DHCPD ignoring default|max|min-lease-time?
Jason Lixfeld
jason-lists.dhcp at lixfeld.ca
Thu Oct 22 13:49:37 UTC 2015
Hi,
Running dhcpd 4.2.5 on Scientific Linux 6.6 -
I’m seeing some weird behaviour on a few different DHCP clients with regards to offered lease-time, but I’m not certain as to why.
I have three different clients in my lab requesting IPs from this particular shared-network statement. One Mac, one Cisco and one Zhone. As you can see, there are three different options installed for the lease-times:
class "rgw01.lab" {
match if (substring(option agent.remote-id,2,9) = "rgw01.lab");
spawn with option agent.circuit-id;
}
shared-network RGW01_LAB-RESI_INET {
default-lease-time 70000;
min-lease-time 21600;
max-lease-time 43200;
option ip-forwarding off;
option domain-name-servers 66.207.192.6, 206.223.173.7;
subnet 72.15.63.192 netmask 255.255.255.192 {
option dhcp-server-identifier 72.15.63.193;
option routers 72.15.63.193;
pool {
allow members of "rgw01.lab";
range 72.15.63.194 72.15.63.254;
failover peer "failover";
}
}
}
When either of these clients tries to get an IP (the capture below is from the Zhone client), it ignores the default|min|max lease times and offers 1800 seconds instead.
I have no idea where it’s getting 1800 from. The only 1800 value in any config file that I have is the mctl value for the failover config.
Initially, there was no min- or max-lease-time configured. It was only default-lease-time 86400; I added min- and max- and lowered default- to see if the server was somehow sending cached data.
I commented out the entry for this network from the server and restarted the client and server process to flush any data for that network, then added it back in. Still, same results.
After the half-life of the lease, the client sends another request, at which point the server responds with max-lease-time value, so it works the second time around, but not the first time.
Any ideas why the initial offer is 1800 despite the configuration to the contrary?
The capture below was taken directly from the server in question:
08:44:18.285045 IP (tos 0x0, ttl 253, id 54950, offset 0, flags [none], proto UDP (17), length 345)
10.219.45.114.bootps > 10.219.51.249.bootps: [udp sum ok] BOOTP/DHCP, Request from 00:01:47:2d:7a:d0 (oui Unknown), length 317, hops 1, xid 0x5c1749b2, Flags [none] (0x0000)
Gateway-IP 72-15-63-193.beanfield.net
Client-Ethernet-Address 00:01:47:2d:7a:d0 (oui Unknown)
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Discover
Client-ID Option 61, length 7: ether 00:01:47:2d:7a:d0
Parameter-Request Option 55, length 15:
Subnet-Mask, Default-Gateway, Domain-Name-Server, Hostname
Domain-Name, BR, Lease-Time, DHCP-Message
Server-ID, TFTP, NTP, Time-Zone
Option 120, Classless-Static-Route, Vendor-Option
Vendor-Class Option 60, length 22: "ACS_2628A_dslforum.org"
Agent-Information Option 82, length 21:
Circuit-ID SubOption 1, length 6: ^@^D^KM-9^B^A
Remote-ID SubOption 2, length 11: ^A^Irgw01.lab
END Option 255, length 0
08:44:19.285615 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 329)
96-45-195-162.beanfield.net.bootps > 72-15-63-193.beanfield.net.bootps: [bad udp cksum afe2!] BOOTP/DHCP, Reply, length 301, hops 1, xid 0x5c1749b2, Flags [none] (0x0000)
Your-IP 72-15-63-224.beanfield.net
Gateway-IP 72-15-63-193.beanfield.net
Client-Ethernet-Address 00:01:47:2d:7a:d0 (oui Unknown)
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Offer
Server-ID Option 54, length 4: 72-15-63-193.beanfield.net
Lease-Time Option 51, length 4: 1800
Subnet-Mask Option 1, length 4: 255.255.255.192
Default-Gateway Option 3, length 4: 72-15-63-193.beanfield.net
Domain-Name-Server Option 6, length 8: ns3.beanfield.net,ns4.beanfield.net
Agent-Information Option 82, length 21:
