cidr ip block

This is very useful if you can't remember netmask or how much IP's are usable and belongs IP block.

IP/CIDR Δ to last IP addr Mask Hosts (*) Size Notes
a.b.c.d/32 +0.0.0.0 255.255.255.255 1 1/256 C
a.b.c.d/31 +0.0.0.1 255.255.255.254 2 1/128 C d = 0 … (2n) … 254
a.b.c.d/30 +0.0.0.3 255.255.255.252 4 1/64 C d = 0 … (4n) … 252
a.b.c.d/29 +0.0.0.7 255.255.255.248 8 1/32 C d = 0 … (8n) … 248
a.b.c.d/28 +0.0.0.15 255.255.255.240 16 1/16 C d = 0 … (16n) … 240
a.b.c.d/27 +0.0.0.31 255.255.255.224 32 ⅛ C d = 0 … (32n) … 224
a.b.c.d/26 +0.0.0.63 255.255.255.192 64 ¼ C d = 0, 64, 128, 192
a.b.c.d/25 +0.0.0.127 255.255.255.128 128 ½ C d = 0, 128
a.b.c.0/24 +0.0.0.255 255.255.255.000 256 1 C
a.b.c.0/23 +0.0.1.255 255.255.254.000 512 2 C c = 0 … (2n) … 254
a.b.c.0/22 +0.0.3.255 255.255.252.000 1,024 4 C c = 0 … (4n) … 252
a.b.c.0/21 +0.0.7.255 255.255.248.000 2,048 8 C c = 0 … (8n) … 248
a.b.c.0/20 +0.0.15.255 255.255.240.000 4,096 16 C c = 0 … (16n) … 240
a.b.c.0/19 +0.0.31.255 255.255.224.000 8,192 32 C c = 0 … (32n) … 224
a.b.c.0/18 +0.0.63.255 255.255.192.000 16,384 64 C c = 0, 64, 128, 192
a.b.c.0/17 +0.0.127.255 255.255.128.000 32,768 128 C c = 0, 128
a.b.0.0/16 +0.0.255.255 255.255.000.000 65,536 256 C = 1 B
a.b.0.0/15 +0.1.255.255 255.254.000.000 131,072 2 B b = 0 … (2n) … 254
a.b.0.0/14 +0.3.255.255 255.252.000.000 262,144 4 B b = 0 … (4n) … 252
a.b.0.0/13 +0.7.255.255 255.248.000.000 524,288 8 B b = 0 … (8n) … 248
a.b.0.0/12 +0.15.255.255 255.240.000.000 1,048,576 16 B b = 0 … (16n) … 240
a.b.0.0/11 +0.31.255.255 255.224.000.000 2,097,152 32 B b = 0 … (32n) … 224
a.b.0.0/10 +0.63.255.255 255.192.000.000 4,194,304 64 B b = 0, 64, 128, 192
a.b.0.0/9 +0.127.255.255 255.128.000.000 8,388,608 128 B b = 0, 128
a.0.0.0/8 +0.255.255.255 255.000.000.000 16,777,216 256 B = 1 A
a.0.0.0/7 +1.255.255.255 254.000.000.000 33,554,432 2 A a = 0 … (2n) … 254
a.0.0.0/6 +3.255.255.255 252.000.000.000 67,108,864 4 A a = 0 … (4n) … 252
a.0.0.0/5 +7.255.255.255 248.000.000.000 134,217,728 8 A a = 0 … (8n) … 248
a.0.0.0/4 +15.255.255.255 240.000.000.000 268,435,456 16 A a = 0 … (16n) … 240
a.0.0.0/3 +31.255.255.255 224.000.000.000 536,870,912 32 A a = 0 … (32n) … 224
a.0.0.0/2 +63.255.255.255 192.000.000.000 1,073,741,824 64 A a = 0, 64, 128, 192
a.0.0.0/1 +127.255.255.255 128.000.000.000 2,147,483,648 128 A a = 0, 128
0.0.0.0/0 +255.255.255.255 000.000.000.000 4,294,967,296 256 A
Also please look there:


