Questions tagged [ipv4]
For questions about Internet Protocol version 4 (IPv4); as specified in RFC791.
883
questions
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can teach me how to use whatweb or nikto [closed]
now I am doing the penetration Test but I am 0 basic in cyber security so can someone help me explain the picture I provided is that website getting the error when using the tool is kali lunix nikto ...
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1
answer
40
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IP fragmentation and PMTUD
I have 2 questions.
1) According to a lot of sources, when IP packets gets fragmented, in this case, lets take icmp, the icmp header is present only in the first packet.
But I have observed on some ...
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1
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60
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Would a /24 public ip range typically be from the same country?
Would a /24 public ip range typically be from the same country? This to reduce the amount of ipstack requests, checking from what country an IP is. (due to bot requests)
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1
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46
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What is hiearchy of IP addresses? [duplicate]
What is structure/hiearchy of IP addresses?
I mean, is mandatory that IP address e.g. 216.9.10.0 is subnet of 216.9.0.0? Of course many times that is the case and IMO it would be logical, but I have ...
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19
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In IPv4, why does a /16 network has 256 /24 networks? [duplicate]
I wish to validate my understanding regarding the following statement:
With IPv4, a /16 network has 256 /24 networks.
The following is my train of thought:
An IPv4 address consists of 32 bits, and ...
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1
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1
answer
63
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Wrong subnet configuration works anyway in a shared bus, but doesn't work in switched lan. Why?
I was told that this configuration (which contains an error in DNS mask which is /23 instead of /24) works only because it's a SHARED bus. If it was a SWITCHED lan, the DNS responses from DNS to A ...
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3
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5
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2k
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IPv4 class E IPs
can someone explain to me why we cannot use the class E IP space? I know it's reserved but this is a huge chunk of IP addresses they could make available. Would this bring such huge issues that it ...
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about subnetting ip adress 172.16.0.0 [duplicate]
can you explain why we have 172.16.0.0 to 172.31.0.0 so it can't be for example 172.13.0.0 to 172.35.0.0.
And also why is 192.168.0.0 and is it possible to be 192.160.0.0? thank you
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1
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41
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Geolocation specific ASN
question: is it possible to determine the geolocation of a city/region of a specific ASN? For example, Telecom Italia has many ASNs. Is it possible to know for each one "which soil" they ...
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1
answer
81
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I want to set up a MSTP Redundant Network
For the past few days i have been trying to get multiple VLan's working that are redundantly connected. One VLan would be connected through a controller and to the other switch. Then a second cable to ...
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1
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68
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Get all reachable IP addresses within a private network [closed]
Is there a way to get all reachable IP addresses within a private network. I know that we can get all active devices' IP addresses within same subnet using arp.
I was wondering if something similar ...
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2
answers
51
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How do you assign sequential IP addresses to individual ports on a switch? [duplicate]
I am looking for a non-complicated way to set up a network of 50 interchangeable devices such that whenever I plug a device into a specific port on a switch, I will always get the same IP address ...
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0
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2
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78
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Communicating to a device with a random IP, Subnet Mask and Gateway
I think am looking for a way to reliably communicate with devices connected to the network with "wrong" configurations.
Our company sells products that can have their network settings ...
1
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1
answer
174
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Explaining the entries in routing table
I would like to ask for help with explaining every particular entry in routing table. That is what I receive after calling route print in my PC, based on Windows:
So my understanding is:
0.0.0.0 ...
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2
answers
83
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Communication with different subnet masks
So I try to explain the dilemma.
I have 2 groups of clients and one server.
I want these groups to only communicate with the server.
This means that each device in these groups should see the server, ...
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0
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2
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54
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Advertising IP prefixes to the internet using BGP
I am studying BGP at the moment.
From what I've learned, in order to participate in routing on the internet and use BGP, we need to register a public provider-independent IP address block and a public ...
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1
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65
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how does a router know an ip address's network prefix when it comes to CIDR
Let's say I start a new company and lease a block of ip address 222.123.123.0/25 from Internet registry, so one of those ip address 222.123.123.4 is my main web server. A customer from a different ...
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1
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219
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Understanding IPv4 model of operation
I'm new to networking and reading RFC791 about IP protocol specification and got some question regarding the paragraph 2.2 Model of Operation. Here is what is discribed:
The internet module prepares a ...
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1
answer
68
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Why are BGP tables suddenly filled with IPv4 routes?
