Questions tagged [cidr]

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

I'm attempting to learn to set up Wireguard properly (not just by copy-pasting). I've come across this line on the quickstart page: ip address add dev wg0 192.168.2.1/24 Reading the man page for ip, ...
Clonkex's user avatar
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1 answer
548 views

Adding more IP Addresses to a Subnet in AWS

I have a Subnet with CIDR 10.0.4.0/28 (15 IP addresses), which is now exhausted; so I want to add more IP addresses. Is it possible to add more IP addresses to the subnet? I see that I can add a ...
Techboy's user avatar
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2 answers
119 views

AWS CIDR Address is not within CIDR Address from VPC

In AWS have created VPC which CIDR is 10.0.0.24.I want to creates its two subnet.its public-subnet is in us-west-1a - IPv4 CIDR 10.0.0.0/24 thenwhen I create private subnet is in us-west-1b - ...
Developer.Sumit's user avatar
0 votes
0 answers
445 views

How to update podCIDR for Kubernetes master node without recreating it

I have installed a Kuberntes system with one node,the node itself worked as both work node and master node,now I met a problem: When the pod num exceed 255,Kubernetes will failed to deplopy it,after ...
flyingfox's user avatar
  • 101
1 vote
3 answers
3k views

Check if IP Belongs to a CIDR

We have a list of CIDR's 1.10.10.0/24 5.154.0.0/16 5.181.219.0/24 23.90.68.0/24 31.40.214.0/24 I want to check if a IP for example : 23.90.68.56 belongs to any of the above CIDR's. If yes then we get ...
ph3ro's user avatar
  • 145
0 votes
1 answer
1k views

AWS VPC Subnetting

I have a VPC created with a CIDR block of 10.10.0.0/16. I am trying to subnet that block into some /24's -- ie. 10.10.1.0/24 It wont let me. The error I get is: CIDR Address overlaps with existing ...
mikem's user avatar
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1 answer
6k views

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

I know there's a series of CIDRs that I can use to cover all public CIDRs and leave out local CIDRs, but I cannot find this anywhere and I don't recall where I found it a couple of years ago when ...
cmjordan's user avatar
1 vote
2 answers
380 views

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

I'm getting this error while trying to create a VPC with a Subnet in CloudFormation. Subnet CREATE_FAILED Resource handler returned message: "The CIDR '10.0.1.0/22' is invalid. (Service: Ec2, ...
André Chrisostomo's user avatar
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1 answer
392 views

What does 0.0.0.0/0 mean?

For example in an 'allow' statement in BIND or in Chrony config files. Does allow 0.0.0.0/0 mean allowing any clients or allowing no clients? My question isn't about the specific programs, but just ...
madacoda's user avatar
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1 answer
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"AWS CIDR is not within the CIDR ranges of VPC", but it is?

many questions on this, but this time doesn't seem as obvious as the others. I'm trying to split a VPC in two subnets. I start with VPC 10.0.0.0/24, 254+1 IPs, from 10.0.0.1 to 10.0.0.255 I create the ...
gabriel's user avatar
  • 103
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1 answer
316 views

Is it possible to communicate between different CIDRs?

For example, there are two CIDRs in the same VPC on AWS. One of them is public and one is private. They are in the different segment. # Public Subnet CIDR 10.124.42.0/27 # Private Subnet CIDR 10.124....
Miantian's user avatar
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1 answer
507 views

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

If I have a CIDR like 13.54.63.128/26 can fail2ban-client tell me if there's an IP in this range that's currently banned? Currently I'm doing: CIDR="13.54.63.128/26" nmap -sL -n $CIDR | awk '...
jaygooby's user avatar
  • 324
-2 votes
2 answers
87 views

Identifying subnet bits of network addresses with same CIDR [closed]

Say we have network addresses 10.10.10.252/30 and 10.10.255.252/30 and 10.255.255.252/30. They all have CIDR of 30. I realize all three subnets have two usable hosts. All three addresses have subnet ...
Logan Lee's user avatar
  • 149
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2 answers
5k views

Issues with Ubuntu Network Setup

Please, someone tell me whats up here, I am going bonkers, I have used multiple calculators etc, everything tells me the details in the image are correct but ubuntu just will not accept.
Ron Appleton's user avatar
-1 votes
1 answer
274 views

Banning an IP address

I banned an IP on my server, but I'd also like to ban using the CIDR method, e.g. IP/24. My questions are: How do I find the CIDR range of the IP address. When banning the range, if the user has a ...
Usernamehere's user avatar
4 votes
2 answers
8k views

What is a correct IP4 CIDR for AWS?

