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  • dhcp-snooping option 82 drops valid dhcp requests on 2610 series Procurve switches

    - by kce
    We are slowly starting to implement dhcp-snooping on our HP ProCurve 2610 series switches, all running the R.11.72 firmware. I'm seeing some strange behavior where dhcp-request or dhcp-renew packets are dropped when originating from "downstream" switches due "untrusted relay information from client". The full error: Received untrusted relay information from client <mac-address> on port <port-number> In more detail we have a 48 port HP2610 (Switch A) and a 24 port HP2610 (Switch B). Switch B is "downstream" of Switch A by virtue of a DSL connection to one of Switch A ports. The dhcp server is connected to Switch A. The relevant bits are as follows: Switch A dhcp-snooping dhcp-snooping authorized-server 192.168.0.254 dhcp-snooping vlan 1 168 interface 25 name "Server" dhcp-snooping trust exit Switch B dhcp-snooping dhcp-snooping authorized-server 192.168.0.254 dhcp-snooping vlan 1 interface Trk1 dhcp-snooping trust exit The switches are set to trust BOTH the port the authorized dhcp server is attached to and its IP address. This is all well and good for the clients attached to Switch A, but the clients attached to Switch B get denied due to the "untrusted relay information" error. This is odd for a few reasons 1) dhcp-relay is not configured on either switch, 2) the Layer-3 network here is flat, same subnet. DHCP packets should not have a modified option 82 attribute. dhcp-relay does appear to be enabled by default however: SWITCH A# show dhcp-relay DHCP Relay Agent : Enabled Option 82 : Disabled Response validation : Disabled Option 82 handle policy : append Remote ID : mac Client Requests Server Responses Valid Dropped Valid Dropped ---------- ---------- ---------- ---------- 0 0 0 0 SWITCH B# show dhcp-relay DHCP Relay Agent : Enabled Option 82 : Disabled Response validation : Disabled Option 82 handle policy : append Remote ID : mac Client Requests Server Responses Valid Dropped Valid Dropped ---------- ---------- ---------- ---------- 40156 0 0 0 And interestingly enough the dhcp-relay agent seems very busy on Switch B, but why? As far as I can tell there is no reason why dhcp requests need a relay with this topology. And furthermore I can't tell why the upstream switch is dropping legitimate dhcp requests for untrusted relay information when the relay agent in question (on Switch B) isn't modifying the option 82 attributes anyway. Adding the no dhcp-snooping option 82 on Switch A allows the dhcp traffic from Switch B to be approved by Switch A, by virtue of just turning off that feature. What are the repercussions of not validating option 82 modified dhcp traffic? If I disable option 82 on all my "upstream" switches - will they pass dhcp traffic from any downstream switch regardless of that traffic's legitimacy? This behavior is client operating system agnostic. I see it with both Windows and Linux clients. Our DHCP servers are either Windows Server 2003 or Windows Server 2008 R2 machines. I see this behavior regardless of the DHCP servers' operating system. Can anyone shed some light on what's happening here and give me some recommendations on how I should proceed with configuring the option 82 setting? I feel like i just haven't completely grokked dhcp-relaying and option 82 attributes.

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  • nokia cell phone not accepting IP from dnsmasq dhcp server