According to article I looked at, bgp routing tables are approaching a maximum size and this is linked to IPv4 exhaustion. Why is this problematic and what is the cause? Will this be a problem with ...
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0
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82
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Nonsense RFC 4604 forbids IGMP General Queries in SSM range but IGMP General Queries have no range and are send to 224.0.0.1, the all-systems address?
RFC 4604 Using Internet Group Management Protocol Version 3 (IGMPv3) and Multicast Listener Discovery Protocol Version 2 (MLDv2) for Source-Specific Multicast:
2.2.3. IGMPv1 Queries, IGMPv2 and MLDv1 ...
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3
answers
165
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Can I use the network and broadcast IP addresses of a /24 subnet, when the /24 subnet is included in a larger /22 subnet range for NAT?
I'm wondering if I can use the network and broadcast IP addresses of a /24 subnet, when the /24 subnet is included in a larger /22 subnet range for NAT?
PS: Please consider that 198.51.0.0/22 is ...
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1
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59
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What is the RFC 791 64 octet header?
I'm trying to understand the PDU sizes as it traverse the TCP/IP model.
RFC 791 says the IP protocol is required to accept datagrams of 576 octets. ( 512 octets, plus up to 64 header octets). I know ...
1
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1
answer
49
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Maintenance access to customers over VPN with same network on each side
We are a small company that manufactures machines for the industry. What I need today is an access to the machines when they are in our workshop (construction and adjustment) but also, and this is ...
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1
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2
answers
71
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Is it a thing to subnet an address but still use initial network host?
Hei,
Suppose we have 192.168.0.0/24 and we subnet it as 192.168.0.0/25. Is it a normal thing to configure hosts with IP addresses in both /24 and /25 address spaces ? We consider /24 and /25 to be in ...
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1
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2
answers
198
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Practical uses of directed broadcast
What are directed broadcast addresses used for in practice?
To be clear, an example of a directed broadcast address is 192.168.1.255 for the network 192.168.1.0/24. On the other hand, the limited (or ...
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1
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2
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227
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How does subnetting solve the problem of IPv4 address shortage?
Reading articles on the web, they all say that "subnetting solves the problem of IPv4 address shortage by dividing a large physical network into multiple smaller networks". I do not ...
- 135
0
votes
2
answers
716
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UDP fragmented packets not reassembled
I have been working with a device that sends me UDP packets heavily.
I'm trying to capture those packets in my Linux machine (Ubuntu 22.04.2 LTS) with Python programming language.
But, most of the ...
1
vote
1
answer
60
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CISCO cellular Router cannot reach network via my PC
I configured the cellular and my router is connected to the internet ping (5/5) Success
but I still cannot access the internet via PC
Here is my running-conf
Current configuration : 2271 bytes
!
! ...
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1
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107
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Tracing a route, from 127.0.0.1 through my network to 20.43.161.105
Greetings in the name of network engineering!
BACKGROUND:
The IPV4 network consists of the following nodes:
Node 0:127.0.0.1
Node 1:10.1.1.1
Node 2:192.168.0.1
Node 3:192.168.1.1
Node 4:210.x.x.x
Node ...
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5
answers
101
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Are there any methods of differentiate between a single computer and a NAT router?
As far as I know, a traffic from a NAT router should appear similar to traffic from one computer with a single IP address. If you do not have any access to a network (let's say you are an ISP), can ...
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1
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66
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Can, and should, a link local address be used for a gateway in IPv4? [closed]
I was just experimenting with IPv6 and hypervisors, where I made productive use of the IPv6 link local address to route packets towards a tap device to establish communication with a virtual machine.
...
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0
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1
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629
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Sharing same IP address inside LAN? [duplicate]
Q: if 2 devices A and B share same ip address in LAN, can device A retrive all messages whose destination is device B?
I think this depends on how the LAN is configured.
If it's wireless then device A ...
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0
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1
answer
106
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RFC 1918 nonsensical sentence
I am doing an intern and now under a training. The instructor suggested us of reading the RFCs involved with the topics covered in class.
In RFC 1918, they say "An enterprise that decides to use ...
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1
answer
100
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Public and Private IP address range confusion [duplicate]
class A private IP range (10.0.0.0 to 10.255.255.255)
class A public IP range (1.0.0.0 to 127.0.0.0)
In these 2 public and private IP ranges, the private IP range is also included into the public ...