I am trying to create some new subnets and cannot get AWS to accept a CIDR IP4. I receive the message: Must be valid IPv4 CIDR. Nothing I try is accepted. What is a valid IP4 for this purpose, and why?...
Leon's user avatar
  • 143
3 votes
4 answers
12k views

AWS VPN Client connection to new VPC Endpoint is failing

I have set up a new VPN following the guide here. However when I try to connect to the VPN with the client i get an error "Connection failed. Try again." This happens every time. I opened the log file ...
Salbrox's user avatar
  • 51
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0 answers
740 views

How to connect a VM to the Internet in VMware vCloud using a Network Gateway CIDR

I am familiar with managing servers and VMs that have their own IP address and network connection, but am now trying to host a VM in a VMware vCloud and am a newb for this. I have created the VM and ...
James's user avatar
  • 11
0 votes
1 answer
218 views

Finding netid in CIDR [closed]

I am practicing questions related to CIDR and I have come across a particular question which I need some explanation. Can somebody please explain in detail how to answer this question. An address ...
salman's user avatar
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0 votes
0 answers
117 views

How to get range of ip addresses of current network

I am using AWS to host my website, recently I've been getting a lot of background noise on the server (bots trying to backdoor, etc.). I would like to limit access of my website to just our worksites ...
David's user avatar
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0 votes
1 answer
292 views

What is the VPC accepted address and why [duplicate]

i am trying to create a vpc but the ip i am providing is not accepted which is 192.168.1.1/16 but aws says i can use the following range if i set to 192.168.0.0/16 it works , i guess to an extent ...
akash's user avatar
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3 votes
2 answers
15k views

Is it possible to change CIDR network flannel and Kubernetes

Is it possible to change CIDR network flannel on running Kubernetes cluster? If yes what will happen with the launched pods? Thanks
Kris454's user avatar
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-2 votes
1 answer
347 views

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

My public IP address (of my personal computer) from which I access the internet ranges from 112.110.x.x. For experiment, I created a VPC in AWS and chose the CIDR block as 112.110.0.0/16. In the route ...
Sanjay Vig's user avatar
0 votes
1 answer
835 views

Allowing external access to bastion hosts on aws

I am trying to create a few bastion hosts in my VPC on aws to connect to my databases that are located in a private subnet. I am using this aws Quick start. I understand the basics of CIDR blocks ...
Marwan's user avatar
  • 103
0 votes
2 answers
85 views

Subnet CIDR Scheme

I am redoing some VPC work that my predecessor did. I haven't setup a lot of networks, so I wanted to double check what I think makes sense isn't breaking some rule that I'm not familiar with. What ...
Joshua Banton's user avatar
3 votes
1 answer
988 views

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

The range of 0.0.0.0/7 is 0.0.0.0 - 1.255.255.255. The range of 1.0.0.0/8 is 1.0.0.0 - 1.255.255.255. AFAIK, 0.0.0.0/8 (0.0.0.0 - 0.255.255.255) is not usable. So, do these represent the same range ...
Szymon Marczak's user avatar
0 votes
2 answers
43 views

AWS queries regarding subnetting and routing

I have some queries regarding AWS setup please clarify. I have created a VPC with CIDR 172.16.0.0/16 which is a private range of IP's. In my route table, I routed all the traffic from this range. ...
mekala Aravind's user avatar
3 votes
7 answers
2k views

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

There are several questions out there asking what the CIDR netmask is, and how it's calculated. But after reading all the top answers, I'm still left wondering, how does the netmask let us distinguish ...
CodyBugstein's user avatar
0 votes
1 answer
3k views

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

I'd like some help understanding subnets (CIDR). I'm using a tool to check if an IP is in an acceptable range given a CIDR address. When I input an IP address (12.245.105.190) and check it against ...
Isaac Lubow's user avatar
1 vote
0 answers
755 views

Adding exception to nginx HTTP basic authentication based on being on the local network

I'm running an installation of a webapp running on a self-hosted server which is on my main network along with all our company PCs and a couple of other servers. We've decided we want to add HTTP ...
shaneoh's user avatar
  • 424
0 votes
1 answer
847 views

fail2ban - Filter IPs by cidr blocks

I'm using fail2ban 0.10.0 and with it I'm able to trigger some actions to block bruteforce attempts from a given single origin (with the HOST tag). But suppose someone has control over an entire /24 ...
Daichi42's user avatar
0 votes
1 answer
43 views

How will a router handle this destination address?

Let's say I have a router with three interfaces. Interface #1 is 10.x.x.x /8 Interface #2 is 142.100.48.x /20 Interface #3 is 142.100.56.8 /21 I'm trying to send a file to [dest]142.100.57.5 from [...
Chef Flambe's user avatar
1 vote
1 answer
126 views

How can destination addresses 132.148.77.28 and 132.148.77.28/32 be use different network interfaces for routing?