    - by samix
    Hello, I having problem connecting a NOkia cell phone to my home wifi network. The wifi network is provided by a wireless card in a machine running Debian Testing and 2.6.26-2-686 kernel. The cars is D-Link DWL-G520 working in ap mode and has WPA encryption enabled. The wireless network is provided by hostapd using madwifi driver. Windows and Mac machines work properly with this wifi network. When I try to get the Nokia phone to connect to the wifi network, I get these lines in my dnsmasq log (to see lines without wrapping, here is the pastebin link for convenience - http://pastebin.com/m466c8fd2): Oct 27 13:25:21 red hostapd: ath0: STA 11:22:33:44:55:66 IEEE 802.11: disassociated Oct 27 13:25:21 red hostapd: ath0: STA 11:22:33:44:55:66 IEEE 802.11: associated Oct 27 13:25:21 red hostapd: ath0: STA 11:22:33:44:55:66 RADIUS: starting accounting session 4AE664FA-00000036 Oct 27 13:25:21 red hostapd: ath0: STA 11:22:33:44:55:66 WPA: pairwise key handshake completed (WPA) Oct 27 13:25:21 red hostapd: ath0: STA 11:22:33:44:55:66 WPA: group key handshake completed (WPA) Oct 27 13:25:21 red dnsmasq-dhcp[11451]: 3875439214 Available DHCP range: 192.168.5.150 -- 192.168.5.199 Oct 27 13:25:21 red dnsmasq-dhcp[11451]: 3875439214 DHCPDISCOVER(ath0) 0.0.0.0 11:22:33:44:55:66 Oct 27 13:25:21 red dnsmasq-dhcp[11451]: 3875439214 DHCPOFFER(ath0) 192.168.5.21 11:22:33:44:55:66 Oct 27 13:25:21 red dnsmasq-dhcp[11451]: 3875439214 requested options: 12:hostname, 6:dns-server, 15:domain-name, Oct 27 13:25:21 red dnsmasq-dhcp[11451]: 3875439214 requested options: 1:netmask, 3:router, 28:broadcast, 120:sip-server Oct 27 13:25:21 red dnsmasq-dhcp[11451]: 3875439214 tags: known, ath0 Oct 27 13:25:21 red dnsmasq-dhcp[11451]: 3875439214 next server: 192.168.5.1 Oct 27 13:25:21 red dnsmasq-dhcp[11451]: 3875439214 sent size: 1 option: 53:message-type 02 Oct 27 13:25:21 red dnsmasq-dhcp[11451]: 3875439214 sent size: 4 option: 54:server-identifier 192.168.5.1 Oct 27 13:25:21 red dnsmasq-dhcp[11451]: 3875439214 sent size: 4 option: 51:lease-time 00:00:46:50 Oct 27 13:25:21 red dnsmasq-dhcp[11451]: 3875439214 sent size: 4 option: 58:T1 00:00:23:28 Oct 27 13:25:21 red dnsmasq-dhcp[11451]: 3875439214 sent size: 4 option: 59:T2 00:00:3d:86 Oct 27 13:25:21 red dnsmasq-dhcp[11451]: 3875439214 sent size: 4 option: 1:netmask 255.255.255.0 Oct 27 13:25:21 red dnsmasq-dhcp[11451]: 3875439214 sent size: 4 option: 28:broadcast 192.168.5.255 Oct 27 13:25:21 red dnsmasq-dhcp[11451]: 3875439214 sent size: 4 option: 3:router 192.168.5.1 Oct 27 13:25:21 red dnsmasq-dhcp[11451]: 3875439214 sent size: 4 option: 6:dns-server 192.168.5.1 Oct 27 13:25:21 red dnsmasq-dhcp[11451]: 3875439214 sent size: 8 option: 15:domain-name home.pvt Oct 27 13:25:21 red dnsmasq-dhcp[11451]: 3875439214 sent size: 3 option: 12:hostname NokiaCellPhone Anybody know the problem might be? If I switch off dnsmasq dhcp queries logging, i.e. if I decrease the verbosity of the log, all I see are two lines of DHCPDISCOVER(ath0) and DHCPOFFER(ath0) repeatedly in the log with no acceptance by the cell phone. It appears as though the phone is not accepting the dhcp offer. However, if I give the phone a static IP address in its configuration, it works properly on the wifi network. So it appears as though the problem is dhcp related. Hints? Suggestions? Installed stuff: $ dpkg -l dnsmasq hostap* | grep ^i ii dnsmasq 2.50-1 A small caching DNS proxy and DHCP/TFTP server ii dnsmasq-base 2.50-1 A small caching DNS proxy and DHCP/TFTP server ii hostapd 1:0.6.9-3 user space IEEE 802.11 AP and IEEE 802.1X/WPA/ Thanks. PS: Here is the DHCP tcp dump for more information (with mac addresses changed): $ sudo dhcpdump -i ath0 -h ^11:22:33:44:55:66 TIME: 2009-10-30 12:15:32.916 IP: 0.0.0.0 (1:22:33:44:55:66) 255.255.255.255 (ff:ff:ff:ff:ff:ff) OP: 1 (BOOTPREQUEST) HTYPE: 1 (Ethernet) HLEN: 6 HOPS: 0 XID: c3f93d53 SECS: 0 FLAGS: 7f80 CIADDR: 0.0.0.0 YIADDR: 0.0.0.0 SIADDR: 0.0.0.0 GIADDR: 0.0.0.0 CHADDR: 11:22:33:44:55:66:00:00:00:00:00:00:00:00:00:00 SNAME: . FNAME: . OPTION: 53 ( 1) DHCP message type 1 (DHCPDISCOVER) OPTION: 50 ( 4) Request IP address 0.0.0.0 OPTION: 61 ( 7) Client-identifier 01:11:22:33:44:55:66 OPTION: 55 ( 7) Parameter Request List 12 (Host name) 6 (DNS server) 15 (Domainname) 1 (Subnet mask) 3 (Routers) 28 (Broadcast address) 120 (SIP Servers DHCP Option) OPTION: 57 ( 2) Maximum DHCP message size 576 TIME: 2009-10-30 12:15:32.918 IP: 0.0.0.0 (1:22:33:44:55:66) 255.255.255.255 (ff:ff:ff:ff:ff:ff) OP: 1 (BOOTPREQUEST) HTYPE: 1 (Ethernet) HLEN: 6 HOPS: 0 XID: c3f93d53 SECS: 0 FLAGS: 7f80 CIADDR: 0.0.0.0 YIADDR: 0.0.0.0 SIADDR: 0.0.0.0 GIADDR: 0.0.0.0 CHADDR: 11:22:33:44:55:66:00:00:00:00:00:00:00:00:00:00 SNAME: . FNAME: . OPTION: 53 ( 1) DHCP message type 1 (DHCPDISCOVER) OPTION: 50 ( 4) Request IP address 0.0.0.0 OPTION: 61 ( 7) Client-identifier 01:11:22:33:44:55:66 OPTION: 55 ( 7) Parameter Request List 12 (Host name) 6 (DNS server) 15 (Domainname) 1 (Subnet mask) 3 (Routers) 28 (Broadcast address) 120 (SIP Servers DHCP Option) OPTION: 57 ( 2) Maximum DHCP message size 576 TIME: 2009-10-30 12:15:32.918 IP: 192.168.5.1 (a:bb:cc:dd:ee:ff) 255.255.255.255 (ff:ff:ff:ff:ff:ff) OP: 2 (BOOTPREPLY) HTYPE: 1 (Ethernet) HLEN: 6 HOPS: 0 XID: c3f93d53 SECS: 0 FLAGS: 7f80 CIADDR: 0.0.0.0 YIADDR: 192.168.5.21 SIADDR: 192.168.5.1 GIADDR: 0.0.0.0 CHADDR: 11:22:33:44:55:66:00:00:00:00:00:00:00:00:00:00 SNAME: . FNAME: . OPTION: 53 ( 1) DHCP message type 2 (DHCPOFFER) OPTION: 54 ( 4) Server identifier 192.168.5.1 OPTION: 51 ( 4) IP address leasetime 18000 (5h) OPTION: 58 ( 4) T1 9000 (2h30m) OPTION: 59 ( 4) T2 15750 (4h22m30s) OPTION: 1 ( 4) Subnet mask 255.255.255.0 OPTION: 28 ( 4) Broadcast address 192.168.5.255 OPTION: 3 ( 4) Routers 192.168.5.1 OPTION: 6 ( 4) DNS server 192.168.5.1 OPTION: 15 ( 8) Domainname home.pvt OPTION: 12 ( 3) Host name Nokia_E63 TIME: 2009-10-30 12:15:34.922 IP: 0.0.0.0 (1:22:33:44:55:66) 255.255.255.255 (ff:ff:ff:ff:ff:ff) OP: 1 (BOOTPREQUEST) HTYPE: 1 (Ethernet) HLEN: 6 HOPS: 0 XID: c3f93d53 SECS: 2 FLAGS: 7f80 CIADDR: 0.0.0.0 YIADDR: 0.0.0.0 SIADDR: 0.0.0.0 GIADDR: 0.0.0.0 CHADDR: 11:22:33:44:55:66:00:00:00:00:00:00:00:00:00:00 SNAME: . FNAME: . OPTION: 53 ( 1) DHCP message type 1 (DHCPDISCOVER) OPTION: 50 ( 4) Request IP address 0.0.0.0 OPTION: 61 ( 7) Client-identifier 01:11:22:33:44:55:66 OPTION: 55 ( 7) Parameter Request List 12 (Host name) 6 (DNS server) 15 (Domainname) 1 (Subnet mask) 3 (Routers) 28 (Broadcast address) 120 (SIP Servers DHCP Option) OPTION: 57 ( 2) Maximum DHCP message size 576 TIME: 2009-10-30 12:15:34.922 IP: 0.0.0.0 (1:22:33:44:55:66) 255.255.255.255 (ff:ff:ff:ff:ff:ff) OP: 1 (BOOTPREQUEST) HTYPE: 1 (Ethernet) HLEN: 6 HOPS: 0 XID: c3f93d53 SECS: 2 FLAGS: 7f80 CIADDR: 0.0.0.0 YIADDR: 0.0.0.0 SIADDR: 0.0.0.0 GIADDR: 0.0.0.0 CHADDR: 11:22:33:44:55:66:00:00:00:00:00:00:00:00:00:00 SNAME: . FNAME: . OPTION: 53 ( 1) DHCP message type 1 (DHCPDISCOVER) OPTION: 50 ( 4) Request IP address 0.0.0.0 OPTION: 61 ( 7) Client-identifier 01:11:22:33:44:55:66 OPTION: 55 ( 7) Parameter Request List 12 (Host name) 6 (DNS server) 15 (Domainname) 1 (Subnet mask) 3 (Routers) 28 (Broadcast address) 120 (SIP Servers DHCP Option) OPTION: 57 ( 2) Maximum DHCP message size 576 TIME: 2009-10-30 12:15:34.923 IP: 192.168.5.1 (a:bb:cc:dd:ee:ff) 255.255.255.255 (ff:ff:ff:ff:ff:ff) OP: 2 (BOOTPREPLY) HTYPE: 1 (Ethernet) HLEN: 6 HOPS: 0 XID: c3f93d53 SECS: 2 FLAGS: 7f80 CIADDR: 0.0.0.0 YIADDR: 192.168.5.21 SIADDR: 192.168.5.1 GIADDR: 0.0.0.0 CHADDR: 11:22:33:44:55:66:00:00:00:00:00:00:00:00:00:00 SNAME: . FNAME: . OPTION: 53 ( 1) DHCP message type 2 (DHCPOFFER) OPTION: 54 ( 4) Server identifier 192.168.5.1 OPTION: 51 ( 4) IP address leasetime 18000 (5h) OPTION: 58 ( 4) T1 9000 (2h30m) OPTION: 59 ( 4) T2 15750 (4h22m30s) OPTION: 1 ( 4) Subnet mask 255.255.255.0 OPTION: 28 ( 4) Broadcast address 192.168.5.255 OPTION: 3 ( 4) Routers 192.168.5.1 OPTION: 6 ( 4) DNS server 192.168.5.1 OPTION: 15 ( 8) Domainname home.pvt OPTION: 12 ( 3) Host name Nokia_E63 TIME: 2009-10-30 12:15:38.919 IP: 0.0.0.0 (1:22:33:44:55:66) 255.255.255.255 (ff:ff:ff:ff:ff:ff) OP: 1 (BOOTPREQUEST) HTYPE: 1 (Ethernet) HLEN: 6 HOPS: 0 XID: c3f93d53 SECS: 6 FLAGS: 7f80 CIADDR: 0.0.0.0 YIADDR: 0.0.0.0 SIADDR: 0.0.0.0 GIADDR: 0.0.0.0 CHADDR: 11:22:33:44:55:66:00:00:00:00:00:00:00:00:00:00 SNAME: . FNAME: . OPTION: 53 ( 1) DHCP message type 1 (DHCPDISCOVER) OPTION: 50 ( 4) Request IP address 0.0.0.0 OPTION: 61 ( 7) Client-identifier 01:11:22:33:44:55:66 OPTION: 55 ( 7) Parameter Request List 12 (Host name) 6 (DNS server) 15 (Domainname) 1 (Subnet mask) 3 (Routers) 28 (Broadcast address) 120 (SIP Servers DHCP Option) OPTION: 57 ( 2) Maximum DHCP message size 576 TIME: 2009-10-30 12:15:38.920 IP: 0.0.0.0 (1:22:33:44:55:66) 255.255.255.255 (ff:ff:ff:ff:ff:ff) OP: 1 (BOOTPREQUEST) HTYPE: 1 (Ethernet) HLEN: 6 HOPS: 0 XID: c3f93d53 SECS: 6 FLAGS: 7f80 CIADDR: 0.0.0.0 YIADDR: 0.0.0.0 SIADDR: 0.0.0.0 GIADDR: 0.0.0.0 CHADDR: 11:22:33:44:55:66:00:00:00:00:00:00:00:00:00:00 SNAME: . FNAME: . OPTION: 53 ( 1) DHCP message type 1 (DHCPDISCOVER) OPTION: 50 ( 4) Request IP address 0.0.0.0 OPTION: 61 ( 7) Client-identifier 01:11:22:33:44:55:66 OPTION: 55 ( 7) Parameter Request List 12 (Host name) 6 (DNS server) 15 (Domainname) 1 (Subnet mask) 3 (Routers) 28 (Broadcast address) 120 (SIP Servers DHCP Option) OPTION: 57 ( 2) Maximum DHCP message size 576 TIME: 2009-10-30 12:15:38.921 IP: 192.168.5.1 (a:bb:cc:dd:ee:ff) 255.255.255.255 (ff:ff:ff:ff:ff:ff) OP: 2 (BOOTPREPLY) HTYPE: 1 (Ethernet) HLEN: 6 HOPS: 0 XID: c3f93d53 SECS: 6 FLAGS: 7f80 CIADDR: 0.0.0.0 YIADDR: 192.168.5.21 SIADDR: 192.168.5.1 GIADDR: 0.0.0.0 CHADDR: 11:22:33:44:55:66:00:00:00:00:00:00:00:00:00:00 SNAME: . FNAME: . OPTION: 53 ( 1) DHCP message type 2 (DHCPOFFER) OPTION: 54 ( 4) Server identifier 192.168.5.1 OPTION: 51 ( 4) IP address leasetime 18000 (5h) OPTION: 58 ( 4) T1 9000 (2h30m) OPTION: 59 ( 4) T2 15750 (4h22m30s) OPTION: 1 ( 4) Subnet mask 255.255.255.0 OPTION: 28 ( 4) Broadcast address 192.168.5.255 OPTION: 3 ( 4) Routers 192.168.5.1 OPTION: 6 ( 4) DNS server 192.168.5.1 OPTION: 15 ( 8) Domainname home.pvt OPTION: 12 ( 3) Host name Nokia_E63 TIME: 2009-10-30 12:15:46.944 IP: 0.0.0.0 (1:22:33:44:55:66) 255.255.255.255 (ff:ff:ff:ff:ff:ff) OP: 1 (BOOTPREQUEST) HTYPE: 1 (Ethernet) HLEN: 6 HOPS: 0 XID: ccafe769 SECS: 14 FLAGS: 7f80 CIADDR: 0.0.0.0 YIADDR: 0.0.0.0 SIADDR: 0.0.0.0 GIADDR: 0.0.0.0 CHADDR: 11:22:33:44:55:66:00:00:00:00:00:00:00:00:00:00 SNAME: . FNAME: . OPTION: 53 ( 1) DHCP message type 1 (DHCPDISCOVER) OPTION: 50 ( 4) Request IP address 0.0.0.0 OPTION: 61 ( 7) Client-identifier 01:11:22:33:44:55:66 OPTION: 55 ( 7) Parameter Request List 12 (Host name) 6 (DNS server) 15 (Domainname) 1 (Subnet mask) 3 (Routers) 28 (Broadcast address) 120 (SIP Servers DHCP Option) OPTION: 57 ( 2) Maximum DHCP message size 576 TIME: 2009-10-30 12:15:46.944 IP: 0.0.0.0 (1:22:33:44:55:66) 255.255.255.255 (ff:ff:ff:ff:ff:ff) OP: 1 (BOOTPREQUEST) HTYPE: 1 (Ethernet) HLEN: 6 HOPS: 0 XID: ccafe769 SECS: 14 FLAGS: 7f80 CIADDR: 0.0.0.0 YIADDR: 0.0.0.0 SIADDR: 0.0.0.0 GIADDR: 0.0.0.0 CHADDR: 11:22:33:44:55:66:00:00:00:00:00:00:00:00:00:00 SNAME: . FNAME: . OPTION: 53 ( 1) DHCP message type 1 (DHCPDISCOVER) OPTION: 50 ( 4) Request IP address 0.0.0.0 OPTION: 61 ( 7) Client-identifier 01:11:22:33:44:55:66 OPTION: 55 ( 7) Parameter Request List 12 (Host name) 6 (DNS server) 15 (Domainname) 1 (Subnet mask) 3 (Routers) 28 (Broadcast address) 120 (SIP Servers DHCP Option) OPTION: 57 ( 2) Maximum DHCP message size 576 TIME: 2009-10-30 12:15:46.945 IP: 192.168.5.1 (a:bb:cc:dd:ee:ff) 255.255.255.255 (ff:ff:ff:ff:ff:ff) OP: 2 (BOOTPREPLY) HTYPE: 1 (Ethernet) HLEN: 6 HOPS: 0 XID: ccafe769 SECS: 14 FLAGS: 7f80 CIADDR: 0.0.0.0 YIADDR: 192.168.5.21 SIADDR: 192.168.5.1 GIADDR: 0.0.0.0 CHADDR: 11:22:33:44:55:66:00:00:00:00:00:00:00:00:00:00 SNAME: . FNAME: . OPTION: 53 ( 1) DHCP message type 2 (DHCPOFFER) OPTION: 54 ( 4) Server identifier 192.168.5.1 OPTION: 51 ( 4) IP address leasetime 18000 (5h) OPTION: 58 ( 4) T1 9000 (2h30m) OPTION: 59 ( 4) T2 15750 (4h22m30s) OPTION: 1 ( 4) Subnet mask 255.255.255.0 OPTION: 28 ( 4) Broadcast address 192.168.5.255 OPTION: 3 ( 4) Routers 192.168.5.1 OPTION: 6 ( 4) DNS server 192.168.5.1 OPTION: 15 ( 8) Domainname home.pvt OPTION: 12 ( 3) Host name Nokia_E63 TIME: 2009-10-30 12:15:48.952 IP: 0.0.0.0 (1:22:33:44:55:66) 255.255.255.255 (ff:ff:ff:ff:ff:ff) OP: 1 (BOOTPREQUEST) HTYPE: 1 (Ethernet) HLEN: 6 ... and so on ...

