DHCP: Optionen

Posted on | By MasterNerd

Vielen Geräten im Netzwerk können mit dem DHCP Konfigurationsoptionen mitgegeben werden. Dazu gehören WLAN-APs, Telefone u.v.m. Eine Liste der möglichen Optionen findet sich am Ende dieses Textes. Dabei gibt es Optionen, die in ihrer Funktion schon festgelegt sind und solche die frei belegt werden können. Diese Werte sind nummeriert, können aber wie ein Variablenname angesprochen werden. Ein Beispiel dafür ist die hier verwendete Option 43. Dies ist eine vordefinierte Option mit der Nummer 43 und dem Namen ‘vendor-encapsulated-options’. Vordefiniert bedeutet, dass sie in einem Subnet ohne Deklaration direkt verwendet werden kann. Generell können die Options-Namen frei gewählt werden, jedoch empfiehlt es sich bei den vordefinierten Optionen beim RFC-konformen Namen zu bleiben.
Im Gegensatz dazu müssen nicht vorgegebene Optionen immer erst definiert werden. Da Optionen global für den ganzen Server gelten, muss das sozusagen im Kopf der Konfiguration geschehen. Bei kleineren Systemen ist das /etc/dhcp/dhcpd.conf, in meinem Beispiel mit einer gesplitteten Konfiguration werden diese Deklarationen in der /etc/dhcp/dhcp-server.conf eingefügt. Gezeigt ist hier die /etc/dhcp/dhcp-server.conf

# Interface des Servers 
subnet 172.16.199.0 netmask 255.255.255.0 { 
       } 

default-lease-time 3600; 
option domain-name "lab.digiliv.de"; 

# Options        
option vendor-encapsulated-options code 43 = string; 
option motorola-wlc code 191 = text;
option phone-provisioning code 66 = string;

Die Option 43 wird z.B. verwendet um Cisco APs an ihren Controller zu binden, genauso passiert das mit Motorola-APs über die Option 191.  Diese Optionen können nun in den Subnetzen mit Werten belegt werden, wie es bei den Cisco APs mit der Option 43 gezeigt wird.

Nebeneffekt: sind die Optionen global definiert, erscheinen sie in Webmin bei den Client-Optionen eines Subnets und können einfach mit Konfigurationswerten versehen werden.

DHCP-Optionen

Die DHCP-Optionen sind hier beschrieben: Dokumentation bei ISC

 