The output of netstat -rn on my FreeBSD virtual machine shows that: Internet: Destination Gateway Flags Netif Expire default 10.195.51.254 UGS vtnet0 10....
papiro's user avatar
  • 159
0 votes
1 answer
2k views

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

This was intended to be a comment on a similar question but since Stack is so restrictive about comments I'm reposting it as they want it: : Here's the documentation: http://httpd.apache.org/docs/2.4/...
eco's user avatar
  • 147
-9 votes
0 answers
2k views

AWS Reserved IP addresses [closed]

I have multiple VPC in my account and I created most of VPC using subnet 10.0.0.0/8 or 192.168.0.0/16 or 172.16.0.0/12 subnet blocks. I am exhausted with my range due to not optimizing the IP ...
Pratap's user avatar
  • 705
0 votes
1 answer
561 views

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

I'm trying to connect a client's network to our AWS data-centre, to allow access to a (previously publicly available) internal web-application. At the moment we've got the VPN set up with dynamic ...
user705142's user avatar
4 votes
1 answer
7k views

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

I'm trying to launch an instance with the private IP address 172.31.32.101 using Terraform in my default VPC (CIDR 172.31.0.0/16), in the eu-west-1a subnet that has the CIDR 172.31.32.0/20. I can ...
scrossan's user avatar
0 votes
1 answer
2k views

Connecting two AWS VPC Regions of the same CIDR range

Let say I have two VPC's (VPC-A with 10.50.0.0/16 and VPC-B with 10.50.0.0/16) in AWS with same conflicting/overlapping CIDR ranges in my AWS account. I already have the two VPC's fully functional ...
Aadesh's user avatar
  • 101
0 votes
0 answers
156 views

Can foreman handle nested subnets?

In Foreman 1.8 one can manage subnets through the web-interface at Infrastructure > Subnets. However, when I add a /24 (e.g. 10.10.0.0 with a subnetmask of 255.255.255.0), I cannot add anything less ...
alboe's user avatar
  • 1
-2 votes
2 answers
8k views

What's the difference between .0/32 and .1/24 in CIDR? [closed]

We're specifying CIDR addresses in AWS rules, and I came across something I don't understand. /32 means one single address. So 10.0.0.0/32 means only the single address 10.0.0.0. But an address ...
pabo's user avatar
  • 115
57 votes
6 answers
57k views

What is the recommended CIDR when creating VPC on AWS?

I have been creating AWS VPCs and I am wondering if there is a recommended CIDR value when creating VPCs. What are the factors that I must consider when choosing a CIDR and does the CIDR value affect ...
Gene Diaz's user avatar
  • 727
0 votes
2 answers
16k views

Google IP Address Ranges for incoming SMTP [duplicate]

Essentially I'm answering my own question here, but want to provide this info to anyone else who might need it. I need all the valid IP address ranges for Google Apps mail servers. I'm configuring a ...
dmarietta's user avatar
  • 519
16 votes
5 answers
3k views

Are Cisco admins expected to understand classful networks?

While studying for the CCENT exam, my reference materials have made an alarming number of references to class A/B/C networks. Thankfully they just treat Class A/B/C as shorthand for /8, /16, and /24 ...
YouAreTheHat's user avatar
-2 votes
1 answer
158 views

SOHO Routers and Non-Standard CIDR Blocks [closed]

I recently learned about private networks. From what I understand there are three address ranges for use in private networks: 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16 If this is the case, then why on ...
AlfaZulu's user avatar
  • 595
2 votes
2 answers
2k views

Why does the Cisco RV180 not let me use a 255.255.254.0 subnet mask with a 192.168.2.1 LAN IP address?

I'm a Sysadmin for a tech company. We have a Cisco RV180 gateway device. We are at our breaking point for IP addresses, so we are changing from a /24 to a /23 subnet to allow for double the devices. ...
Dustin Dauncey's user avatar
0 votes
1 answer
415 views

Using a CIDR range as a Routed Subnet?

I have a /29 subnet assigned by my ISP, with an SonicWALL office router and a Cisco voice router hooked up to a 'net-rail' of sorts with untagged VLAN switch ports connecting my ISP router's output ...
Craig Watson's user avatar
  • 9,680
1 vote
2 answers
256 views

How to reserve first 32 hosts in IP address range

I am using NoDogSplash which is a captive portal, meaning it redirects your packets and forces you to authenticate before you can access the Internet. It does this in an isolated 10.0.0.0 network. Now,...
derringer's user avatar
2 votes
2 answers
3k views

How do I divide a network into smaller subnets using a single Layer 3 switch?

I have had trouble searching for help on this one, as most searches for VLSM, CIDR and layer 3 switching bring back very basic questions posted by students just starting their CCNA. I have a batch of ...
sram's user avatar
  • 23
4 votes
2 answers
339 views

Is this IPv4 and subnet combination public or private? [duplicate]

Possible Duplicate: How does IPv4 Subnetting Work? I thought I understood this but I am momentarily confused. Here is an example: Are all IPv4 addresses from 192.168.0.0 to 192.168.255.255 in ...
taz's user avatar
  • 151
4 votes
0 answers
563 views

How to support VRF in Netflow Collector?

I am somehow able to analyze netflow packet using my own netflow collector (build in python). It works for certain ip and CIDR(Classless Inter Domain routing), definitely not overlapping. What is the ...
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