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  • Windows 2008 R2 DHCP server not responding to DHCP discover

    - by MartinSteel
    I've got two Windows 2008 Enterprise R2 servers both running DNS and DHCP called cod & lobster. DHCP is setup using the split scope option introduced with 2008 R2, whereby both servers should respond with the first response providing the lease. Setup is as follows: Cod - IP: 192.168.0.231 - Pool: 192.168.0.101 - 192.168.0.179, exclusion for 160-179. - Response Delay: 0ms - Authorised in Active Directory (Re-authorised to confirm) - Windows firewall disabled while testing Lobster - IP: 192.168.0.232 - Pool: 192.168.0.101 - 192.168.0.179, exclusion for 101-159. - Response Delay: 1000ms - Authorised in Active Directory All DHCP leases to clients are currently being issues by Lobster rather than Cod. Packet captures with Wireshark show the following (all to broadcast address): Client - DHCP Discover Lobster - DHCP Offer (after 1s delay) Client - DHCP Request Lobster - DHCP Ack Client - DHCP Inform From my setup with two servers I'd expect to see a DHCP Offer coming from Cod almost immediately after the DHCP Discover. Does anybody have any idea what would prevent the DHCP Server responding to the discover?

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  • Installing a DHCP Service On Win2k8 ( Windows Server 2008 )

    - by Akshay Deep Lamba
    Introduction Dynamic Host Configuration Protocol (DHCP) is a core infrastructure service on any network that provides IP addressing and DNS server information to PC clients and any other device. DHCP is used so that you do not have to statically assign IP addresses to every device on your network and manage the issues that static IP addressing can create. More and more, DHCP is being expanded to fit into new network services like the Windows Health Service and Network Access Protection (NAP). However, before you can use it for more advanced services, you need to first install it and configure the basics. Let’s learn how to do that. Installing Windows Server 2008 DHCP Server Installing Windows Server 2008 DCHP Server is easy. DHCP Server is now a “role” of Windows Server 2008 – not a windows component as it was in the past. To do this, you will need a Windows Server 2008 system already installed and configured with a static IP address. You will need to know your network’s IP address range, the range of IP addresses you will want to hand out to your PC clients, your DNS server IP addresses, and your default gateway. Additionally, you will want to have a plan for all subnets involved, what scopes you will want to define, and what exclusions you will want to create. To start the DHCP installation process, you can click Add Roles from the Initial Configuration Tasks window or from Server Manager à Roles à Add Roles. Figure 1: Adding a new Role in Windows Server 2008 When the Add Roles Wizard comes up, you can click Next on that screen. Next, select that you want to add the DHCP Server Role, and click Next. Figure 2: Selecting the DHCP Server Role If you do not have a static IP address assigned on your server, you will get a warning that you should not install DHCP with a dynamic IP address. At this point, you will begin being prompted for IP network information, scope information, and DNS information. If you only want to install DHCP server with no configured scopes or settings, you can just click Next through these questions and proceed with the installation. On the other hand, you can optionally configure your DHCP Server during this part of the installation. In my case, I chose to take this opportunity to configure some basic IP settings and configure my first DHCP Scope. I was shown my network connection binding and asked to verify it, like this: Figure 3: Network connection binding What the wizard is asking is, “what interface do you want to provide DHCP services on?” I took the default and clicked Next. Next, I entered my Parent Domain, Primary DNS Server, and Alternate DNS Server (as you see below) and clicked Next. Figure 4: Entering domain and DNS information I opted NOT to use WINS on my network and I clicked Next. Then, I was promoted to configure a DHCP scope for the new DHCP Server. I have opted to configure an IP address range of 192.168.1.50-100 to cover the 25+ PC Clients on my local network. To do this, I clicked Add to add a new scope. As you see below, I named the Scope WBC-Local, configured the starting and ending IP addresses of 192.168.1.50-192.168.1.100, subnet mask of 255.255.255.0, default gateway of 192.168.1.1, type of subnet (wired), and activated the scope. Figure 5: Adding a new DHCP Scope Back in the Add Scope screen, I clicked Next to add the new scope (once the DHCP Server is installed). I chose to Disable DHCPv6 stateless mode for this server and clicked Next. Then, I confirmed my DHCP Installation Selections (on the screen below) and clicked Install. Figure 6: Confirm Installation Selections After only a few seconds, the DHCP Server was installed and I saw the window, below: Figure 7: Windows Server 2008 DHCP Server Installation succeeded I clicked Close to close the installer window, then moved on to how to manage my new DHCP Server. How to Manage your new Windows Server 2008 DHCP Server Like the installation, managing Windows Server 2008 DHCP Server is also easy. Back in my Windows Server 2008 Server Manager, under Roles, I clicked on the new DHCP Server entry. Figure 8: DHCP Server management in Server Manager While I cannot manage the DHCP Server scopes and clients from here, what I can do is to manage what events, services, and resources are related to the DHCP Server installation. Thus, this is a good place to go to check the status of the DHCP Server and what events have happened around it. However, to really configure the DHCP Server and see what clients have obtained IP addresses, I need to go to the DHCP Server MMC. To do this, I went to Start à Administrative Tools à DHCP Server, like this: Figure 9: Starting the DHCP Server MMC When expanded out, the MMC offers a lot of features. Here is what it looks like: Figure 10: The Windows Server 2008 DHCP Server MMC The DHCP Server MMC offers IPv4 & IPv6 DHCP Server info including all scopes, pools, leases, reservations, scope options, and server options. If I go into the address pool and the scope options, I can see that the configuration we made when we installed the DHCP Server did, indeed, work. The scope IP address range is there, and so are the DNS Server & default gateway. Figure 11: DHCP Server Address Pool Figure 12: DHCP Server Scope Options So how do we know that this really works if we do not test it? The answer is that we do not. Now, let’s test to make sure it works. How do we test our Windows Server 2008 DHCP Server? To test this, I have a Windows Vista PC Client on the same network segment as the Windows Server 2008 DHCP server. To be safe, I have no other devices on this network segment. I did an IPCONFIG /RELEASE then an IPCONFIG /RENEW and verified that I received an IP address from the new DHCP server, as you can see below: Figure 13: Vista client received IP address from new DHCP Server Also, I went to my Windows 2008 Server and verified that the new Vista client was listed as a client on the DHCP server. This did indeed check out, as you can see below: Figure 14: Win 2008 DHCP Server has the Vista client listed under Address Leases With that, I knew that I had a working configuration and we are done!

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  • Inconsistent DHCP replies with Windows 2008R2 DHCP server

    - by verbalicious
    I've got a Windows 2008R2 standard server running DHCP services. We've noticed that certain clients are receiving inconsistent DHCP replies. We have over 175 Windows workstations in this VLAN that don't seem to have trouble getting DHCP leases. However, PXE-booting clients trying to reach our DHCP server are able to get a lease inconsistently. Additionally, we tried using the "dhcping" tool against our DHCP server and found that roughly two of every three requests time out with "no answer" -- and this holds true when we set the timeout value on dhcping to 20seconds. After a failed attempt, however, we may get a dhcp lease reply immediately with dhcping. This leads me to believe that this issue isn't confined to PXE booting clients, but something more systemic with my LAN layer2 or DHCP. And that possibly my 175 windows clients are experiencing this in some form without my knowledge. We have over 30% of our scope available so the addresses are there. I was unable to find anything in the Windows server "DHCP-Server" log. Of course, my goal is to have my DHCP server reply to every request that it receives on the LAN!

