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<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">Hi,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">My DHCP server software is dhcpd v4.4.2 and running on CentOS 7. The DHCP Server IP address is 10.2.1.10.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">In the example, the client MAC is 74:a7:11:22:33:44 and its IP is 10.1.14.94.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">After I added the client MAC to the subclass "mytest" in the dhcpd.conf and restarted the dhcpd,
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">I expected the client's next DHCP renew request would not succeed because of
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">the following statement:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">deny members of "mytest" in the pool (range 10.1.1.1 10.1.16.255) definition.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">But it did not happen. The client did renewing its address 10.1.14.94 after the server restarts.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">By comparison, I added a few other clients to the subclass "mytest" in the dhcpd.conf file and restarted the dhcp servers. Those clients did not renew their existing IP in the range 10.1.1.1
10.1.16.255, instead, got their new IP addresses from the other pool range 10.50.252.1 10.50.255.254. These clients' behavior is expected.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">Is this a DHCP sever software bug or something else?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">Thanks for your time.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">Related lines in the dhcpd.conf:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">shared-network net580 {<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> option domain-name "test.domain.name";<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> option domain-name-servers 10.3.1.2,10.3.1.3,10.3.1.4;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> subnet 10.1.0.0 netmask 255.255.0.0 {<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> option routers 10.1.0.1;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> }<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> pool {<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> failover peer "dhcpnet";<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> deny dynamic bootp clients;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> range 10.1.1.1 10.1.16.255;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> deny members of "mytest";<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> default-lease-time 3600;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> max-lease-time 3600;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> }<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> pool {<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> failover peer "dhcpnet";<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> deny dynamic bootp clients;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> range 10.50.252.1 10.50.255.254;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> allow members of "mytest";<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> default-lease-time 300;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> max-lease-time 300;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> option domain-name-servers 10.2.1.10, 10.2.1.2;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> }<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">}<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">subclass "mytest" 1:74:A7:11:22:33:44;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">Tcpdump DHCP Packets:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">13:25:11.943051 IP (tos 0x0, ttl 62, id 23969, offset 0, flags [none], proto UDP (17), length 354)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> 10.1.0.3.bootps > 10.2.1.10.bootps: [udp sum ok] BOOTP/DHCP, Request from 74:a7:11:22:33:44, length 326, xid 0xffc1ae1b, secs 65535, Flags [none] (0x0000)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Gateway-IP 10.1.0.3<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Client-Ethernet-Address 74:a7:11:22:33:44<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Vendor-rfc1048 Extensions<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Magic Cookie 0x65835363<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> DHCP-Message Option 53, length 1: Request<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Requested-IP Option 50, length 4: 10.1.14.94<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Server-ID Option 54, length 4: 10.2.1.10<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> MSZ Option 57, length 2: 1500<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Vendor-Class Option 60, length 12: "dhcpcd-5.5.6"<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Hostname Option 12, length 16: "amazon-72fdddaaa"<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Parameter-Request Option 55, length 10:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Subnet-Mask, Static-Route, Default-Gateway, Domain-Name-Server<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Domain-Name, MTU, BR, Lease-Time<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> RN, RB<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Agent-Information Option 82, length 20:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Circuit-ID SubOption 1, length 18: IRB-irb.2043:ae3.0<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> END Option 255, length 0<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">13:25:11.943058 IP (tos 0x0, ttl 62, id 39591, offset 0, flags [none], proto UDP (17), length 355)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> 10.1.0.2.bootps > 10.2.1.10.bootps: [udp sum ok] BOOTP/DHCP, Request from 74:a7:11:22:33:44, length 327, xid 0xffc1ae1b, secs 65535, Flags [none] (0x0000)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Gateway-IP 10.1.0.2<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Client-Ethernet-Address 74:a7:11:22:33:44<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Vendor-rfc1048 Extensions<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Magic Cookie 0x65835363<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> DHCP-Message Option 53, length 1: Request<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Requested-IP Option 50, length 4: 10.1.14.94<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Server-ID Option 54, length 4: 10.2.1.10<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> MSZ Option 57, length 2: 1500<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Vendor-Class Option 60, length 12: "dhcpcd-5.5.6"<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Hostname Option 12, length 16: "amazon-72fdddaaa"<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Parameter-Request Option 55, length 10:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Subnet-Mask, Static-Route, Default-Gateway, Domain-Name-Server<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Domain-Name, MTU, BR, Lease-Time<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> RN, RB<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Agent-Information Option 82, length 21:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Circuit-ID SubOption 1, length 19: IRB-irb.2000:ae00.0<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> END Option 255, length 0<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">13:25:11.943779 IP (tos 0x0, ttl 64, id 37878, offset 0, flags [DF], proto UDP (17), length 365)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> 10.2.1.10.bootps > 10.1.0.3.bootps: [bad udp cksum 0xc984 -> 0xdcb7!] BOOTP/DHCP, Reply, length 337, xid 0xffc1ae1b, secs 65535, Flags [none] (0x0000)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Your-IP 10.1.14.94<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Gateway-IP 10.1.0.3<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Client-Ethernet-Address 74:a7:11:22:33:44<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Vendor-rfc1048 Extensions<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Magic Cookie 0x65835363<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> DHCP-Message Option 53, length 1: ACK<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Server-ID Option 54, length 4: 10.2.1.10<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Lease-Time Option 51, length 4: 3600<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Subnet-Mask Option 1, length 4: 255.255.0.0<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Default-Gateway Option 3, length 4: 10.1.0.1<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Domain-Name-Server Option 6, length 12: 10.3.1.2,10.3.1.3,10.3.1.4<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Domain-Name Option 15, length 31: "test.domain.name"<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Agent-Information Option 82, length 20:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Circuit-ID SubOption 1, length 18: IRB-irb.2043:ae3.0<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> END Option 255, length 0<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">13:25:11.944080 IP (tos 0x0, ttl 64, id 44173, offset 0, flags [DF], proto UDP (17), length 366)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> 10.2.1.10.bootps > 10.1.0.2.bootps: [bad udp cksum 0xc984 -> 0xa7b5!] BOOTP/DHCP, Reply, length 338, xid 0xffc1ae1b, secs 65535, Flags [none] (0x0000)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Your-IP 10.1.14.94<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Gateway-IP 10.1.0.2<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Client-Ethernet-Address 74:a7:11:22:33:44<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Vendor-rfc1048 Extensions<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Magic Cookie 0x65835363<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> DHCP-Message Option 53, length 1: ACK<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Server-ID Option 54, length 4: 10.2.1.10<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Lease-Time Option 51, length 4: 3600<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Subnet-Mask Option 1, length 4: 255.255.0.0<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Default-Gateway Option 3, length 4: 10.1.0.1<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Domain-Name-Server Option 6, length 12: 10.3.1.2,10.3.1.3,10.3.1.4<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Domain-Name Option 15, length 31: "test.domain.name"<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Agent-Information Option 82, length 21:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> Circuit-ID SubOption 1, length 19: IRB-irb.2000:ae00.0<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> END Option 255, length 0<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"> <o:p>
</o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">Jim Yang<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif">Cornell IT<o:p></o:p></span></p>
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