Option Number Name Beschreibung
2 Time Offset Time offset in seconds from UTC
3 Router N/4 router addresses
4 Time Servers N/4 time server addresses
5 Name Servers N/4 IEN-116 server addresses
6 DNS Servers N/4 DNS server addresses
7 Log Servers N/4 logging server addresses
8 Cookie Servers N/4 quote server addresses
9 LPR Servers N/4 printer server addresses
10 Impress Servers N/4 impress server addresses
11 RLP Servers N/4 RLP server addresses
12 Host Name Hostname string
13 Boot File Size Size of boot file in 512 byte chunks
14 Merit Dump File Client to dump and name of file to dump to
15 Domain Name The DNS domain name of the client
16 Swap Server Swap server addresses
17 Root Path Path name for root disk
18 Extension File Patch name for more BOOTP info
19 IP Layer Forwarding Enable or disable IP forwarding
20 Src route enabler Enable or disable source routing
21 Policy Filter Routing policy filters
22 Maximum DG Reassembly Size Maximum datagram reassembly size
23 Default IP TTL Default IP time-to-live
24 Path MTU Aging Timeout Path MTU aging timeout
25 MTU Plateau Path MTU plateau table
26 Interface MTU Size Interface MTU size
27 All Subnets Are Local All subnets are local
28 Broadcast Address Broadcast address
29 Perform Mask Discovery Perform mask discovery
30 Provide Mask to Others Provide mask to others
31 Perform Router Discovery Perform router discovery
32 Router Solicitation Address Router solicitation address
33 Static Routing Table Static routing table
34 Trailer Encapsulation Trailer encapsulation
35 ARP Cache Timeout ARP cache timeout
36 Ethernet Encapsulation Ethernet encapsulation
37 Default TCP Time to Live Default TCP time to live
38 TCP Keepalive Interval TCP keepalive interval
39 TCP Keepalive Garbage TCP keepalive garbage
40 NIS Domain Name NIS domain name
41 NIS Server Addresses NIS server addresses
42 NTP Servers Addresses NTP servers addresses
43 Vendor Specific Information Vendor specific information
44 NetBIOS Name Server NetBIOS name server
45 NetBIOS Datagram Distribution NetBIOS datagram distribution
46 NetBIOS Node Type NetBIOS node type
47 NetBIOS Scope NetBIOS scope
48 X Window Font Server X window font server
49 X Window Display Manager X window display manager
50 Requested IP address Requested IP address
51 IP Address Lease Time IP address lease time
52 Option Overload Overload “sname” or “file”
53 DHCP Message Type DHCP message type
54 DHCP Server Identification DHCP server identification
55 Parameter Request List Parameter request list
56 Message DHCP error message
57 DHCP Maximum Message Size DHCP maximum message size
58 Renew Time Value DHCP renewal (T1) time
59 Rebinding Time Value DHCP rebinding (T2) time
60 Client Identifier Client identifier
61 Client Identifier Client identifier
62 Netware/IP Domain Name Netware/IP domain name
63 Netware/IP sub Options Netware/IP sub options
64 NIS+ V3 Client Domain Name NIS+ V3 client domain name
65 NIS+ V3 Server Address NIS+ V3 server address
66 TFTP Server Name TFTP server name
67 Boot File Name Boot file name
68 Home Agent Addresses Home agent addresses
69 Simple Mail Server Addresses Simple mail server addresses
70 Post Office Server Addresses Post office server addresses
71 Network News Server Addresses Network news server addresses
72 WWW Server Addresses WWW server addresses
73 Finger Server Addresses Finger server addresses
74 Chat Server Addresses Chat server addresses
75 StreetTalk Server Addresses StreetTalk server addresses
76 StreetTalk Directory Assistance Addresses StreetTalk directory assistance addresses
77 User Class Information User class information
78 SLP Directory Agent Directory agent information
79 SLP Service Scope Service location agent scope
80 Rapid Commit Rapid commit
81 FQDN, Fully Qualified Domain Name Fully qualified domain name
82 Relay Agent Information Relay agent information
83 Internet Storage Name Service Internet storage name service
84 Undefined N/A
85 Novell Directory Servers Novell Directory Services servers
86 Novell Directory Server Tree Name Novell Directory Services server tree name
87 Novell Directory Server Context Novell Directory Services server context
88 BCMCS Controller Domain Name List CMCS controller domain name list
89 BCMCS Controller IPv4 Address List BCMCS controller IPv4 address list
90 Authentication Authentication
91 Undefined N/A
92 Undefined N/A
93 Client System Client system architecture
94 Client Network Device Interface Client network device interface
95 LDAP Use Lightweight Directory Access Protocol