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  • Can't Start ISC DHCP IPv6 Server

    - by MrDaniel
    Trying to enable the ISC DHCP server for just IPv6 on Ubuntu 12.04 LTS. I have downloaded and installed the DHCP server via the following command: $ sudo apt-get install isc-dhcp-server Then I have followed the instructions in the following resources, Ubuntu Wiki DHCPv6, SixXS - Configuring ISC DHCPv6 Server and Linux IPv6 HOWTO - Configuration of the ISC DHCP server for IPv6 . So from review all those resources it seems like I need to: set a static IPv6 address for the Interface I want to run the DHCPv6 server from that is part of the IPv6 network subnet outside the DHCP range. Edit the /etc/dhcp/dhcpd6.conf file to configure the DHCPv6 range etc. Create the /var/lib/dhcp/dhcpd6.leases Manually start the DHCPv6 server. Setting the Static IP for eth0 $ sudo ifconfig eth0 inet6 add 2001:db8:0:1::128/64 My dhcpd6.conf default-lease-time 600; max-lease-time 7200; log-facility local7; subnet6 2001:db8:0:1::/64 { #Range for clients range6 2001:db8:0:1::129 2001:db8:0:1::254; } Created the dhcpd6.leases file As indicated in the dhcpd.leases man page. $ touch /var/lib/dhcp/dhcpd6.leases #Tried with sudo as well Manually starting the DHCPv6 server. Attempted to start the server using the following command: $ sudo dhcp -6 -f -cf /etc/dhcp/dhcpd6.conf eth0 The problem, the DHCP will not start, with an append error for the dhcpd6.leases file as indicated below when running the manual start command noted above. Can't open /var/lib/dhcp/dhcpd6.leases for append. Any ideas what I might be missing?

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  • ASA DHCP Relay configuration..

    - by Jeff
    I have locations in different cities, connected using 2 Cisco ASA devices. my main location, corporate, use the IP 192.168.1.x The second location, remote store, use the IP 192.168.3.x I have a DHCP server (192.168.1.254) at my corporate location. I have created a scope for the 192.168.1.x which works fine for the corporate location. I created a scope for the remote location (192.168.3.x) on my DHCP server and tried to configure the remote ASA DCHP Relay, on the remote ASA: I disabled the DHCP Server on the inside. I enabled DHCP Relay on the inside, with set route set at yes. I set the Global DHCP Relay Servers, specify up to four servers to which DHCP requests would be relayed. I added my DHCP, 192.168.1.254 I flashed these settings to the ASA and gave it a try, didn't do anything. am i missing something - forgetting something. not really sure what im doing wrong. DHCP Settings on remote ASA: dhcp-client update dns server both dhcpd dns 192.168.1.254 dhcpd ping_timeout 750 dhcpd domain JEWELS.LOCAL dhcpd auto_config outside dhcpd update dns both ! dhcpd address 192.168.3.2-192.168.3.33 inside ! dhcprelay server 192.168.1.254 outside dhcprelay enable inside dhcprelay setroute inside on my local ASA: i have two ACLs for UDP ports 67 and 68 permitting any inbound traffic from the remote locations IP ... dhcprelay timeout 120

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  • Windows Vista DHCP bug, arp authorize, isc dhcp, workaround

    - by jinanwow
    I am trying to find a workaround for the Windows Vista Force Broadcast bug with ISC DHCP and a Cisco Router. The problem is not windows vista trying to obtain an IP address from us that works fine (with or without the flag enabled). THe problem is we are using a cisco router and the command 'arp authorized' to prevent users from using static IP addresses on the network. The problem is, if Windows Vista sets the boot flag to true the command 'arp authorized' will not work, as it looks for the IP address and destination MAC address in the DHCP Offer Packet to add it to its arp table. The machine will DHCP just fine, but since the ARP table is not aware of the machine, it is unable to access the internet. If I disable the broadcast flag in vista, the next time it DHCPs an arp entry gets created since the DHCP Offer is unicast instead of broadcast. The thing is, we can not tell 500 to 1000 people to edit their registry, so we need a workaround for this issue. I have not had much success in finding a workaround. The question is, is there a way to force or trick ISC DHCP into unicasting a responce back to the user. Either on the Cisco Side, ISC DHCP side or intercepting and rewriting the DHCP Discover UDP packet to turn off the flag before it reaches ISC DHCP?

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  • DHCP and DNS services configuration for VOIP system, windows domain, etc

    - by Stemen
    My company has numerous physical offices (for purposes of this discussion, 15 buildings). Some of them are well-connected to our primary data center via fiber. Others will be connected to the data center by P2P T1. We are in the beginning stages of implementing an Avaya VOIP telephone system, and we will be replacing a significant portion of our network infrastructure in the process. In tandem with the phone system implementation, we are going to be re-addressing some of our networks, and consolidating most of our Windows domains into one (not all domains, just most). We currently have quite a few Windows domains, and they of course each have their own DNS zones. A few of those networks currently use DHCP, but the majority use static IP assignments for every device. I'm tired of managing static assignments -- I want to use DHCP configuration on everything except servers. Printers and etc will have DHCP reservations. The new IP phones will need to get IP addresses from DHCP, though they need to be in a separate VLAN from the computers/printers/etc. The computers and printers need to be registered in DNS. That's currently handled by the Windows DHCP servers on each of the respective domains. We need to place a priority on DHCP and DNS being available on a per-site basis (in case something were to interrupt the WAN connection) for computers and (primarily) phones. Smaller locations (which will have IP phones but not be a member of any Windows domain) will not have any Windows DNS/DHCP server(s) available. We also are looking for the easiest way to replace a part if it were to fail. That is to say, if a server/appliance/router hosting DHCP were to crash hard, and we couldn't extremely quickly recover the DHCP reservations and leases (and subsequently restore them onto a cold spare), we anticipate that bad things could happen. What is the best idea for how to re-implement DNS and DHCP keeping all of the above in mind? Some thoughts that have been raised (by myself or my coworkers): Use Windows DNS and DHCP servers, where they exist, and use IP helpers to route DHCP requests to some other Windows server if necessary. May not be acceptable if the WAN goes down and clients don't get a DHCP response. Use Windows DNS (everywhere, over WAN in some cases) and a mix of Windows DHCP and DHCP provided by Cisco routers. Every site would be covered for DHCP, but from what I've read, Cisco routers can't handle dynamic registration of DHCP clients to Windows DNS servers, which might create a problem where Cisco routers are used for DHCP. Use Windows DNS (everywhere, over WAN in some cases) and a mix of Windows DHCP and DHCP provided by some service running on an extremely low-price linux server. Is there any such software that would allow DHCP leases granted by these linux boxes to be dynamically registered on the Windows DNS servers? Come up with a Linux solution for both DNS and DHCP, and deploy low-price linux servers to every site. Requirements would be that the DNS zone be multi-master (like Windows DNS integrated with Active Directory), that DHCP be able to make dynamic DNS registrations in that zone, for every lease (where a hostname is provided and is thus possible), and that multiple servers be either authoritative for the same DHCP scope or at least receiving a real-time copy / replication / sync of the leases table so that if one server dies, we still know which MAC has what address. Purchase dedicated DNS/DHCP appliances, deploying to all sites. From what I read/see, this solves all of our technical problems. Then come the financial problems... I don't have a ton of money to spend on this. Or, some other solution that we've thus far overlooked and will consider upon recommendation. Can Cisco routers or Windows servers sync DHCP lease tables so that multiple servers can be authoritative (or active/passive for all I care) for the same scope, in case one of the partners were to fail? I've read online (repeatedly) that ISC's DHCP is able to maintain the same lease table across multiple servers, in order to solve this problem. Does anyone have any experience or advice to regarding that?

