for IPv4? Neat! and (slightly off topic): [root@oswego ~]# mount 2340401093:/tb /mnt/d1 [root@oswego ~]# ls !$ (correct listing) [root@oswego ~]# ssh 2340401093 The authenticity of host '2340401093 (139.127.175.197)' can't be established. RSA key fingerprint is 25:0a:b3:d8:9b:57:19:64:d3:8a:20:49:be:6a:78:17. Are you sure you want to continue connecting (yes/no)? yes Warning: Permanently added '2340401093,139.127.175.197' (RSA) to the list of known hosts. Last login: Thu Sep 18 15:52:54 2014 from oswego.upstate.edu
But my mozilla browser is overly helpful: doesn't look like an IP name or address, so add www. in front and .com after. That doesn't work! easier way to calculate: ((139*256+127)*256+175)*256+197 Shift left and add the next byte, 4 times On 09/17/2014 08:12 PM, Michael B. Smith wrote:
Yes, that is explicitly allowed and always has been for IPv4. *From:*[email protected] [mailto:[email protected]] *On Behalf Of *Crawford, Scott *Sent:* Wednesday, September 17, 2014 8:07 PM *To:* [email protected] *Subject:* [NTSysADM] RE: Pinging with less than 3 octets While we’re on the subject of ip address shortcuts, this is fairly interesting too: Get an IP: ping microsoft.com Pinging microsoft.com [134.170.188.221] with 32 bytes of data: Take each of the octets and convert them to binary: 134 = 10000110 170 = 10101010 188 = 10111100 221 = 11011101 Then, concatenate them into one long 32 bit string: 10000110 10101010 10111100 11011101 Convert that back into a single decimal number: 2259336413 And, ping it: ping 2259336413 Pinging 134.170.188.221 with 32 bytes of data: Or, try it in browser to get to Microsoft’s page: http://2259336413 *From:* [email protected] <mailto:[email protected]> [mailto:[email protected]] *On Behalf Of *Michael B. Smith *Sent:* Wednesday, September 17, 2014 4:43 PM *To:* [email protected] <mailto:[email protected]> *Subject:* [NTSysADM] RE: Pinging with less than 3 octets That was my initial guess… a parsing shortcut. But it appears to predate that, significantly. *From:*[email protected] <mailto:[email protected]> [mailto:[email protected]] *On Behalf Of *Crawford, Scott *Sent:* Wednesday, September 17, 2014 5:38 PM *To:* [email protected] <mailto:[email protected]> *Subject:* [NTSysADM] RE: Pinging with less than 3 octets Cool. Thanks for the info. I guess if its documented, it’ll prolly work for a while…at least til we’re all v6. J I wonder if it had similar origins to the IPv6 double-colon shortcut. *From:* [email protected] <mailto:[email protected]> [mailto:[email protected]] *On Behalf Of *Michael B. Smith *Sent:* Wednesday, September 17, 2014 4:15 PM *To:* [email protected] <mailto:[email protected]> *Subject:* [NTSysADM] RE: Pinging with less than 3 octets Very nice. The behavior is documented on Windows: http://msdn.microsoft.com/en-us/library/system.net.ipaddress.parse(v=vs.110).aspx It’s used for building “class-full” IP addresses. Which are obsolete. And it is also present in BSD-Unix and in Darwin. I sure as heck don’t remember it from my Unix days though. http://en.verysource.com/code/15332_1/inet_addr.c.html http://www.opensource.apple.com/source/Libinfo/Libinfo-330/dns.subproj/inet_addr.c *From:*[email protected] <mailto:[email protected]> [mailto:[email protected]] *On Behalf Of *Crawford, Scott *Sent:* Wednesday, September 17, 2014 4:19 PM *To:* [email protected] <mailto:[email protected]> *Subject:* [NTSysADM] Pinging with less than 3 octets When pinging, you can leave out the 3^rd octet and windows will pad the address to fill the missing 3^rd octet with 0. This also works if you leave out the 2^nd and 3^rd . Heck, it even works without the 1^st J I’ve noticed this for quite a while, but have never seen it discussed. Can anyone tell me why this works? Is it in a spec? Or, just an interesting anomaly? I use it as a shortcut pretty often and just never bothered to research it much. C:\>ping 10.1.1 Pinging 10.1.0.1 with 32 bytes of data: C:\>ping 10.1 Pinging 10.0.0.1 with 32 bytes of data: C:\>ping 10 Pinging 0.0.0.10 with 32 bytes of data:
