7 votes
Accepted

Does 0.0.0.0/7 represent the same range as 1.0.0.0/8?

Clearly these are not the same. However, nothing in 0.0.0.0/8 is a valid destination address, so the effect of each route would be the same. Attempts to connect to anything in 0.0.0.0/8 would just ...
Michael Hampton's user avatar
7 votes
Accepted

Is it possible to change CIDR network flannel and Kubernetes

I've managed to change Flannel CIDR network pool in the following way: Assuming that you have installed a fresh k8s cluster via kubeadm builder tool with adopting appropriate --pod-network-cidr flag ...
Nick_Kh's user avatar
  • 578
7 votes

What does the netmask in an IP address actually tell you?

how does the netmask let us distinguish two IP addresses? It doesn't. I lets us or a device distinguish the scope of the network to which it is attached. I don't see how these are two different ...
YLearn's user avatar
  • 1,247
6 votes

What does the netmask in an IP address actually tell you?

The network mask is not part of the address. It defines how big your neighborhood is, as in Mikhail Khirgiy's example. With a /8 mask, Bob knows everyone in New York personally. He can hand-deliver ...
Charles Burge's user avatar
5 votes
Accepted

What is a correct IP4 CIDR for AWS?

You need to create subnet, which is in range 10.0.0.0/16 . For example: 10.0.0.0/24 10.2.0.128/25 etc
batistuta09's user avatar
  • 9,106
4 votes
Accepted

Why is my AWS instance's private IP outside of the subnet's range?

The aws_instance resource in the example does not have the subnet_id attribute provided, so the instance would launch into your account's default subnet for the target region. It's likely that the ...
Martin Atkins's user avatar
4 votes

What does the netmask in an IP address actually tell you?

The netmask tells the device how to contact other IP addresses. Anything in the same network, as defined by the netmask, is contacted directly; anything outside the same network has to be contacted ...
Mike Scott's user avatar
  • 8,053
4 votes
Accepted

What IP addresses are included in a subnet "range"?

The subnet mask is a bit mask. The appended /30 means the netmask spans the highest 30 bits (out of 32 bits): 12 . 245 . 105 . 190 IPv4 address decimal 0000 1100 . 1111 0101 ....
Olaf Dietsche's user avatar
4 votes
Accepted

What if my public address is same as one of the IP address in my AWS VPC CIDR Block?

That 112.110.x.x belongs to Idea Cellular Ltd, you shouldn’t use it in your VPC. Instead choose one of the reserved “private IP ranges” (RFC1918): 10.0.0.0/16, 172.16.0.0/12 or 192.168.0.0/16 Having ...
MLu's user avatar
  • 25.4k
4 votes

What is a correct IP4 CIDR for AWS?

TL;DR version (Amazon VPC FAQs) Read about CIDR Notation to understand what the below means. AWS VPC CIDR block size must be between /16 and /28, e.g. 192.168.0.0/16 Subnet CIDR block sizes must also ...
MLu's user avatar
  • 25.4k
4 votes
Accepted

What does a CIDR mask mean in the context of "ip address add"?

ip address add dev wg0 192.168.2.1/24 That adds the IP address 192.168.2.1 to the indicated interface, with a subnet mask of /24 or 255.255.255.0. The possible IP addresses for wg clients are 192.168....
Zac67's user avatar
  • 11.5k
3 votes

Subnet CIDR Scheme

You are using a prefix length of 16, so the first 2 octets (e.g. 10.1) are the network portion of the address. I don't see what you would gain by making the change, you will still have 4 subnets, ...
Nathan Foley's user avatar
3 votes
Accepted

What does 0.0.0.0/0 mean?

It literally means all or any hosts - 99.99% of the time. The only exception I can provide at hand is the whitelist of Cisco routers, where such "zero whitelist" means negating all hosts. It ...
shodanshok's user avatar
  • 50.5k
3 votes

Can fail2ban-client tell me if an ip from a CIDR range is in a jail?

There is a nifty little tool grepcidr that is useful for quick shell scripts that need to find matches from a specific CIDR in a list with IPv4 or IPv6 addresses. sudo iptables -L -n | grepcidr &...
Johhnie's user avatar
  • 233
3 votes

Identifying subnet bits of network addresses with same CIDR

Classful networking was obsoleted in 1993 by RFC 1518/1519. Please leave network classes in the history drawer where they belong, they are irrelevant. They all have CIDR of 30. There is no such a ...
Zac67's user avatar
  • 11.5k
3 votes
Accepted

What does the netmask in an IP address actually tell you?