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  • What does a DHCP-client consider to be the "best" answer?

    - by Nils
    We have training rooms where normally Windows XP is installed (via PXE). The "normal" DNS/DHCP infrastructure are Windows-Servers. The training room has its own VLAN (different from the Windows servers), so there is most propably an IP helper for DHCP requests active on the Cisco router where all PCs from that room are connected to. Now we wanted to convert some of the PCs to Linux instead. The idea was: Put our own Laptop with a DHCP server into the VLAN of the room and override the "normal" DHCP response. The idea was that this should work, since a directly attached DHCP server in that VLAN should have a faster response-time than the "normal" DHCP server located some hops away from that VLAN. It turned out that this did not work. We had to manually release the lease on the original DHCP server to get it working. On the Laptop we did see the client requesting the IP and "our" dhcp was sending NACKs to the Windows IP request, before that we did offer our own response. Old Question: Why did this not work out as expected? What is making the PC regain its old lease? Update 2012-08-08: The regain-issue has been explained in the DHCP-RFC. Now this explains why the PC regains its old lease. Now we do release the IP from the Windows-DHCP-server before giving it another try. Again - the Windows-DHCP-server wins. I suspect that there is some algorithm for the dhcp-client which determines the "best" dhcp-answer for the client. The new question is: How does the client choose the "best" answer?

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  • Assign fixed IP address via DHCP by DNS lookup

    - by Janoszen
    Preface I'm building a virtualization environment with Ubuntu 14.04 and LXC. I don't want to write my own template since the upgrade from 12.04 to 14.04 has shown that backwards compatibility is not guaranteed. Therefore I'm deploying my virtual machines via lxc-create, using the default Ubuntu template. The DNS for the servers is provided by Amazon Route 53, so no local DNS server is needed. I also use Puppet to configure my servers, so I want to keep the manual effort on the deployment minimal. Now, the default Ubuntu template assigns IP addresses via DHCP. Therefore, I need a local DHCP server to assign IP addresses to the nodes, so I can SSH into them and get Puppet running. Since Puppet requires a proper DNS setup, assigning temporary IP addresses is not an option, the client needs to get the right hostname and IP address from the start. Question What DHCP server do I use and how do I get it to assign the IP address based only on the host-name DHCP option by performing a DNS lookup on that very host name? What I've tried I tried to make it work using the ISC DHCP server, however, the manual clearly states: Please be aware that only the dhcp-client-identifier option and the hardware address can be used to match a host declaration, or the host-identifier option parameter for DHCPv6 servers. For example, it is not possible to match a host declaration to a host-name option. This is because the host-name option cannot be guaranteed to be unique for any given client, whereas both the hardware address and dhcp-client-identifier option are at least theoretically guaranteed to be unique to a given client. I also tried to create a class that matches the hostname like this: class "my-client-name" { match if option host-name = "my-client-name"; fixed-address my-client-name.my-domain.com; } Unfortunately the fixed-address option is not allowed in class statements. I can replace it with a 1-size pool, which works as expected: subnet 10.103.0.0 netmask 255.255.0.0 { option routers 10.103.1.1; class "my-client-name" { match if option host-name = "my-client-name"; } pool { allow members of "my-client-name"; range 10.103.1.2 10.103.1.2; } } However, this would require me to administer the IP addresses in two places (Amazon Route53 and the DHCP server), which I would prefer not to do. About security Since this is only used in the bootstrapping phase on an internal network and is then replaced by a static network configuration by Puppet, this shouldn't be an issue from a security standpoint. I am, however, aware that the virtual machine bootstraps with "ubuntu:ubuntu" credentials, which I intend to fix once this is running.

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  • Assign fixed IP address via DHCP by DNS lookup

    - by Janoszen
    Preface I'm building a virtualization environment with Ubuntu 14.04 and LXC. I don't want to write my own template since the upgrade from 12.04 to 14.04 has shown that backwards compatibility is not guaranteed. Therefore I'm deploying my virtual machines via lxc-create, using the default Ubuntu template. The DNS for the servers is provided by Amazon Route 53, so no local DNS server is needed. I also use Puppet to configure my servers, so I want to keep the manual effort on the deployment minimal. Now, the default Ubuntu template assigns IP addresses via DHCP. Therefore, I need a local DHCP server to assign IP addresses to the nodes, so I can SSH into them and get Puppet running. Since Puppet requires a proper DNS setup, assigning temporary IP addresses is not an option, the client needs to get the right hostname and IP address from the start. Question What DHCP server do I use and how do I get it to assign the IP address based only on the host-name DHCP option by performing a DNS lookup on that very host name? What I've tried I tried to make it work using the ISC DHCP server, however, the manual clearly states: Please be aware that only the dhcp-client-identifier option and the hardware address can be used to match a host declaration, or the host-identifier option parameter for DHCPv6 servers. For example, it is not possible to match a host declaration to a host-name option. This is because the host-name option cannot be guaranteed to be unique for any given client, whereas both the hardware address and dhcp-client-identifier option are at least theoretically guaranteed to be unique to a given client. I also tried to create a class that matches the hostname like this: class "my-client-name" { match if option host-name = "my-client-name"; fixed-address my-client-name.my-domain.com; } Unfortunately the fixed-address option is not allowed in class statements. I can replace it with a 1-size pool, which works as expected: subnet 10.103.0.0 netmask 255.255.0.0 { option routers 10.103.1.1; class "my-client-name" { match if option host-name = "my-client-name"; } pool { allow members of "my-client-name"; range 10.103.1.2 10.103.1.2; } } However, this would require me to administer the IP addresses in two places (Amazon Route53 and the DHCP server), which I would prefer not to do. About security Since this is only used in the bootstrapping phase on an internal network and is then replaced by a static network configuration by Puppet, this shouldn't be an issue from a security standpoint. I am, however, aware that the virtual machine bootstraps with "ubuntu:ubuntu" credentials, which I intend to fix once this is running.

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  • Multiple subnets on isc-dhcp-server using ddns with bind9

