domingo, 20 de setembro de 2015

Mikrotik - Configurar DHCP OPTION para CAPSMAN


DHCP with CAPsMAN

Even though it was clearly said in a documentation, I felt like checking it out by myself anyway.

Wireshark snippet


    Option: (53) DHCP Message Type (ACK)
        Length: 1
        DHCP: ACK (5)
    Option: (54) DHCP Server Identifier
        Length: 4
        DHCP Server Identifier: 192.168.7.95 (192.168.7.95)
    Option: (51) IP Address Lease Time
        Length: 4
        IP Address Lease Time: (180s) 3 minutes
    Option: (1) Subnet Mask
        Length: 4
        Subnet Mask: 255.255.252.0 (255.255.252.0)
    Option: (3) Router
        Length: 4
        Router: 192.168.7.1 (192.168.7.1)
    Option: (6) Domain Name Server
        Length: 4
        Domain Name Server: 1.2.3.4 (1.2.3.4)
    Option: (42) Network Time Protocol Servers
        Length: 12
        Network Time Protocol Server: 192.168.100.250 (192.168.100.250)
        Network Time Protocol Server: 192.168.100.251 (192.168.100.251)
        Network Time Protocol Server: 192.168.7.1 (192.168.7.1)
    Option: (138) CAPWAP Access Controllers
        Length: 4
        CAPWAP Access Controllers: 192.168.7.95 (192.168.7.95)
    Option: (255) End
        Option End: 255
    Padding

Raw data snippet
8a 04 c0 a8 07 5f


Where:
  • 0x8a = 138 (CAPWAP Access Controllers)
  • 0x04 = 4 (length)
  • 0xc0 = 192 (IP address of CAPsMAN was 192.168.7.95)
  • 0xa8 = 168 
  • 0x07 = 7 
  • 0x5f = 95 


BTW: the DHCP DISCOVER asked about

    Option: (55) Parameter Request List
        Length: 7
        Parameter Request List Item: (1) Subnet Mask
        Parameter Request List Item: (121) Classless Static Route
        Parameter Request List Item: (3) Router
        Parameter Request List Item: (33) Static Route
        Parameter Request List Item: (6) Domain Name Server
        Parameter Request List Item: (42) Network Time Protocol Servers
        Parameter Request List Item: (138) CAPWAP Access Controllers

Yes, all of that with a configuration asking from a configuration just for

/ip dhcp-client
add disabled=no interface=ether1-gateway dhcp-option=hostname,clientid \
    default-route-distance=1 use-peer-dns=yes use-peer-ntp=yes 

ISP DHCP

If you wanted to use ISC DHCP server (because your surname is Vixie ;)), add

option mk-capwap code 138 = array of ip-address;

        host RB2011 {
                hardware ethernet 00:11:22:33:44:55;
                fixed-address 192.168.7.105;
                option ntp-servers 192.168.7.1,192.168.7.2;
                option mk-capwap 192.168.7.95;
        }

Last but not least

DHCP works with untagged VLAN.

Ingredients used


The test was conducted using
  • RouterOS 6.18 on both DHCP server and client
  • Internet Systems Consortium DHCP Server 4.2.4-P2




fonte:
http://alicevixie.blogspot.com.br/2014/08/isc-dhcp-capsman.html


Reações:

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