You can aggregate networks to one by using more little mask. It is used only for routing or in firewall rules. By example: 25.0.0.0/8 - NewYork 25.47.0.0/16 - Brooklyn 25.47.130.0/24 - Bob's house ...
Mikhail Khirgiy's user avatar
3 votes
Accepted

How will a router handle this destination address?

Since both #2 and #3 match, your router will use the longest prefix match, so it'll pick #3 since it has a 'longer' mask (closer, more specific match).
mulaz's user avatar
  • 10.7k
3 votes
Accepted

Using a AWS VPN for client access to an internal web-application

1) Does that CIDR need to be advertised or propagated to the client network, and how do I do that? If the VPN has dynamic routing, that means it's configured for BGP, so the CIDR for the VPC should ...
Michael - sqlbot's user avatar
3 votes

What does a CIDR mask mean in the context of "ip address add"?

You are right, this is the UNIX/Linux (and probably other operating systems) to define with one record IP address and netmask. The decoding is: 192.168.2.1/24 This is the IP address 192.168.2.1 This ...
Romeo Ninov's user avatar
  • 5,932
2 votes

Cannot get HTTPD 2.4 to start when using the Require IP command for access control

Require ip $CIDR ~ is not proper in the Options directive. The documentation is very clear about what may be in an Options directive. Require is its own directive, which can be in a Container, but ...
Colt's user avatar
  • 2,067
2 votes
Accepted

AWS queries regarding subnetting and routing

The IP stack in the kernel of a running instance is only aware of the instance's private IP address. The IGW is a 1:1 NAT device with a static map, which translates the instance's private IP to the ...
Michael - sqlbot's user avatar
2 votes

Issues with Ubuntu Network Setup

The cause of your confusion is that you mixed up the terms subnet and netmask. So if you have been given a 148.251.119.230/28 address by your provider (which is equivalent to a 255.255.255.240 netmask)...
guntbert's user avatar
  • 677
2 votes

Resource handler returned message: "The CIDR '10.0.1.0/22' is invalid

The message is correct. 10.0.1.0 is not a valid base address for a /22 network. The nearest legal values are 10.0.0.0 and 10.0.4.0. Consider the binary representation of 10.0.1.0 and a /22 netmask: 10....
Tilman Schmidt's user avatar
2 votes
Accepted

How do I route all public traffic through Wireguard but not local traffic?

Found it in a comment on a Reddit thread. AllowedIPs needs to have the following list in addition to the CIDR block of your Wireguard configuration. In my case, I've prepended 10.1.0.0/16 to this list....
cmjordan's user avatar
1 vote
Accepted

"AWS CIDR is not within the CIDR ranges of VPC", but it is?

I cannot reproduce your claim:
Mark Wagner's user avatar
  • 18.1k
1 vote
Accepted

Is it possible to communicate between different CIDRs?

Yes, subnets in your VPC can communicate by default. It is possible to provide a custom security configuration to control inbound/outbound traffic using Security Groups or Networl ACLs features. It is ...
Gaussianiks's user avatar
1 vote

Banning an IP address

whois <ip address> will typically show you the ip range associated with the IP address (you might have to put some of it into ipcalc or similar. There are a bunch of websites which will do a ...
Timothy c's user avatar
  • 396
1 vote

Finding netid in CIDR

For your address You can have 512 address in your subnet.. Your address ranging from 110.45.232.0 to 110.45.233.255 Your subnet mask will be 255.255.254.0 Answer is 110.45.232.0/23 (C) ...
Manikandan Ram's user avatar
1 vote

AWS queries regarding subnetting and routing

When you say "I have routed all the traffic in this range" where have you routed it? That's a bit ambiguous. You can't route traffic in a VPC, you route traffic in / between subnets, the internet, and ...
Tim's user avatar
  • 32.7k
1 vote
Accepted

Allowing external access to bastion hosts on aws

All computers on the internet have an IP address. A group of sequential IP addresses can be expressed as a CIDR block, of various sizes. For example 10.0.0.0/32 is a single IP address, 10.0.0.0, 10.0....
Tim's user avatar
  • 32.7k

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