1Whatmask(1) Network Whatmask(1)
2
6 whatmask - Subnet mask notation conversion tool.
7
9 whatmask <netmask or ip/netmask>
10 see the Examples section below
11
13 Whatmask is a small C program that will help you with network settings.
14 Whatmask can work in two modes. The first mode is to invoke Whatmask
16 with only a subnet mask as the argument. In this mode Whatmask will
17 echo back the subnet mask in four formats, plus the number of useable
18 addresses in the range.
19 Netmask Notations supported:
21 Name Example
22 CIDR /24
24 Netmask 255.255.255.0
25 Netmask (hex) 0xffffff00
26 Wilcard Bits 0.0.0.255
27 The above notations are all identical. CIDR notation commonly has a
29 "/" in front of the number (representing the number of bits). Whatmask
30 can accept these notations with or without a slash. This notation is
31 used more and more recently. A lot of popular routers and software sup‐
32 port this notation.
33 Netmask notation is pretty much the standard old-school way of doing
35 it. It is supported by most systems (Un*x, Win, Mac, etc.).
36 Netmask (Hex) is the hexadecimal representation of the netmask. Many
38 implementations of ifconfig use this notation
39 Wilcard Bits are similar to the netmask, but they are the logical not
41 of the netmask. This notation is used by a number of popular routers
42 (and nobody knows why...).
43 To use Whatmask in the first mode simply type "whatmask <notation>" The
45 notation can be in any of the four formats and Whatmask will automagi‐
46 cally figure out what it is and display all four notations.
47 To use Whatmask in its second mode execute Whatmask with any ip address
49 within the subnet, followed by a slash ('/'), followed by the subnet
50 mask in any format. (e.g. 192.168.0.23/255.255.255.224, or
51 192.168.0.23/27) Put no spaces in the argument.
52 Whatmask will echo back the following:
54 - The netmask in the following formats: CIDR, Netmask, Netmask (Hex),
57 Wildcard Bits
58 - The Network Address
60 - The Broadcast Address
62 - The number of Usable IP Addresses
64 - The First Usable IP Address
66 - The Last Usable IP Address
68 (Whatmask assumes that the Broadcast address is the highest
70 address in the subnet. This is the most common configuration.)
71
73 <no options> see above and below for usage.
74
76 Examples of how Whatmask works:
77 myhost> whatmask /26
79 ---------------------------------------------
81 TCP/IP SUBNET MASK EQUIVALENTS
82 ---------------------------------------------
83 CIDR = .....................: /26
84 Netmask = ..................: 255.255.255.192
85 Netmask (hex) = ............: 0xffffffc0
86 Wildcard Bits = ............: 0.0.0.63
87 Usable IP Addresses = ......: 62
88 myhost> whatmask 255.255.192.0
90 ---------------------------------------------
92 TCP/IP SUBNET MASK EQUIVALENTS
93 ---------------------------------------------
94 CIDR = .....................: /18
95 Netmask = ..................: 255.255.192.0
96 Netmask (hex) = ............: 0xffffc000
97 Wildcard Bits = ............: 0.0.63.255
98 Usable IP Addresses = ......: 16,382
99 myhost> whatmask 0xffffffe0
101 ---------------------------------------------
103 TCP/IP SUBNET MASK EQUIVALENTS
104 ---------------------------------------------
105 CIDR = .....................: /27
106 Netmask = ..................: 255.255.255.224
107 Netmask (hex) = ............: 0xffffffe0
108 Wildcard Bits = ............: 0.0.0.31
109 Usable IP Addresses = ......: 30
110 myhost> whatmask 0.0.0.31
112 ---------------------------------------------
114 TCP/IP SUBNET MASK EQUIVALENTS
115 ---------------------------------------------
116 CIDR = .....................: /27
117 Netmask = ..................: 255.255.255.224
118 Netmask (hex) = ............: 0xffffffe0
119 Wildcard Bits = ............: 0.0.0.31
120 Usable IP Addresses = ......: 30
121 myhost> whatmask 192.168.165.23/19
123 ------------------------------------------------
125 TCP/IP NETWORK INFORMATION
126 ------------------------------------------------
127 IP Entered = ..................: 192.168.165.23
128 CIDR = ........................: /19
129 Netmask = .....................: 255.255.224.0
130 Netmask (hex) = ...............: 0xffffe000
131 Wildcard Bits = ...............: 0.0.31.255
132 ------------------------------------------------
133 Network Address = .............: 192.168.160.0
134 Broadcast Address = ...........: 192.168.191.255
135 Usable IP Addresses = .........: 8,190
136 First Usable IP Address = .....: 192.168.160.1
137 Last Usable IP Address = ......: 192.168.191.254
138 myhost> whatmask 192.168.0.13/255.255.255.0
140 ------------------------------------------------
142 TCP/IP NETWORK INFORMATION
143 ------------------------------------------------
144 IP Entered = ..................: 192.168.0.13
145 CIDR = ........................: /24
146 Netmask = .....................: 255.255.255.0
147 Netmask (hex) = ...............: 0xffffff00
148 Wildcard Bits = ...............: 0.0.0.255
149 ------------------------------------------------
150 Network Address = .............: 192.168.0.0
151 Broadcast Address = ...........: 192.168.0.255
152 Usable IP Addresses = .........: 254
153 First Usable IP Address = .....: 192.168.0.1
154 Last Usable IP Address = ......: 192.168.0.254
155 myhost> whatmask 192.168.0.113/0xffffffe0
157 ------------------------------------------------
159 TCP/IP NETWORK INFORMATION
160 ------------------------------------------------
161 IP Entered = ..................: 192.168.0.113
162 CIDR = ........................: /27
163 Netmask = .....................: 255.255.255.224
164 Netmask (hex) = ...............: 0xffffffe0
165 Wildcard Bits = ...............: 0.0.0.31
166 ------------------------------------------------
167 Network Address = .............: 192.168.0.96
168 Broadcast Address = ...........: 192.168.0.127
169 Usable IP Addresses = .........: 30
170 First Usable IP Address = .....: 192.168.0.97
171 Last Usable IP Address = ......: 192.168.0.126
172 myhost> whatmask 192.168.0.169/0.0.0.127
174 ------------------------------------------------
176 TCP/IP NETWORK INFORMATION
177 ------------------------------------------------
178 IP Entered = ..................: 192.168.0.169
179 CIDR = ........................: /25
180 Netmask = .....................: 255.255.255.128
181 Netmask (hex) = ...............: 0xffffff80
182 Wildcard Bits = ...............: 0.0.0.127
183 ------------------------------------------------
184 Network Address = .............: 192.168.0.128
185 Broadcast Address = ...........: 192.168.0.255
186 Usable IP Addresses = .........: 126
187 First Usable IP Address = .....: 192.168.0.129
188 Last Usable IP Address = ......: 192.168.0.254
189
192 Report bugs to <software@laffeycomputer.com>
193
196 Original code:
197 Joe Laffey <software@laffeycomputer.com>
198 Assistance with Manpage and Packaging:
200 David Wirch <kuma@linuxboxen.org>
201 Many thanks to the beta testers and users who sent in valuable feed‐
203 back!
204
207 Official Whatmask website:
208 http://www.laffeycomputer.com/whatmask.html
209LAFFEY Computer Imaging Nov 14, 2003 Whatmask(1)