Difference between revisions of "Netmask"
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So the network the netmask indicates is 192.168.0.0/24. Netmasks are often written in [[CIDR]] notation, in IPv4 and almost exclusively in [[IPv6]]. A /64 which is common in delegation in IPv6 holds an immense amount of data, yet it would be wrong to write it as FFFF:FFFF:FFFF:FFFF::, at least it seems wrong. | So the network the netmask indicates is 192.168.0.0/24. Netmasks are often written in [[CIDR]] notation, in IPv4 and almost exclusively in [[IPv6]]. A /64 which is common in delegation in IPv6 holds an immense amount of data, yet it would be wrong to write it as FFFF:FFFF:FFFF:FFFF::, at least it seems wrong. | ||
+ | |||
+ | In [[UBO]]'s the netmask is displayed by the ifconfig command: | ||
+ | |||
+ | In BSD: | ||
+ | margaret$ ifconfig vic0 | ||
+ | vic0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 | ||
+ | lladdr 00:0c:29:9e:6b:a6 | ||
+ | groups: egress | ||
+ | media: Ethernet autoselect | ||
+ | status: active | ||
+ | inet6 fe80::20c:29ff:fe9e:6ba6%vic0 prefixlen 64 scopeid 0x1 | ||
+ | inet 192.168.0.27 netmask 0xffffff00 broadcast 192.168.0.255 | ||
+ | inet6 2001:a60:f074::2 prefixlen 48 | ||
+ | |||
+ | In Linux: | ||
+ | |||
+ | [pjp@uranus ~]$ ifconfig eth1 | ||
+ | eth1 Link encap:Ethernet HWaddr 00:01:03:DE:BE:6E | ||
+ | inet addr:192.168.0.1 Bcast:192.168.0.255 Mask:255.255.255.0 | ||
+ | inet6 addr: 2001:a60:f074::1/48 Scope:Global | ||
+ | inet6 addr: fe80::201:3ff:fede:be6e/64 Scope:Link | ||
+ | UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 |
Latest revision as of 08:43, 29 April 2009
A Netmask masks the bits of your network for a particular IP. A netmask is a continuous stream of binary 1's from 0 through 32 bits. Here is a few common netmasks
IP: 192.168.0.1 NM: 255.255.255.0
So the network the netmask indicates is 192.168.0.0/24. Netmasks are often written in CIDR notation, in IPv4 and almost exclusively in IPv6. A /64 which is common in delegation in IPv6 holds an immense amount of data, yet it would be wrong to write it as FFFF:FFFF:FFFF:FFFF::, at least it seems wrong.
In UBO's the netmask is displayed by the ifconfig command:
In BSD:
margaret$ ifconfig vic0 vic0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 lladdr 00:0c:29:9e:6b:a6 groups: egress media: Ethernet autoselect status: active inet6 fe80::20c:29ff:fe9e:6ba6%vic0 prefixlen 64 scopeid 0x1 inet 192.168.0.27 netmask 0xffffff00 broadcast 192.168.0.255 inet6 2001:a60:f074::2 prefixlen 48
In Linux:
[pjp@uranus ~]$ ifconfig eth1 eth1 Link encap:Ethernet HWaddr 00:01:03:DE:BE:6E inet addr:192.168.0.1 Bcast:192.168.0.255 Mask:255.255.255.0 inet6 addr: 2001:a60:f074::1/48 Scope:Global inet6 addr: fe80::201:3ff:fede:be6e/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1