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Questions tagged [ipv4]

Use the ipv4 tag ONLY if the nature of your question specifically involves IPv4 addresses or networking -- often in contrast to IPv6. Most networking currently involves IPv4 addresses, so you should NOT include this tag with every networking question.

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1answer
43 views

How do I use grep to output only the names of files that contain any ipv4 address

I am using Red Hat Enterprise 6 and I'm trying to search through the /etc/ directory for files that contain any IPv4 address.
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2answers
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Do the default settings of NetworkManager detect if there is a conflicting IPv4 address on the network?

Added support for detecting duplicate IPv4 addresses, with a timeout configurable through the ipv4.dad-timeout connection property. -- NEWS dad-timeout / int32 / -1 Timeout in ...
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1answer
84 views

does :::80 in netstat output means only ipv6 or ipv6+ipv4?

If I am listening on :::80, is it listening on all ipv6 or all ipv6+ipv4? This is my netstat -tln: tcp 0 0 :::8080 :::*
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0answers
15 views

Getent Hosts For Port 1915/tcp -iptables

I have a scenario: i will have to protect my network from unsolicited access from my DMZ machine, configure node-A to allow new connections on port 1915/tcp from hosts (obtained by 'getent hosts node-...
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1answer
23 views

Get Wireless LAN IPv4 Address Of Device

I want to know the easiest way and I would perfer a single line command that works on most or all Linux distros. I want to get the devices IPv4 address. The reason why I want to know this is because ...
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0answers
19 views

Cannot connect with IPV4 servers [closed]

IPV6 works fine, but IPV4 does not. I can: resolve dns names just fine (dont think its an dns issue) I am connected to the AP correctly (dont think its a connectivity issue) I have a IP address (...
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3answers
53 views

How can check ipv4 address in shell. Like is it *.*.1.* or *.*.0.*?

So here I tried to get from the ifconfig file, but same with errors with simple ifconfig command !#/bin/sh if [/home/pi/ifconfig | grep -Eo ‘inet (addr:)?([0-9]*\.){3}[0-9]*’ | grep -Eo ‘([0-9]*\.){3}...
2
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1answer
178 views

IPv4 and IPv6 sockets with same port

Is it possible to have a single process that would have two sockets, one using the AF_INET and one using the AF_INET6 families, while both being bound to the same port number, e.g. 20000? If the IPv6 ...
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0answers
23 views

Question about IPv4 when installing DragonFly latest/5.2.2

Someone told me to take a look at DragonFly BSD recently and I decided to take it for a spin. I downloaded the latest bzip'd ISO from their website and wired that ISO up to a VirtualBox VM. I checked ...
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2answers
133 views

iptables blocks SSH connection

I've recently upgraded my Raspberry Pi from Raspbian 8 (Jessie) to 9 (Stretch). The Pi in accessible on my LAN both via IPv4 and IPv6. I have applied some iptables rules (IPv4 only) to block hosts ...
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1answer
43 views

IPv6 superuser ports

Does IPv6 have the 0-1024 superuser requirements for ports? I saw in the changelog for Linux 4.11 that they added a sysctl option to change it, but it only lists it under IPv4. Also does Open/FreeBSD ...
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0answers
52 views

iptables ipv4 configuration for OpenVPN Connectvity

I'm following this tutorial in order to setup my openvpn server: https://linode.com/docs/networking/vpn/set-up-a-hardened-openvpn-server/ When i reached the part to replace the ipv4 configuration, ...
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9answers
3k views

Bash: Extract one of the four sections of an IPv4 address

We can use the syntax ${var##pattern} and ${var%%pattern} to extract the last and first section of an IPv4 address: IP=109.96.77.15 echo IP: $IP echo 'Extract the first section using ${var%%pattern}: ...
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1answer
1k views

IPv6 socket creation failed: Address family not supported by protocol

OS: GNU/Linux Debian 9.2 64-bit I disabled IPv6 on one of my servers. And now I'm getting this in mail: exim paniclog ... IPv6 socket creation failed: Address family not supported by protocol How ...
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0answers
244 views

SSH Tunnel broker over IPV4 for machines behind CNAT

I am not sure if I should be asking this in Unix & Linux or Network Engineering Here is the physical scenario [Host 1]----[Carrier-grade NAT]---->AWS<----[Carrier-grade NAT]----[Host 2] ...
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2answers
1k views

Using Linux as router with nftables - masquerade not forwarding reply back

I have a Linux machine which I'm using as a router. It has 5 network interfaces: three separate LANs which it routes between, and two WANs. At the moment I just have one WAN as the default route, and ...
2
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1answer
4k views

How do i check if DHCP is enabled?

