1.62.189.215 1.62.189.222
4.0.25.146 4.0.25.148
4.0.26.14 4.0.29.24
24.149.30.0 24.149.30.4

function range2cidr(ipStart, ipEnd, result, bits, mask, newip) {
    bits = 1
    mask = 1
    while (bits < 32) {
        newip = or(ipStart, mask)
        if ((newip>ipEnd) || ((lshift(rshift(ipStart,bits),bits)) != ipStart)) {
           bits--
           mask = rshift(mask,1)
           break
        }
        bits++
        mask = lshift(mask,1)+1
    }
    newip = or(ipStart, mask)
    bits = 32 - bits
    result = (result)?result ORS dec2ip(ipStart) "/" bits : dec2ip(ipStart) "/" bits
    if (newip < ipEnd) result = range2cidr(newip + 1, ipEnd,result)
    return result
}

# convert dotted quads to long decimal ip
#       int ip2dec("192.168.0.15")
#
function ip2dec(ip, slice) {
        split(ip, slice, ".")
        return (slice[1] * 2^24) + (slice[2] * 2^16) + (slice[3] * 2^8) + slice[4]
}

# convert decimal long ip to dotted quads
#       str dec2ip(1171259392)
#
function dec2ip(dec, ip, quad) {
        for (i=3; i>=1; i--) {
                quad = 256^i
                ip = ip int(dec/quad) "."
                dec = dec%quad
        }
        return ip dec
}

function sanitize(ip) {
        split(ip, slice, ".")
        return slice[1]/1 "." slice[2]/1 "." slice[3]/1 "." slice[4]/1
}

BEGIN{
        #FS=" |-|:"
        # to match BOTH formats: 'ip ip' AND the one in ydxerpxkpcfqjaybcssw file
        FS="[- :]"

}

# sanitize ip's
!/^#/ && NF {
  f1= sanitize($(NF-1))
  f2= sanitize($NF)
  cidr=range2cidr(ip2dec(f1), ip2dec(f2))
  if (pretty) {
     gsub("^|"ORS, ORS "\t", cidr)
     print  f1 " -> " f2 " : " cidr
  }
  else
     print cidr
}

END {print ""}

222.104.193.5 -> 222.104.193.5 :
        222.104.193.5/32
222.106.31.112 -> 222.106.31.112 :
        222.106.31.112/32
222.106.31.123 -> 222.106.31.123 :
        222.106.31.123/32
222.126.13.224 -> 222.126.13.231 :
        222.126.13.224/29
222.191.251.186 -> 222.191.251.186 :
        222.191.251.186/32
222.126.13.224 -> 222.126.13.251 :
        222.126.13.224/28
        222.126.13.240/29
        222.126.13.248/30
1.62.189.215 -> 1.62.189.222 :
        1.62.189.215/32
        1.62.189.216/30
        1.62.189.220/31
        1.62.189.222/32
4.0.25.146 -> 4.0.25.148 :
        4.0.25.146/31
        4.0.25.148/32
4.0.26.14 -> 4.0.29.24 :
        4.0.26.14/31
        4.0.26.16/28
        4.0.26.32/27
        4.0.26.64/26
        4.0.26.128/25
        4.0.27.0/24
        4.0.28.0/24
        4.0.29.0/28
        4.0.29.16/29
        4.0.29.24/32
24.149.30.0 -> 24.149.30.4 :
        24.149.30.0/30
        24.149.30.4/32

222.104.193.5 222.104.193.5
222.106.31.112 222.106.31.112
222.106.31.123 222.106.31.123
222.126.13.224 222.126.13.231
222.191.251.186 222.191.251.186
222.126.13.224 222.126.13.251
1.62.189.215 1.62.189.222
4.0.25.146 4.0.25.148
4.0.26.14 4.0.29.24
24.149.30.0 24.149.30.4