware type: Ethernet (0x01)</div><div> Hardware address length: 6</div><div> Hops: 1</div><div> Transaction ID: 0x03602fcf</div><div> Seconds elapsed: 0</div><div> Bootp flags: 0x0000 (Unicast)</div><div> Client IP address: 255.255.255.255</div><div> Your (client) IP address: 0.0.0.0</div><div> Next server IP address: 192.168.234.100</div><div> Relay agent IP address: 192.168.0.5</div><div> Client MAC address: 00:00:00_11:11:11 (00:00:00:11:11:11)</div><div> Client hardware address padding: 00000000000000000000</div><div> Server host name not given</div><div> Boot file name not given</div><div> Magic cookie: DHCP</div><div> Option: (53) DHCP Message Type (Release)</div><div> Length: 1</div><div> DHCP: Release (7)</div><div> Option: (54) DHCP Server Identifier</div><div> Length: 4</div><div> DHCP Server Identifier: 255.255.255.255</div><div> Option: (255) End</div><div> Option End: 255</div></div><div>------------------------------<wbr>----</div><div><br></div><div>Any idea what could be the cause of this problem?</div><div><br></div><div>Regards,</div></div>
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