[rmax] - April 2005

This little tool takes a list of IPv4 addresses on the command line, and calculates the respective IPv6 address prefixes for the 6to4 network.

 package require Tcl

 # calculate the 6to4 prefix for a given IPv4 address
 proc 6to4 {addr} {
    set addr [split [string trim $addr] .]
    if {[llength $addr] != 4} {
	return -code error \
	    "\"$addr\" does not consist of 4 octets separated by dots"
    }
    foreach octet $addr {
	if {![string is integer $octet] || $octet < 0 || $octet > 255} {
	    return -code error "\"$octet\" is not a valid octet"
	}
    }
    eval [linsert $addr 0 format "2002:%x%02x:%x%02x::"]
 }

 foreach v4 $argv {
    catch {6to4 $v4} v6
    puts "$v4 -> $v6"
 }

----
[[ [Category Internet] ]]