Circuit-ID SubOption 1, length 6: ^@^D^KM-9^B^A
Remote-ID SubOption 2, length 11: ^A^Irgw01.lab
END Option 255, length 0
08:44:19.331437 IP (tos 0x0, ttl 253, id 54957, offset 0, flags [none], proto UDP (17), length 357)
10.219.45.114.bootps > 10.219.51.249.bootps: [udp sum ok] BOOTP/DHCP, Request from 00:01:47:2d:7a:d0 (oui Unknown), length 329, hops 1, xid 0x5c1749b2, Flags [none] (0x0000)
Gateway-IP 72-15-63-193.beanfield.net
Client-Ethernet-Address 00:01:47:2d:7a:d0 (oui Unknown)
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Request
Client-ID Option 61, length 7: ether 00:01:47:2d:7a:d0
Requested-IP Option 50, length 4: 72-15-63-224.beanfield.net
Server-ID Option 54, length 4: 72-15-63-193.beanfield.net
Parameter-Request Option 55, length 15:
Subnet-Mask, Default-Gateway, Domain-Name-Server, Hostname
Domain-Name, BR, Lease-Time, DHCP-Message
Server-ID, TFTP, NTP, Time-Zone
Option 120, Classless-Static-Route, Vendor-Option
Vendor-Class Option 60, length 22: "ACS_2628A_dslforum.org"
Agent-Information Option 82, length 21:
Circuit-ID SubOption 1, length 6: ^@^D^KM-9^B^A
Remote-ID SubOption 2, length 11: ^A^Irgw01.lab
END Option 255, length 0
08:44:19.332772 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 329)
96-45-195-162.beanfield.net.bootps > 72-15-63-193.beanfield.net.bootps: [bad udp cksum afdf!] BOOTP/DHCP, Reply, length 301, hops 1, xid 0x5c1749b2, Flags [none] (0x0000)
Your-IP 72-15-63-224.beanfield.net
Gateway-IP 72-15-63-193.beanfield.net
Client-Ethernet-Address 00:01:47:2d:7a:d0 (oui Unknown)
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: ACK
Server-ID Option 54, length 4: 72-15-63-193.beanfield.net
Lease-Time Option 51, length 4: 1800
Subnet-Mask Option 1, length 4: 255.255.255.192
Default-Gateway Option 3, length 4: 72-15-63-193.beanfield.net
Domain-Name-Server Option 6, length 8: ns3.beanfield.net,ns4.beanfield.net
Agent-Information Option 82, length 21:
Circuit-ID SubOption 1, length 6: ^@^D^KM-9^B^A
Remote-ID SubOption 2, length 11: ^A^Irgw01.lab
END Option 255, length 0
08:59:19.577165 IP (tos 0x0, ttl 253, id 55104, offset 0, flags [none], proto UDP (17), length 328)
10.219.45.114.bootps > 10.219.51.249.bootps: [udp sum ok] BOOTP/DHCP, Request from 00:01:47:2d:7a:d0 (oui Unknown), length 300, hops 1, xid 0x5c1749b2, Flags [none] (0x0000)
Client-IP 72-15-63-224.beanfield.net
Gateway-IP 72-15-63-193.beanfield.net
Client-Ethernet-Address 00:01:47:2d:7a:d0 (oui Unknown)
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Request
Client-ID Option 61, length 7: ether 00:01:47:2d:7a:d0
Vendor-Class Option 60, length 22: "ACS_2628A_dslforum.org"
Agent-Information Option 82, length 21:
Circuit-ID SubOption 1, length 6: ^@^D^KM-9^B^A
Remote-ID SubOption 2, length 11: ^A^Irgw01.lab
END Option 255, length 0
08:59:19.578889 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 332)
96-45-195-162.beanfield.net.bootps > 72-15-63-193.beanfield.net.bootps: [bad udp cksum 3c64!] BOOTP/DHCP, Reply, length 304, hops 1, xid 0x5c1749b2, Flags [none] (0x0000)
Client-IP 72-15-63-224.beanfield.net
Your-IP 72-15-63-224.beanfield.net
Gateway-IP 72-15-63-193.beanfield.net
Client-Ethernet-Address 00:01:47:2d:7a:d0 (oui Unknown)
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: ACK
Server-ID Option 54, length 4: 72-15-63-193.beanfield.net
Lease-Time Option 51, length 4: 43200
Subnet-Mask Option 1, length 4: 255.255.255.192
Default-Gateway Option 3, length 4: 72-15-63-193.beanfield.net
Domain-Name-Server Option 6, length 8: ns3.beanfield.net,ns4.beanfield.net
IPF Option 19, length 1: N
Agent-Information Option 82, length 21:
Circuit-ID SubOption 1, length 6: ^@^D^KM-9^B^A
Remote-ID SubOption 2, length 11: ^A^Irgw01.lab
END Option 255, length 0
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