Netmask              Netmask (binary)                 CIDR     Notes    
_____________________________________________________________________________
255.255.255.255  11111111.11111111.11111111.11111111  /32  Host (single addr)
255.255.255.254  11111111.11111111.11111111.11111110  /31  Unuseable
255.255.255.252  11111111.11111111.11111111.11111100  /30    2  useable
255.255.255.248  11111111.11111111.11111111.11111000  /29    6  useable
255.255.255.240  11111111.11111111.11111111.11110000  /28   14  useable
255.255.255.224  11111111.11111111.11111111.11100000  /27   30  useable
255.255.255.192  11111111.11111111.11111111.11000000  /26   62  useable
255.255.255.128  11111111.11111111.11111111.10000000  /25  126  useable
255.255.255.0    11111111.11111111.11111111.00000000  /24 "Class C" 254 useable

255.255.254.0    11111111.11111111.11111110.00000000  /23    2  Class C's
255.255.252.0    11111111.11111111.11111100.00000000  /22    4  Class C's
255.255.248.0    11111111.11111111.11111000.00000000  /21    8  Class C's
255.255.240.0    11111111.11111111.11110000.00000000  /20   16  Class C's
255.255.224.0    11111111.11111111.11100000.00000000  /19   32  Class C's
255.255.192.0    11111111.11111111.11000000.00000000  /18   64  Class C's
255.255.128.0    11111111.11111111.10000000.00000000  /17  128  Class C's
255.255.0.0      11111111.11111111.00000000.00000000  /16  "Class B"

255.254.0.0      11111111.11111110.00000000.00000000  /15    2  Class B's
255.252.0.0      11111111.11111100.00000000.00000000  /14    4  Class B's
255.248.0.0      11111111.11111000.00000000.00000000  /13    8  Class B's
255.240.0.0      11111111.11110000.00000000.00000000  /12   16  Class B's
255.224.0.0      11111111.11100000.00000000.00000000  /11   32  Class B's
255.192.0.0      11111111.11000000.00000000.00000000  /10   64  Class B's
255.128.0.0      11111111.10000000.00000000.00000000  /9   128  Class B's
255.0.0.0        11111111.00000000.00000000.00000000  /8   "Class A"

254.0.0.0        11111110.00000000.00000000.00000000  /7
252.0.0.0        11111100.00000000.00000000.00000000  /6
248.0.0.0        11111000.00000000.00000000.00000000  /5
240.0.0.0        11110000.00000000.00000000.00000000  /4
224.0.0.0        11100000.00000000.00000000.00000000  /3
192.0.0.0        11000000.00000000.00000000.00000000  /2
128.0.0.0        10000000.00000000.00000000.00000000  /1
0.0.0.0          00000000.00000000.00000000.00000000  /0   IP space

                                   Net     Host    Total
Net      Addr                      Addr    Addr    Number
Class   Range      NetMask         Bits    Bits   of hosts
----------------------------------------------------------
A        0-127    255.0.0.0         8      24     16777216   (i.e. 114.0.0.0)
B      128-191    255.255.0.0      16      16        65536   (i.e. 150.0.0.0)
C      192-254    255.255.255.0    24       8          256   (i.e. 199.0.0.0)
D      224-239    (multicast)
E      240-255    (reserved)
F      208-215    255.255.255.240  28       4           16
G      216/8      ARIN - North America
G      217/8      RIPE NCC - Europe
G      218-219/8  APNIC
H      220-221    255.255.255.248  29       3            8   (reserved)
K      222-223    255.255.255.254  31       1            2   (reserved)
(ref: RFC1375 & http://www.iana.org/assignments/ipv4-address-space )
(               http://www.iana.org/numbers.htm                    )
----------------------------------------------------------