    - by legioxi
    On my network I have two subnets: 10.100.1.0/24 - Wired/wireless 10.100.7.0/24 - VPN Both subnets are served by isc-dhcp-server running on a Debian VM. This same VM runs bind9 for my DNS. ISC-DHCP-SERVER is configured to use DDNS and update BIND9 with hosts/IPs. Everything runs great until a device drops off the wired/wireless network and pops onto the VPN. When connecting on the VPN, a DHCP lease is handed out on the new subnet but DDNS does not update BIND9. Since the device has A/TXT/PTR records it appears ISC-DHCP-SERVER won't switch them to the new IP. The logs show: Connect to wireless: Nov 6 20:55:13 core-server named[2417]: client 127.0.0.1#57697: updating zone 'internal.mydomain.com/IN': adding an RR at 'demo-iphone.internal.mydomain.com' A Nov 6 20:55:13 core-server named[2417]: client 127.0.0.1#57697: updating zone 'internal.mydomain.com/IN': adding an RR at 'demo-iphone.internal.mydomain.com' TXT Nov 6 20:55:13 core-server dhcpd: DHCPACK on 10.100.1.160 to FF:FF:FF:FF:FF:FF (demo-iphone) via eth0 Nov 6 20:55:13 core-server dhcpd: Added new forward map from demo-iphone.internal.mydomain.com to 10.100.1.160 Nov 6 20:55:13 core-server dhcpd: Added reverse map from 160.49.21.172.in-addr.arpa. to demo-iphone.internal.mydomain.com Switch to VPN: Nov 6 20:56:34 core-server dhcpd: DHCPOFFER on 10.100.7.101 to BB:BB:BB:BB:BB:BB (demo-iphone) via 10.100.7.0 Nov 6 20:56:34 core-server named[2417]: client 127.0.0.1#57697: updating zone 'internal.mydomain.com/IN': update unsuccessful: demo-iphone.internal.mydomain.com: 'name not in use' prerequisite not satisfied (YXDOMAIN) Nov 6 20:56:34 core-server dhcpd: DHCPREQUEST for 10.100.7.101 (10.100.1.2) from BB:BB:BB:BB:BB:BB (demo-iphone) via 10.100.7.0 Nov 6 20:56:34 core-server dhcpd: DHCPACK on 10.100.7.101 to BB:BB:BB:BB:BB:BB (demo-iphone) via 10.100.7.0 Nov 6 20:56:34 core-server named[2417]: client 127.0.0.1#57697: updating zone 'internal.mydomain.com/IN': update unsuccessful: demo-iphone.internal.mydomain.com/TXT: 'RRset exists (value dependent)' prerequisite not satisfied (NXRRSET) Nov 6 20:56:34 core-server dhcpd: Forward map from demo-iphone.internal.mydomain.com to 10.100.7.101 FAILED: Has an address record but no DHCID, not mine. One thing to note is that the MAC of the device when connecting via VPN is the MAC of my Cisco ASA5512X and not the actual device. The ASA is relaying the DHCP request from the VPN client to the VM running ISC-DHCP-SERVER. Is there a way to get DDNS working in this scenario?

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  • Is the native DHCP client for MacOS X able to send "Vendor class identifier" (opTag 60) in a DHCP request?

    - by plluksie
    Is it possible for MacOS X (current version or in any previous one) to easily force DHCP client to send to DHCP server, at the beggining of the conversation - in DHCPDISCOVER packet - option "Vendor Class Identifier" (60) set to some value? I know that I can install i.e. ISC DHCP client through pkgsrc which supports VCI, but I'm looking for something native. Thank you in advance for information.

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  • DHCP Client Can't Find DHCP Server

    - by leeman24
    I currently have 3 machines: CentOS (router) eth1 - 18.0.168.1 eth2 - 145.165.34.1 Windows Server 2008 (server) 18.0.168.2 DHCP scope - 145.165.34.10 - 145.165.34.20 Windows 7 (client) Supposed to use DHCP I can't get my Windows 7 client to get an address from the Windows Server 2008 DHCP server. Every network interface can ping each other (ex. 18.0.168.2 can ping 18.0.168.1 & 145.165.34.1 and the other way around). My Linux machine acting as the router has default IP tables. Other than this command which may or may not be right: iptables -I INPUT -p udp -d 18.0.168.2 --dport 67:68 -j ACCEPT I have also tried it after I flushed the IP tables. I was looking at the dhcrelay command but it seems CentOS doesn't have it and I am not even sure how to use it.

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  • DHCP server not starting

    - by Bruce
    I'm trying to set a DHCP server on 12.04. I installed: sudo apt-get install isc-dhcp-server My configuration files look like this: /etc/default/isc-dhcp-server INTERFACES="eth0" /etc/network/interfaces auto lo iface lo inet loopback /etc/dhcp/dhcpd.conf ddns-update-style none; default-lease-time 600; max-lease-time 7200; authoritative; log-facility local7; subnet 192.168.1.0 netmask 255.255.255.0 { range 192.168.1.235 192.168.1.240; option subnet-mask 255.255.255.0; option broadcast-address 192.168.1.255; option routers 192.168.1.1; default-lease-time 100000; max-lease-time 100000; } When I run sudo service isc-dhcp-server restart I get: stop: Unknown instance: isc-dhcp-server start/running, process 15384 After this if I run sudo service isc-dhcp-server status it shows that its stopped: isc-dhcp-server stop/waiting What am I doing wrong here?

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  • Windows DHCP Server - get notification when a non-AD joined device gets an IP address

    - by TheCleaner
    SCENARIO To simplify this down to it's easiest example: I have a Windows 2008 R2 standard DC with the DHCP server role. It hands out IPs via various IPv4 scopes, no problem there. WHAT I'D LIKE I would like a way to create a notification/eventlog entry/similar whenever a device gets a DHCP address lease and that device IS NOT a domain joined computer in Active Directory. It doesn't matter to me whether it is custom Powershell, etc. Bottom line = I'd like a way to know when non-domain devices are on the network without using 802.1X at the moment. I know this won't account for static IP devices. I do have monitoring software that will scan the network and find devices, but it isn't quite this granular in detail. RESEARCH DONE/OPTIONS CONSIDERED I don't see any such possibilities with the built in logging. Yes, I'm aware of 802.1X and have the ability to implement it long-term at this location but we are some time away from a project like that, and while that would solve network authentication issues, this is still helpful to me outside of 802.1X goals. I've looked around for some script bits, etc. that might prove useful but the things I'm finding lead me to believe that my google-fu is failing me at the moment. I believe the below logic is sound (assuming there isn't some existing solution): Device receives DHCP address Event log entry is recorded (event ID 10 in the DHCP audit log should work (since a new lease is what I'd be most interested in, not renewals): http://technet.microsoft.com/en-us/library/dd759178.aspx) At this point a script of some kind would probably have to take over for the remaining "STEPS" below. Somehow query this DHCP log for these event ID 10's (I would love push, but I'm guessing pull is the only recourse here) Parse the query for the name of the device being assigned the new lease Query AD for the device's name IF not found in AD, send a notification email If anyone has any ideas on how to properly do this, I'd really appreciate it. I'm not looking for a "gimme the codez" but would love to know if there are alternatives to the above list or if I'm not thinking clear and another method exists for gathering this information. If you have code snippets/PS commands you'd like to share to help accomplish this, all the better.

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  • How to run a DHCP service on Windows 7 Home

    - by Joshua Lim
    I'm trying to setup a DHCP server on Windows 7 Home, tried using a couple of freeware which I found on the Internet but none seemed to work. What I did: On the Windows 7 machine which I install the DHCP Server with the range 192.168.1.12-192.168.1.256. I set the Gigabit Ethernet adapter to a static IP address of 192.168.1.11 and subnet mask of 255.255.255.0. When I did an IP config, it showed. Ethernet adapter Local Area Connection: Connection-specific DNS Suffix . : Description . . . . . . . . . . . : Broadcom NetLink (TM) Gigabit Ethernet Physical Address. . . . . . . . . : 8C-73-6E-75-A7-56 DHCP Enabled. . . . . . . . . . . : No Autoconfiguration Enabled . . . . : Yes Link-local IPv6 Address . . . . . : fe80::196d:b6bb:8f93:2555%12(Preferred) IPv4 Address. . . . . . . . . . . : 192.168.1.11(Preferred) Subnet Mask . . . . . . . . . . . : 255.255.255.0 Default Gateway . . . . . . . . . : DNS Servers . . . . . . . . . . . : fec0:0:0:ffff::1%1 fec0:0:0:ffff::2%1 fec0:0:0:ffff::3%1 NetBIOS over Tcpip. . . . . . . . : Enabled I connected another Window 7 machine to the "DHCP server" using a cross cable and set network adapter on that machine to automatically detect IP address. The client fails to acquire the correct IP address from the DHCP server and showed the autoconfigured IPv4 address instead. Here's the information returned by config /all on the client machine. Ethernet adapter Local Area Connection: Connection-specific DNS Suffix . : Description . . . . . . . . . . . : Atheros AR8152/8158 PCI-E Fast Ethernet Controller (NDIS 6.20) Physical Address. . . . . . . . . : 54-04-A6-40-96-4B DHCP Enabled. . . . . . . . . . . : Yes Autoconfiguration Enabled . . . . : Yes Link-local IPv6 Address . . . . . : fe80::4885:4082:5572:5a85%12(Preferred) Autoconfiguration IPv4 Address. . : 169.254.90.133(Preferred) Subnet Mask . . . . . . . . . . . : 255.255.0.0 Default Gateway . . . . . . . . . : DHCPv6 IAID . . . . . . . . . . . : 341050534 DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-17-54-78-12-00-08-CA-46-4C-5A DNS Servers . . . . . . . . . . . : fec0:0:0:ffff::1%1 fec0:0:0:ffff::2%1 fec0:0:0:ffff::3%1 NetBIOS over Tcpip. . . . . . . . : Enabled DHCP client are running on both machines. I've tried many times but failed. Googling also returned no useful information for my scenario. Have I missed out any step? Thanks.

