I'm trying to following the Quick Start Wordpress for Google App Engine guide; however, the Google Cloud Console appears to have changed slightly with respect to the instructions.
One of the instructions is to select Assign IP Address, and add your IP address to the list of Authorized IP Addressed. The link points to a Google search for "what's my IP address". However, the result does not look like it is in CIDR notation as required:
The IP address doesn't have a slash in it as in the CIDR example. Would it be OK just to enter the "public IP address" as it appears in Google search in the Network field?
Update
I tried entering my public IP address, but it appears with the gray italic text "Not saved" (see below), which does not look promising.
Just add '/32' to your ip... so it should be
82.217.236.160/32
I used whois.geektools.com to look up the IP address you mentioned. If that's
your actual IP address, then the IP range assigned to your ISP is:
inetnum: 82.217.192.0 - 82.217.255.255
netname: ZIGGO-CM
If you convert those IP addresses into binary, then the first 18 bits are
constant for that block of addresses, and the other 14 bits could vary, depending on how your ISP dishes them out to their customers.
So 82.217.192.0/18 (your ISP's block of IP addresses, in CIDR notation) might be a more convenient choice than the 82.217.236.160/32 value, corresponding to the single IP address currently assigned to you at the moment.
Related
This is from my lecture slides in the web based systems section of Distributed Systems:
Which of the following hostnames are valid?
122.65.132.11.1.97
My_server
300.320.1.32
The answer is: All three can be valid depending on the scheme used.
I would have thought the answer would be that none are valid; can someone explain why all three could be valid?
First: the ip address is the actual name of the host. Everything else is DNS entry that maps to the ip address.
122.65.132.11.1.97 is a valid IPv6 ip address.
My_server is a valid DNS entry (which presumably could map to a legit host).
Corrected:
300.320.1.32 is a not a valid IPV4 ip address.
I'm studying subnetting and I can't seem to find a straight answer to what seems like a simple question. Say I have the network 192.168.1.0/26 or in other words, 192.168.1.0 - 192.168.1.63
I have 64 IP's in total and I know the last usable one is 192.168.1.62 since 192.168.1.63 is the broadcast address. Where is the first usable address and how do the Default Gateway, Loopback address and Network IP figure in? I keep getting conflicting info.
For any subnet, there is a "network address" and a "broadcast address". The former is the subnet prefix followed by all zero bits and the latter is the subnet prefix followed by all one bits.
Thus, an N-bit subnet has 2^N - 2 addresses available. (Where N=32-M in A.B.C.D/M notation.)
The "default gateway" is an address on any local subnet where is sent all traffic not destined for any local subnets. It can be any valid subnet address though it's common for it to be the very first address of the subnet on which in resides. A machine can be connected to many subnets (eth0, eth1, wifi0, etc.) but has only one default gateway.
The "loopback address" is not part of a subnet. It is its own interface and has the address 127.0.0.1/8 so any address starting with 127 will reference the local machine.
Note: I have seen configuration options to make the "broadcast address" match the "network address" but I've never seen this used in practice.
When analyzing network traffic in Wireshark, it would be helpful on occasion to look at a string variable representing an IP address instead of the actual IPv4/6 address.
In the IP source or destination column, instead of seeing 192.168.1.44, I would like to see "tom's laptop" or "smtp-server". Is this possible? Some type of IP-to-String aliasing?
I understand there is an option to enable name resolution for the Network Layer, this would translate a public IP into its registered domain name. Specifically when dealing with private IP addresses, this would not be helpful.
the application I am developing needs to support both IPv4 and IPv6 page. The application exposes a web page for user to configure the server details as follows. This is perfect for IPv4 address.
As the IPv6 address embeds the subnet within the IP Address itself, it's a bit confusing how to accept the subnet information.
I can take the following approaches
User has an IPv6 address which contains information including subnet mask. Let the user enters the whole stuffs on screen and we will disable IPv4 subnet mask text box.
User has an IPv6 address without the subnet information. we will allow user to enter the subnet information in the subnet textbox and later merge the information together to prepare the full IPv6 address.
The second method methods seems not elegant. In my understanding, simply taking ipconfig from the console, the IPv6 address it displays contains the subnet information as well. So that user can easily enter this information in the input page. What's the standard way of doing this?
The prefix length (subnet mask) is never part of the address. Just like you can write address+prefixlen as 192.0.2.0/24 in IPv4 you write 2001:db8:0:2::/64 in IPv6. Much easier than the old 255.255.255.0 subnet mask notation.
I would use the more convenient (CIDR) notation for both IPv4 and IPv6, and in one textbox. Much easier when copy&pasteing :-)
I read a book about IP & MAC addresses.
As I understand, we use ARP in order to find the MAC address of the PC.
My question is if there is only one MAC address for each IP's address? And if so, why do we need the IP address? Why we can't easily go to the MAC address?
There should only be one MAC address per IP address but the MAC address never leaves the subnet and the MAC address has nothing to do with routing outside the subnet. You can't say anything about where a packet should go from outside the subnet given only MAC address. Think of it like a person's name. Even if it were unique it wouldn't help you find them. You need to look up the street address (ARP) and use a map (routing table) to figure out how to get there. Then once you get to the right house (subnet) you just dump all the mail on the counter and let everyone pick up the mail with their name (MAC address) on it.