IP CIDR calculator

  • IP Multicast address ranges

    All multicast addresses can easily be recognized because they start with the bit pattern “1110”. - Well-known multicast addresses, control channels - Globally-scoped (Internet-wide) multicast addresses - Local multicast addresses

    Special and private address ranges

    Private address ranges are not routed on the Internet and can be freely allocated in any private network. NAT (network address translation) is required when connecting such a network to the Internet.

    Private network addresses (RFC1597/RFC1918 addresses): - A 24-bit block, /8, class A network - A 20-bit block, /12, set of 16 contiguous class B network numbers - A 16-bit block, /16, set of 255 contiguous class C network numbers

    Special addresses: - Special address range for the localhost. You can normally not use those addresses for anything else. is generally assigned to the loopback device _Special host address commonly reserved for the default route _

    Overview of common subnets and masks

    Mask Hosts  Usable Netmask          Hex Mask
    /30  4      2  fffffffc  this is 1/64 of a Class C net
    /29  8      6  fffffff8  this is 1/32 of a Class C net
    /28  16     14  fffffff0  this is 1/16 of a Class C net
    /27  32     30  ffffffe0  this is 1/8 of a Class C net
    /26  64     62  ffffffc0  this is 1/4 of a Class C net
    /24  256    254    ffffff00  this is a Class C net
    /23  512    510    fffffe00  these are 2 Class C net
    /22  1024   1022    fffffc00  these are 4 Class C net
    /21  2048   2046    fffff800  these are 8 Class C net
    /20  4096   4094    fffff000  these are 16 Class C net
    /19  8192   8190    ffffe000  these are 32 Class C net
    /18  16384  16382    ffffc000  these are 64 Class C net
    /17  32768  32766    ffff8000  these are 128 Class C net
    /16  65536  65534      ffff0000  these are 256 Class C net = Class B net

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Tmux Commands

screen and tmux

A comparison of the features (or more-so just a table of notes for accessing some of those features) for GNU screen and BSD-licensed tmux.

The formatting here is simple enough to understand (I would hope). ^ means ctrl+, so ^x is ctrl+x. M- means meta (generally left-alt or escape)+, so M-x is left-alt+x

It should be noted that this is no where near a full feature-set of either group. This - being a cheat-sheet - is just to point out the most very basic features to get you on the road.

Trust the developers and manpage writers more than me. This document is originally from 2009 when tmux was still new - since then both of these programs have had many updates and features added (not all of which have been dutifully noted here).

Action tmux screen
start a new session tmux OR
tmux new OR
tmux new-session
re-attach a detached session tmux attach OR
tmux attach-session
re-attach an attached session (detaching it from elsewhere) tmux attach -d OR
tmux attach-session -d
screen -dr
re-attach an attached session (keeping it attached elsewhere) tmux attach OR
tmux attach-session
screen -x
detach from currently attached session ^b d OR
^b :detach
^a ^d OR
^a :detach
rename-window to newname ^b , <newname> OR
^b :rename-window <newn>
^a A <newname>
list windows ^b w ^a w
list windows in chooseable menu ^a "
go to window # ^b # ^a #
go to last-active window ^b l ^a ^a
go to next window ^b n ^a n
go to previous window ^b p ^a p
see keybindings ^b ? ^a ?
list sessions ^b s OR
tmux ls OR
tmux list-sessions
screen -ls
toggle visual bell ^a ^g
create another window ^b c ^a c
exit current shell/window ^d ^d
split window/pane horizontally ^b " ^a S
split window/pane vertically ^b % ^a |
switch to other pane ^b o ^a <tab>
kill the current pane ^b x OR (logout/^D)
collapse the current pane/split (but leave processes running) ^a X
cycle location of panes ^b ^o
swap current pane with previous ^b {
swap current pane with next ^b }
show time ^b t
show numeric values of panes ^b q
toggle zoom-state of current pane (maximize/return current pane) ^b z
break the current pane out of its window (to form new window) ^b !
re-arrange current panels within same window (different layouts) ^b [space]
Kill the current window (and all panes within) ^b killw [target-window]
  • FYI for FreeBSD the driver only supports block size chunks, therefore:

    dd if=/dev/cd0 of=/name-the.iso bs=2048

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