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  • DHCP won't start / subnetting

    - by user114371
    I recently changed the IP address on an Ubuntu 12.04 server I have in my lab, which is running isc-dhcp-server. After doing so and modifying the dhcpd.conf file, my dhcp service would not start. I basically used the same configuration, except I modified everything to use /25 scopes rather than /24. When I try to start / restart the service, I see the following: [email protected]:~$ sudo service isc-dhcp-server restart stop: Unknown instance: isc-dhcp-server start/running, process 20918 It looks like it starts, but it isn't actually running and Webmin states that the DHCP service is not running. So my question is, does isc-dhcp-server support subnetting (CIDR) style scopes, or must they be class A / B / C scopes (doesn't seem likely)? I've double checked the interface reference (this is a VM with only one defined eth0 interface) and everything else I can thing of.

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  • Could not find DHCP daemon to get information on Belkin G Wifi Router

    - by Anirudh Goel
    I am using a Belkin G Wireless Router F5D7234, and i have a DSL connection with only a ethernet cable. So i connected the cable to the Modem port and allowed it to use Dyanmic IP, it worked successfully and an ip was assigned to it and multiple computers could connect to it and browse. But after some time the power went off and after then upon rebooting it is taking about half hour to get an IP address. Upon seeing the log i see this entry repeatedly 07/02/2010 23:22:34 DHCP Client: [WAN]Could not find DHCP daemon to get information 07/02/2010 23:22:32 DHCP Client: [WAN]Send Discover 07/02/2010 23:22:30 DHCP Client: [WAN]Send Discover 07/02/2010 23:22:28 DHCP Client: [WAN]Send Discover 07/02/2010 23:22:26 DHCP Client: [WAN]Send Discover 07/02/2010 23:22:26 DHCP Client: [WAN]Could not find DHCP daemon to get information 07/02/2010 23:22:24 DHCP Client: [WAN]Send Discover 07/02/2010 23:22:22 DHCP Client: [WAN]Send Discover 07/02/2010 23:22:20 DHCP Client: [WAN]Send Discover 07/02/2010 23:22:18 DHCP Client: [WAN]Send Discover Any idea what i can do? I tried using another belkin router of same model and make and there also i faced the same problem.

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  • Aliased network interfaces and isc dhcp server

    - by Jonatan
    I have been banging my head on this for a long time now. There are many discussions on the net about this and similar problems, but none of the solutions seems to work for me. I have a Debian server with two ethernet network interfaces. One of them is connected to internet, while the other is connected to my LAN. The LAN network is 10.11.100.0 (netmask 255.255.255.0). We have some custom hardware that use network 10.4.1.0 (netmask 255.255.255.0) and we can't change that. But we need all hosts on 10.11.100.0 to be able to connect to devices on 10.4.1.0. So I added an alias for the LAN network interface so that the Debian server acts as a gateway between 10.11.100.0 and 10.4.1.0. But then the dhcp server stopped working. The log says: No subnet declaration for eth1:0 (no IPv4 addresses). ** Ignoring requests on eth1:0. If this is not what you want, please write a subnet declaration in your dhcpd.conf file for the network segment to which interface eth1:1 is attached. ** No subnet declaration for eth1:1 (no IPv4 addresses). ** Ignoring requests on eth1:1. If this is not what you want, please write a subnet declaration in your dhcpd.conf file for the network segment to which interface eth1:1 is attached. ** I had another server before, also running Debian but with the older dhcp3 server, and it worked without any problems. I've tried everything I can think of in dhcpd.conf etc, and I've also compared with the working configuration in the old server. The dhcp server need only handle devices on 10.11.100.0. Any hints? Here's all relevant config files: /etc/default/isc-dhcp-server INTERFACES="eth1" /etc/network/interfaces (I've left out eth0, that connects to the Internet, since there is no problem with that.) auto eth1:0 iface eth1:0 inet static address 10.11.100.202 netmask 255.255.255.0 auto eth1:1 iface eth1:1 inet static address 10.4.1.248 netmask 255.255.255.0 /etc/dhcp/dhcpd.conf ddns-update-style none; option domain-name "???.com"; option domain-name-servers ?.?.?.?; default-lease-time 86400; max-lease-time 604800; authorative; subnet 10.11.100.0 netmask 255.255.255.0 { option subnet-mask 255.255.255.0; pool { range 10.11.100.50 10.11.100.99; } option routers 10.11.100.102; } I have tried to add shared-network etc, but didn't manage to get that to work. I get the same error message no matter what...

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  • setup Mac Book Wifi interface as Wifi hotspot using specific DHCP option

    - by srjohnhuang
    I want to using my Mac Book as an access point. Besides that I also need to configure its DHCP server to not provide DNS info. For example, Mac Books AP's ssid is "MacBookHotspot". While my iPhone connected to "MacBookHotspot", I want the Wifi info displayed my iPhone would be looked like: IP ADDRESS DHCP(tab) IP Address 192.168.0.1 Subnet Mask 255.255.255.0 Router 192.168.0.254 DNS Search Domains Client ID (key point: DNS filed is blank) Does anyone have any good suggestion? Thanks!

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  • DHCP Relay V DHCP Local Cisoc v 3com

    - by DefSol
    Howdy, I have a client who has a WAN with 7 sites. At one site in particular, randomly about 4-5 clients do not get an IP address. The local gateway is a cisco 871 and relay's to a windows server in a Data Center running a valid scope for the subnet. If I put in a cisco 1800 and configure a dhcp scope (disabling the scope on the server) all clients get an ip address and everything is right with the world. The Wan providing keeps saying it's a local issue although we can work around with the 1800. The provider says a 3Com switch is at fault and the 1800 does not have a local switch, and because the 871 does, means the internal switching will receive a different uplink policy. The 3Com is the only managed switch in the subnet. Any ideas greatly appreciated. Reuben

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  • DHCP Relay V DHCP Local Cisco v 3com

    - by DefSol
    Howdy, I have a client who has a WAN with 7 sites. At one site in particular, randomly about 4-5 clients do not get an IP address. The local gateway is a cisco 871 and relay's to a windows server in a Data Center running a valid scope for the subnet. If I put in a cisco 1800 and configure a dhcp scope (disabling the scope on the server) all clients get an ip address and everything is right with the world. The Wan providing keeps saying it's a local issue although we can work around with the 1800. The provider says a 3Com switch is at fault and the 1800 does not have a local switch, and because the 871 does, means the internal switching will receive a different uplink policy. The 3Com is the only managed switch in the subnet. Any ideas greatly appreciated. Reuben

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