The current list of special use prefixes:
	0.0.0.0/8	
	127.0.0.0/8
	192.0.2.0/24
	10.0.0.0/8
	172.16.0.0/12
	192.168.0.0/16
	169.254.0.0/16
	all D/E space
(ref: RFC1918 http://www.rfc-editor.org/rfc/rfc1918.txt   )
(       or     ftp://ftp.isi.edu/in-notes/rfc1918.txt     )
(rfc search:   http://www.rfc-editor.org/rfcsearch.html   )
(              http://www.ietf.org/ietf/1id-abstracts.txt )
(              http://www.ietf.org/shadow.html            )

Martians: (updates at: www.iana.org/assignments/ipv4-address-space )
 no ip source-route
 access-list 100 deny   ip host 0.0.0.0 any
  deny ip 0.0.0.0         0.255.255.255  any log  ! antispoof
  deny ip 0.0.0.0 0.255.255.255  0.0.0.0 255.255.255.255 ! antispoof
  deny ip any             255.255.255.128 0.0.0.127 ! antispoof
  deny ip host            0.0.0.0        any log  ! antispoof
  deny ip host            [router intf]  [router intf] ! antispoof
  deny ip xxx.xxx.xxx.0   0.0.0.255      any log  ! lan area
  deny ip 0/8             0.255.255.255  any log  ! IANA - Reserved
  deny ip 1/8             0.255.255.255  any log  ! IANA - Reserved
  deny ip 2/8             0.255.255.255  any log  ! IANA - Reserved
  deny ip 5/8             0.255.255.255  any log  ! IANA - Reserved
  deny ip 7/8             0.255.255.255  any log  ! IANA - Reserved
  deny ip 10.0.0.0        0.255.255.255  any log  ! IANA - Private Use
  deny ip 23/8            0.255.255.255  any log  ! IANA - Reserved
  deny ip 27/8            0.255.255.255  any log  ! IANA - Reserved
  deny ip 31/8            0.255.255.255  any log  ! IANA - Reserved
  deny ip 36-37/8         0.255.255.255  any log  ! IANA - Reserved
  deny ip 39/8            0.255.255.255  any log  ! IANA - Reserved
  deny ip 41-42/8         0.255.255.255  any log  ! IANA - Reserved
  deny ip 50/8            0.255.255.255  any log  ! IANA - Reserved
  deny ip 58-60/8         0.255.255.255  any log  ! IANA - Reserved
  deny ip 69-79/8         0.255.255.255  any log  ! IANA - Reserved
  deny ip 82-95/8         0.255.255.255  any log  ! IANA - Reserved
  deny ip 96-126/8        0.255.255.255  any log  ! IANA - Reserved
  deny ip 127/8           0.255.255.255  any log  ! IANA - Reserved
  deny ip 169.254.0.0     0.0.255.255    any log  ! link-local network
  deny ip 172.16.0.0      0.15.255.255   any log  ! reserved
  deny ip 192.168.0.0     0.0.255.255    any log  ! reserved
  deny ip 192.0.2.0       0.0.0.255      any log  ! test network
  deny ip 197/8           0.255.255.255  any log  ! IANA - Reserved
  deny ip 220/8           0.255.255.255  any log  ! IANA - Reserved
  deny ip 222-223/8       0.255.255.255  any log  ! IANA - Reserved
  deny ip 224.0.0.0       31.255.255.255 any log  ! multicast
  deny ip 224.0.0.0       15.255.255.255 any log  ! unless MBGP-learned routes
  deny ip 224-239/8       0.255.255.255  any log  ! IANA - Multicast
  deny ip 240-255/8       0.255.255.255  any log  ! IANA - Reserved

filtered source addresses
  0/8                 ! broadcast
  10/8                ! RFC 1918 private
  127/8               ! loopback
  169.254.0/16        ! link local
  172.16.0.0/12       ! RFC 1918 private
  192.0.2.0/24        ! TEST-NET
  192.168.0/16        ! RFC 1918 private
  224.0.0.0/4         ! class D multicast
  240.0.0.0/5         ! class E reserved
  248.0.0.0/5         ! reserved
  255.255.255.255/32  ! broadcast

