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Questions tagged [ipv4]

Refers to the 4th revision of the Internet Protocol, where addresses are usually displayed in the form of dotted decimals between 0-255. Ex: 169.254.0.1

The IP address of a device is its unique identifier on a network which allows communication with that device.

Given the fact that only 2^32 IPs are available, number which is already depleted, its successor (IPv6) has officially taken over on 6 June 2012.

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MAC Address & IPv6

While MAC addresses are 48 bits, that is a lot more than the 32 bit IPv4 adresses (even counting the reserved addresses 255, 127, Class D Multicast etc ), will we not eventually run out of them? Also, IPv6 addresses may be derived from the 48 bit…
Lord Loh.
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Why is there a total length field in the IPv4 header?

Headers of IPv4 datagrams feature a field called total length coded on 16 bits. As there already is information about the header length of the datagram, having the total length seems redundant: it can be computed by substracting the header length…
qdii
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Getting DNS replies for non-existing hostnames (DNSMasq)

I noticed some 'weird' DNSMasq behavior when I set up my LAN for dual stack IPv4 & IPv6 networking. It seems that my DNS server (DNSMasq) which acts as a forwarder and also has all the host names for the static leases for the local network, replies…
QNimbus
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textbook CIDR subnet problems, the real world, and Cisco ip route

Assuming CIDR and classless addressing, the CCNA books I'm reading say Pearson 640-822 official cert guide 2012, pgs 403-404: According to their method S = P - N (subnet, prefix, host bits respectively). In this case S = 8 - 24 < 0. CCNA guide…
T. Webster
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ngnix startup isse ipv4 & ipv6

I'm trying to get my first nginx server setup, and am having trouble setting up ipv4 and ipv6. I have this in the top of my config file (it's the only server block in the config file): server { # Listen for requests on these ports …
gbuckingham89
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Can I configure routing to a host with public ip address via a private network?

This question has alread been posted on stackoverflow (https://stackoverflow.com/q/14904325/2012441) but since I recognized that it might be offtopic there, I'll repeat it here: I'll explain the current situation first and then I'll describe my…
mschenk74
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Assigning two IPs to one NIC in CentOS

I have been following this method described here: http://linuxwave.blogspot.com/2010/01/setting-virtual-ip-in-centos.html To assign a virtual IP to one NIC. Basically I copied ifcfg-eth0 and makde it ifcfg-eth0:1, set a new device name and IP…
Shiroi98
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Is there an IP v4 address that can never be assigned?

I am aware of the difference between public and private ipv4 address space. My question is, is there a valid (in terms of DNS) IP address which will never be resolved by definition? localhost or private address spaces are not a solution as…
Martin
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How to enable TCP/IPV4 disabled on LAN via command prompt

I have unchecked tcp/ipv4 protocol from LAN properties & now iam unable to access the server or connect remotely. However i have serial console access to the server where i can use netsh command. Kindly advise as i am stuck since 3 days & also i…
user139626
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IP address in production server suddenly conked-out

Here's the situation: my company runs a website, but we don't have anybody in-house qualified to be a sysadmin, so when something goes awry, we're very much at the mercy of our hosting provider's helpdesk.* We're having a severe problem with our…
BlairHippo
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Running IPv4 program in IPv6 network

I have an IPv4 windows client program and IPv4 Linux server. What I need is to run them in pure IPv6 network, although machines have dual stack. At the beginning I thought it's not a problem: I'll use 4in6 protocol (rfc2473) and that's all. I found…
stobyer
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Transparent SOCKS5 proxy for linux using dual stack IPv4 and IPv6

Can you recommend a SOCKS5 proxy for linux that can accept IPv4 requests, but connects to the internet using dual stack (IPv4 and IPv6)? It is going to run on Ubuntu with dual stack enabled. I thought of squid, but how does it have to be…
pintpint
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Iptables: Drop all incoming IP4 traffic on a port

I want to drop ALL the ipv4 traffic on a certain port and only allow ipv6 traffic with iptables. Is it possible? is so, how?
Alejandro Garcia
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what is giving me a backwards IP address?

This is the background: https://superuser.com/questions/400298/cause-of-intermittent-smtp-emailing-sending-problems In short Outlook (2007 IIRC) was receiving the wrong IP address for the SMTP server domain - it turned out that the address was…
pbhj
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What transport protocols can be routed properly over the Internet, other than TCP and UDP?

I recently noticed that my ISP doesn't like routing native SCTP traffic over the Internet, unless it's tunnelled through UDP. A bit of a pain, but I solved the issue by using tunelling. This issue got me thinking - other than TCP and UDP, which…
Polynomial
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