96 Undefined N/A
97 UUID/GUID Based Client Identifier UUID/GUID-based client identifier
98 Open Group’s User Authentication Open group’s user authentication
99 Undefined N/A
100 Undefined N/A
101 Undefined N/A
102 Undefined N/A
103 Undefined N/A
104 Undefined N/A
105 Undefined N/A
106 Undefined N/A
107 Undefined N/A
108 Undefined N/A
109 Autonomous System Number Autonomous system number
110 Undefined  
111 Undefined  
112 NetInfo Parent Server Address NetInfo parent server address
113 NetInfo Parent Server Tag NetInfo parent server tag
114 URL: URL
115 Undefined N/A
116 Auto Configure DHCP auto-configuration
117 Name Service Search Name service search
118 Subnet Collection Subnet selection
119 DNS Domain Search List DNS domain search list
120 SIP Servers DHCP Option SIP servers DHCP option
121 Classless Static Route Option Classless static route option
122 CCC, CableLabs Client Configuration CableLabs client configuration
123 GeoConf GeoConf
124 Vendor-Identifying Vendor Class Vendor-identifying vendor class
125 Vendor Identifying Vendor Specific Vendor-identifying vendor specific
126 Undefined N/A
127 Undefined N/A
128 TFTP Server IP Address TFTP server IP address for IP phone software load
129 Call Server IP Address Call server IP address
130 Discrimination String Discrimination string to identify vendor
131 Remote Statistics Server IP Address Remote statistics server IP address
132 802.1Q VLAN ID IEEE 802.1Q VLAN ID
133 802.1Q L2 Priority IEEE 802.1Q layer 2 priority
134 Diffserv Code Point Diffserv code point for VoIP signalling and media streams
135 HTTP Proxy For Phone Applications HTTP proxy for phone-specific applications
136 Undefined N/A
137 Undefined N/A
138 Undefined N/A
139 Undefined N/A
140 Undefined N/A
141 Undefined N/A
142 Undefined N/A
143 Undefined N/A
144 Undefined N/A
145 Undefined N/A
146 Undefined N/A
147 Undefined N/A
148 Undefined N/A
149 Undefined N/A
150 TFTP Server Address, Etherboot, GRUB Config TFTP server address, Etherboot, GRUB configuration
151 Undefined  
152 Undefined N/A
153 Undefined N/A
154 Undefined N/A
155 Undefined N/A
156 Undefined N/A
157 Undefined N/A
158 Undefined N/A
159 Undefined N/A
160 Undefined N/A
161 Undefined N/A
162 Undefined N/A
163 Undefined N/A
164 Undefined N/A
165 Undefined N/A
166 Undefined N/A
167 Undefined N/A
168 Undefined N/A
169 Undefined N/A
170 Undefined N/A
171 Undefined N/A
172 Undefined N/A
173 Undefined N/A
174 Undefined N/A
175 Ether Boot Ether Boot
176 IP Telephone IP telephone
177 Ether Boot PacketCable and CableHome Ether Boot PacketCable and CableHome
178 Undefined N/A
179 Undefined N/A
180 Undefined N/A
181 Undefined N/A
182 Undefined N/A
183 Undefined N/A
184 Undefined N/A
185 Undefined N/A
186 Undefined N/A
187 Undefined N/A
188 Undefined N/A
189 Undefined N/A
190 Undefined N/A
191 Undefined N/A
192 Undefined N/A
193 Undefined N/A
194 Undefined N/A
195 Undefined N/A
196 Undefined N/A
197 Undefined N/A
198 Undefined N/A
199 Undefined N/A
200 Undefined N/A
201 Undefined N/A
202 Undefined N/A
203 Undefined N/A
204 Undefined N/A
205 Undefined N/A
206 Undefined N/A
207 Undefined N/A
208 pxelinux.magic (string) = 241.0.116.126 pxelinux.magic (string) = 241.0.116.126
209 pxelinux.configfile (text) pxelinux.configfile (text)
210 pxelinux.pathprefix (text) pxelinux.pathprefix (text)
211 pxelinux.reboottime pxelinux.reboottime
212 Undefined N/A
213 Undefined N/A
214 Undefined N/A
215 Undefined N/A
216 Undefined N/A
217 Undefined N/A
218 Undefined N/A
219 Undefined N/A
220 Subnet Allocation Subnet allocation
221 Virtual Subnet Allocation Virtual subnet selection
222 Undefined N/A
223 Undefined N/A
224 Private Use Private use
225 Private Use Private use
226 Private Use Private use
227 Private Use Private use
228 Private Use Private use
229 Private Use Private use
230 Private Use Private use
231 Private Use Private use
232 Private Use Private use
233 Private Use Private use
234 Private Use Private use
235 Private Use Private use
236 Private Use Private use
237 Private Use Private use
238 Private Use Private use
239 Private Use Private use
240 Private Use Private use
241 Private Use Private use
242 Private Use Private use
243 Private Use Private use
244 Private Use Private use
245 Private Use Private use
246 Private Use Private use
247 Private Use Private use
248 Private Use Private use
249 Private Use Private use
250 Private Use Private use
251 Private Use Private use
252 Private Use Private use
253 Private Use Private use
254 Private Use Private use
Category: Dienste, Netzwerk | Tag: , , ,