I have a VM running Debian 9 and the latest version of VirtualBox. I have VirtualBox configured to use the bridged adapter and it was working fine yesterday. But when I came and got on it this morning....
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1answer
545 views

Get DHCP running with Kernel 4.14-rc5

I tried to solve my problem that my touchpad is not running on my Lenovo 720-15IKB by installing the latest rc kernel 4.14.rc5 as described here, which really worked! The touchpad is working then! ...
1
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1answer
911 views

Not getting dynamic IP address by dhclient on a virtual Fedora

I run a course that includes practical classes on system administration. For that years ago I created a Fedora 20 virtual image -- it need not be a modern and secure one as it is only for executing ...
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2answers
8k views

Apache server not listening on IPv4 but listening on IPv6

We are facing one weird problem on one of our RHEL apache server. Actually, it is not listening on port 80 from remote hosts. When we locally browse http://localhost it is opening default page. When ...
0
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1answer
110 views

What is ICMP reply for all-zero host-bit IPv4 address?

We all know that the first address of any sub-net is network identifier and it can't be assigned to any hosts. For example in network 10.1.1.4/30, the address 10.1.1.4 is network identifier. If ...
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0answers
2k views

vsftpd works with ipv6 but not with ipv4

I am running an ftp server via vstfpd. /etc/vsftpd.conf: listen=YES #listen_ipv6=YES anonymous_enable=NO local_enable=YES write_enable=YES use_localtime=YES xferlog_enable=YES #...
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1answer
4k views

Change the listening address to IPv4 from IPv6

I use netstat -plnt check the vsftpd deamon, it is listening the IPv6(tcp6) address, so I use the FileZilla can not connect the VM. [root@localhost src]# netstat -plnt Active Internet connections (...
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1answer
3k views

wget uses ipv6 address and takes too long to complete

On a server wget-1.16 takes 8 minutes to complete: $ wget http://http.debian.net/debian/dists/stable/Release -O - --2017-06-12 23:44:40-- http://http.debian.net/debian/dists/stable/Release [...
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3answers
129 views

Find local processes starting TCP connections

With tcpdump I see many SYN packets ... and source IP is Localhost. I wish to find which processes are trying to connect. Note the connections don't reach ESTABLISHED state, they seems to be random ...
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1answer
448 views

Routing packets between IPv4 and IPv6 networks on different Interfaces

I have a Linux-Board with two Ethernet-Interfaces (eth0, eth1). On eth0 I have a IPv4 network, on eth1 there's a IPv6 network. Now I want to route packets from specific devices on the IPv4-network to ...
2
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1answer
434 views

Why is BIND not automatically trying all nameservers, especially when an IPv6 nameserver is unreachable?

I am running a recursive local name server using BIND on Ubuntu. I have an IPv4 network at the moment. It appears as though BIND defaults to listen for queries and recursively resolve names on both ...
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1answer
704 views

Mapping IPv6 to IPv4 addresses

I'm trying to figure out what commands I can use to help me map IPv6 to IPv4 addresses on a local network. I would like to be able to do the operation both ways (IPv4 -> IPv6 and IPv6 -> IPv4) where ...
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2answers
410 views

iptables limit the number of connections in the system for both ipv4 ipv6

A connection is a 5 tuple (ip src/dst, port src/dst, protocol). What about different connections between ipv4 and ipv6? If I define the iptables rule: iptables -A INPUT -p tcp -m connlimit --...
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1answer
7k views

Add IPv6 address to existing IPv4 interface not working

Probably a simple answer but I can't seem to find it. I am running a multihomed Debian Stable(latest) and on interface eth1 I need both IPv4 and IPv6 address. My /etc/network/interfaces looks like ...
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1answer
1k views

How does Linux choose between default gateways?