ARIN administrated blocks: (http://www.arin.net/regserv/IPStats.html)
   24.0.0.0/8 (portions of)
   63.0.0.0/8
   64.0.0.0/8
   65.0.0.0/8
   66.0.0.0/8
  196.0.0.0/8
  198.0.0.0/8
  199.0.0.0/8
  200.0.0.0/8
  204.0.0.0/8
  205.0.0.0/8
  206.0.0.0/8
  207.0.0.0/8
  208.0.0.0/8
  209.0.0.0/8
  216.0.0.0/8
----------------------------------------------------------

well known ports: (rfc1700.txt)
 www.iana.org/assignments/port-numbers

protocol numbers:
 www.iana.org/assignments/protocol-numbers
 www.iana.org/numbers.htm

ICMP(Types/Codes)
 Testing Destination Reachability & Status
  (0/0)  Echo-Reply
  (8/0)  Echo
 Unreachable Destinations
  (3/0)  Network Unreachable
  (3/1)  Host Unreachable
  (3/2)  Protocol Unreachable
  (3/3)  Port Unreachable
  (3/4)  Fragmentaion Needed and DF set (Pkt too big)
  (3/5)  Source Route Failed
  (3/6)  Network Unknown
  (3/7)  Host Unknown
  (3/9)  DOD Net Prohibited
  (3/10) DOD Host Prohibited
  (3/11) Net TOS Unreachable
  (3/12) Host TOS Unreachable
  (3/13) Administratively Prohibited
  (3/14) Host Precedence Unreachable
  (3/15) Precedence Unreachable
 Flow Control
  (4/0)  Source-Quench [RFC 1016]
 Route Change Requests from Gateways
  (5/0)  Redirect Datagrams for the Net
  (5/1)  Redirect Datagrams for the Host
  (5/2)  Redirect Datagrams for the TOS and Net
  (5/3)  Redirect Datagrams for the TOS and Host
 Router
  (6/-)  Alternate-Address
  (9/0)  Router-Advertisement
  (10/0) Router-Solicitation
 Detecting Circular or Excessively Long Routes
  (11/0) Time to Live Count Exceeded
  (11/1) Fragment Reassembly Time Exceeded
 Reporting Incorrect Datagram Headers
  (12/0) Parameter-Problem
  (12/1) Option Missing
  (12/2) No Room for Option
 Clock Synchronization and Transit Time Estimation
  (13/0) Timestamp-Request
  (14/0) Timestamp-Reply
 Obtaining a Network Address (RARP Alternative)
  (15/0) Information-Request
  (16/0) Information-Reply
 Obtaining a Subnet Mask [RFC 950]
  (17/0) Address Mask-Request
  (18/0) Address Mask-Reply
 Other
  (30/0) Traceroute
  (31/0) Conversion-Error
  (32/0) Mobile-Redirect

Ref: [RFC 792] [RFC 896] [RFC 950] [RFC 1016]
  www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/sw_5_3/cofigide/qos.htm#19774

Decimal system Prefix's
              Factor               Exponent  Prefix
---------------------------------------------------
 1 000 000 000 000 000 000 000 000...10^24....yotta
     1 000 000 000 000 000 000 000...10^21....zetta
         1 000 000 000 000 000 000...10^18....exa
             1 000 000 000 000 000...10^15....peta
                 1 000 000 000 000...10^12....tera
                     1 000 000 000...10^9.....giga
                         1 000 000...10^6.....mega
                             1 000...10^3.....kilo
                               100...10^2.....hecto
                                10...10^1.....deka
                               0.1...10^-1....deci
                              0.01...10^-2....centi
                             0.001...10^-3....milli
                         0.000 001...10^-6....micro
                     0.000 000 001...10^-9....nano
                 0.000 000 000 001...10^-12...pico
             0.000 000 000 000 001...10^-15...femto
         0.000 000 000 000 000 001...10^-18...atto
     0.000 000 000 000 000 000 001...10^-21...zepto
 0.000 000 000 000 000 000 000 001...10^-24...yocto
---------------------------------------------------

Convert Fahrenheit <> Celsius:
 Celsius = (Fahrenheit - 32) / 1.8
 Fahrenheit = (Celsius * 1.8) + 32

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