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0
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0
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9
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Identify first six /49 blocks out of ABCD::/32 [duplicate]
The answer is given as
ABCD:0000:0000:0000:0000::/49
ABCD:0000:0000:0000:8000::/49
ABCD:0000:0000:0001:0000::/49
ABCD:0000:0000:0001:8000::/49
ABCD:0000:0000:0002:0000::/49
ABCD:0000:0000:0002:8000::/...
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1
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89
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How do I configure a Cisco router to relay DHCP packets to DHCP server on the basis of different VLAN?
Running-Config of RO1
!
interface GigabitEthernet0/0
ip address 192.168.25.26 255.255.255.0
duplex auto
speed auto
!
interface GigabitEthernet0/1
no ip address
duplex auto
speed auto
!
interface ...
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1
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0
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25
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Complicated bridge between 2 servers [closed]
I have 3 servers:
comp_a, comp_b, comp_c
comp_a ([eth0 «10.15.14.55»]) 10.0.0.0/8 <———> comp_b ([eth0 «10.15.27.61», eth1 «10.15.26.61»] [eth1 «10.15.26.61» ]) <——VPN IPS (left = 10.15.0.0/16 ...
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1
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Valid uses for IPv4 Options [Community-Wiki]
Engineers building firewall rules often block all IPv4 packets with IPv4 Options set in the header. However, there are a few common and valid use-cases for IPv4 Options.
This Q&A is intended to ...
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114
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Public IP Configuration which has a private gateway
I bought a public IP from my ISP and they provided me with the following details.
WAN IP :10.129.69.157
LAN IP : 196.188.173.32/30
How do I configure this on my side ?
The told me to do configure as ...
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11
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3
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Is `0.0.0.0/1` a valid IP address? If so, what does it indicate?
I know that 0.0.0.0/0 represents a default route.
But I would like to understand what does 0.0.0.0/1 represents? Is it even a valid thing in networking?
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61
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Can't find a device on my network [closed]
I have a device on my network that is at a static address (192.168.3.1). This device is connected to a network switch, that is also connected to the rest of my network. My problem is that I need to be ...
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2
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626
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Cannot ping/access single host over VPN [closed]
I am running openVPN server on pfSense machine, which is also the router of the network. This network has several VLAN's, where only single one of them is of interest - 10.0.100.0/22.
The openVPN ...
0
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1
answer
84
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How to correctly setup a DHCP server in the following network?
So, I've got the following Network Configuration:
Assume that, on the graph, "PCs" can be any device that needs an IP(apart from a router).
Now, as explained on my title, I want to run a ...
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0
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1
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717
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How to connect GNS3 to loopback adapter on Windows 10
I'm trying to have a simple topology by connecting a router (c7200) and the local machine which is windows 10. For this I use GNS3 GUI (not the VM application). I have to do that, due to the limit of ...
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0
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1
answer
109
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Packet tracer overlapping error [duplicate]
I'm very new to packet tracer (day 3) I seem to get an overlapping error message, on 0/0/0 - 192.168.0.2/24, I couldn't assign 0.3 to interface 0/0/1 (overlapping) so I assigned 0.3 to PC0 and tried 0....
0
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3
answers
236
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Lost the Static IP/network settings of a device
We have a physical device (lab instrument) that we can only connect to via ethernet. Unfortunately a static IP was set with network settings and these settings has been lost.
We connected our computer ...
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2
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688
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Access to systems with the same IP address but various port number in another network?
I have some knowledge of networking but not much, so I appreciate knowing from the experts.
modified part
I have 10 devices(PLCs) with the same IP address "192.168.42.2" that I want to ...
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5
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2
answers
478
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Does the IP header have a "Padding" field?
I found two images of the IP header, one image shows a field called "Padding", while the other image don't show the "Padding" field:
Which one of these two images is correct?
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1k
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What is the Logic of AND and OR operations in subnetting?
To calculate subnetting for given IP address and the subnet address, we do AND operation first to get the network address and the first usable IP address of the subnet. Why do we use AND? I know it ...
0
votes
1
answer
58
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Is it possible to send network messages with "Fake" Local Network(192.168.x.x) destination IP but actually reaches the destination via internet?
I am configuring a MySQL server that is only intended for computers from internal network/local network machines to access.
Now MySQL has a "bind IP address" setting that, if I set it to the ...
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