I have a computer with two NICS, one eth one wlan. wlan is on 10.0.0.0/24 eth is on 192.168.0.0/16 Kernel routing table is: $ route -n Kernel IP routing table Destination Gateway ...
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1answer
386 views

Can not resolve names but can ping addresses when connected to IPV4 router, all works fine with IPV6 router

At my place I have a router that gives me an IPV4 address. My Gentoo PC works fine but my Gentoo laptop stopped resolving names. I visited my parents and tried connecting to their router, which gives ...
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1answer
2k views

IPv6 over TCP or TCP6

My understanding is that tcp6 is used for connections over IPv6 & tcp is used for connections over IPv4. and ::ffff:127.0.0.1 is representing IPv6 address which is mapped to IPv4 address. ...
3
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1answer
786 views

Debian and Centos: why does ipv6 prevail over ipv4

Every time I am configuring a Debian or Centos machine with a static IP address, I forget about that behavior of not taking in account my IPV4 configuration. Then, I search for the 1000th time the ...
2
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1answer
2k views

Loosing IPv4 and DHCP constantly asking for IP

Using Ubuntu 16.04, almost every day I'm loosing IPv4 address, being dropped by Avahi Daemon. Also, I see the DHCP is not "waiting" for leasing time to finish to request an address again, it does it ...
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1answer
90 views

Raspbian uses the complete dhcp range

I temporarily had a static ip for my raspberry. Now the config looks like this. /etc/network/interfaces auto lo iface lo inet loopback auto eth0 iface eth0 inet dhcp But this leads to a ...
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1answer
131 views

IPV4 getting removed after restart CentOS machines

I have CentOS machines (both 6.x and 7.1) and whenever I reboot them, automatically IPV6 is assigned to them and IPV4 is lost. Any idea why it is happening and how to prevent it? I Could not ...
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2answers
134 views

Fedora Core 4 won't get an IPV4 address

I have a fedora core machine, and it is picking up an IPV6 address, but not an IPV4 address. I have done dhclient -r eth0 but the ipv4 address has not come. I have reset the port using ifconfig, but ...
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1answer
1k views

Changing the port letsencrypt tries to connect on

So, one of my servers is behind NAT, and since there is already a publicly accessible apache server going on my LAN, I decided to access it from the outside with different ports, and remap them to the ...
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3answers
6k views

Validating IP addresses (IPv4 and IPv6)

Quite simply I'd like to verify that a string represents a valid IP address in a bash script. I think like many others I've fallen into the pitfall of trying to do this with a regular expression; ...
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0answers
1k views

curl request to IPv6 localhost gets stuck

A docker container of mine exposes a HTTP interface on port 8500, which is mapped to host port 8500. It is not IPv6 enabled. This still means, I should be able to access it at localhost:8500. IPv6 ...
3
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2answers
5k views

Retrieve IPv6 address of website using terminal

Both the nslookup and host commands return IPv4 addresses only. How can i retrieve the IPv6 address of a website using the terminal? (I have googled around, unfortunately I couldn't find anything ...
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1answer
321 views

According to socket statistics Apache listens only on IPv6, but actually serves IPv4 as well

ss -lnp in server shows following information: # ss -lnp Recv-Q Send-Q Local Address:Port ...
3
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1answer
735 views

What's ndisc_cache?

Suppose I want to use : $ ip ntable show dev eth0 inet arp_cache dev eth0 refcnt 4 reachable 20744 base_reachable 30000 retrans 1000 gc_stale 60000 delay_probe 5000 queue 31 ...
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2answers
101 views

Execute Perl commands from a specific IP?

I have a Debian Jessie 8 server with three unique IPv4 IPs. I connect to the server from Windows 7 via Putty. I can open three Putty windows using each of the three IPs. I am trying to execute a Perl ...
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1answer
6k views

NAT box with multiple internal and external interfaces

Similar questions have been asked before but my setup is a little different and the solutions to those questions are not working. A have a CentOS 6 server running iptables with 5 interfaces: eth0: ...
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0answers
2k views

Force IPv4 over IPv6 only for certain addresses

I'm currently running Debian 8 and I'm trying to force applications like Google Chrome to use IPv4 over IPv6 only for certain sites. My ISP natively offers IPv6 and it's amazing on all websites that ...
2
votes
2answers
667 views

How does Debian select or prioritize IPv4 and IPv6 connections?

I'm going to explain my question with an example. I have two servers, A and B, both runs Debian 7.8, both have dual-stack connection to the Internet (I don't know if it matters but they even have the ...
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1answer
2k views

IPv4 broadcast routing in Linux

I have a server with three network interfaces- loopback interface lo and two physical network interfaces eth0 and eth1: 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN ...
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0answers
571 views

How does s_client turn ip6-localhost into 127.0.0.1?

When I use openssl s_client and ask it to connect to ip6-localhost it actually connects to 127.0.0.1 instead of ::1. This is what I see on both Ubuntu and Debian: $ strace -e connect openssl ...