Questions tagged [linux-networking]

Linux Networking refers to any networking function performed by a server running Linux. A Linux server operating as a router or firewall are the most common applications.

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Tap interface injected packet not received at user appllication

I have written an application using AF_XDP sockets, currently all packets are received on the interface are received by the Af_XDP application. The application filters packet of specific port number ...
Gour DEV's user avatar
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Best approach for deploying code to servers behind a gateway

I am attempting to adjust my deployment scripts to access a server behind a newly established gateway that I've configured. The gateway currently is accepting traffic from the internet correctly and ...
Rohit Keshwani's user avatar
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Duplicate all outgoing IP packets

We're having an issue with our ISP where 75% of our outgoing IP packets are lost to the ether. Incoming packets are totally unaffected, and we assume we're not being throttled because we can send ...
steventrouble's user avatar
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ipv6 : same /64 prefix across multiple physical subnets / interfaces - in Linux

I'm trying to figure out how to configure a single ipv6 /64 prefix that need to be routed across several different physical subnets interfaces. The problem illustration is like this: ...
user4433437's user avatar
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nftables netdev rewrite - what I'm doing wrong?

[EDITED] I'm receiving on physical interface ERSPAN-encapsulated traffic and need to process just a small part of it. In order to do this, I'm decapsulating traffic on local tunnel interface: ip link ...
Volodymyr Litovka's user avatar
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Routing traffic between A and C using A-B wireguard's network

I'm having some difficulties setting up a routing between 3 nodes. Here's the situation: A, B and R are wireguard (wg0) peers R is a public hub (vpn.example.com) with IP 172.0.0.1 A is a peer ...
ARDVL's user avatar
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nftables masquerading is not working

I've a laptop (172.16.0.2) and a desktop PC (172.16.0.1). The phone is connected to the PC in USB modem mode, and it appears as the enp5s0f3u1 interface. I've set up masquerading through nftables so ...
BlitDev's user avatar
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How to make IpTable Rules immutable in linux

I work on Linux and want to add rules to iptable. I want these rules to be immutable anyway (either changed or deleted). What should I do? Note that for me the rules that are running and kept in ...
amirsalimi's user avatar
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Alma 9 Unable to make the interface DOWN at boot

OS: Alma-9.2 I am trying to disable an interface (ens224) at boot using the nmcli tool. I tried using the option nmcli connection modify ens224 connection.autoconnect no,nmcli connection down id ...
Vishnu's user avatar
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Linux bridge not forwarding traffic after changing bridge ports

Problem: after changing bridge-ports value of a network interface, all networking on that IP stops working. Base system is Proxmox VE 7.4, based on Debian Bullseye. Background: I have a Proxmox VE ...
Lukasz's user avatar
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Route outgoing packets from VM to GRE tunnel from which income packets came from? (TCP flows)

We have a network infrastructure with Anycast IPs on edge servers in multiple countries, those servers encapsulate traffic in GRE tunnels to endpoint nodes with virtual machines Currently we route all ...
Oleg Pawson's user avatar
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Unable to create a Linux bridge with a VLAN interface on Fedora

I'm trying to set up a Linux bridge that includes a VLAN interface on my Fedora system. My goal is to use this bridge with virt-manager to create multiple VMs, each with an interface in the bridge ...
a-kodez's user avatar
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Iptables blocks loopback interface but why?

I am having trouble understanding why iptables is blocking my loopback interface traffic. Here is the scenario: I set the default policy of the INPUT chain to DROP. I allow traffic to port 8080. My ...
Bongo's user avatar
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Apache virtual host for server in local network

How to create a virtual host in Apache for a server on a local network so that it can be accessed via the Internet. I have server with statick ip and working site on em (first.mysite.org) , but i ...
TechWizard's user avatar
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Martian packet with ARP broadcast traffic

Server nodes keep getting ARP broadcast traffic and becoming martian packets due to assymatric routing. I was known that when strict filtering is enabled with net.ipv4.conf.eth0.rp_filter = 1, the ...
Rama's user avatar
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Martian source with an IP with another MAC

Seeing a lot of martian logs: May 15 08:30:27 prd-srvr1 kernel: [789192.798073] IPv4: martian source 192.168.0.200 from 10.0.0.115, on dev eth0 May 15 08:30:27 prd-srvr1 kernel: [789192.798095] ll ...
Rama's user avatar
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"Destination Port Unreachable" only on secondary IP of VM

An vmware VM is assigned two IPs. We can only ping one of the two IPs from VMs on the same network. 2: ens160: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen ...
Vladimir's user avatar
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Redirect Traffic on OVS switch

I have below topology on mininet: Host1:10.0.0.1/24 mac :aa:00:00:00:00:01 Host2:10.0.0.2/24 mac :aa:00:00:00:00:02 Host3:10.0.0.3/24 mac :aa:00:00:00:00:03 I want to redirect traffic as below: When ...
dyvesh mahadea's user avatar
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2 answers
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Unbalanced RX data when using network bonding in mode-4

We use a dual network card server with bond in 802.3ad mode. # cat /proc/net/bonding/bond0 Ethernet Channel Bonding Driver: v5.14.21 Bonding Mode: IEEE 802.3ad Dynamic link aggregation Transmit Hash ...
Frontier_Setter's user avatar
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How ARP (address resolution protocol) works with ethernet bonding?

We use a dual network card server with bond in 802.3ad mode. The outgoing bandwidth on both network cards is balanced, but the incoming bandwidth is concentrated on one network card. This issue is ...
Frontier_Setter's user avatar
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1 answer
302 views

Could not bind to address no listening sockets available

RockyLinux 9. On reboot Apache fails to start with the message Jul 21 10:53:13 cl httpd[877]: (99)Cannot assign requested address: AH00072: make_sock: could not bind to address 1.2.3.4:80 Jul 21 10:53:...
Clodoaldo's user avatar
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Assigning a fixed IP to a VM on Alma Linux

I have a Alma Linux 9 host with two IP addresses. I want assign one IP to the host (This is already done) and the second one to a Ubuntu VM. What's the best way to do this? I've set up the VM through ...
Aaron Dewes's user avatar
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Getting "has no address records (A or AAAA)" error when running named-checkzone

I am currently trying to build my own home lab for the first time, and as a newbie it’s been a bit confusing. For the past few days, I have been working on configuring an internal DNS server, and ...
DiamondFeather's user avatar
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Fresh install of Rocky 8, networking is not working correctly

I am "upgrading" a server from CentOS 7 to Rocky 8. This server is a 1U Supermicro SYS-1029U-TRT, works as part of an HPC, and has two Ethernet and one Infiniband networking interfaces. One ...
Chris Woelkers's user avatar
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150 views

iptables: Only allow one IP address when rules are updated by other tools

I'm learning about iptables and I want to set up a GNS3 (network emulation) host on a public IP and limit the access to only one IP address. This one IP address should be able to connect with all ...
itsamemarkus's user avatar
1 vote
1 answer
316 views

Libvirt - UDP not working between host and VM

Host: 192.168.1.144/24 VMs(routed) network: 192.168.122.0/24 I have VMs connected to libvirt's routed network. <network> <name>routed-122</name> <uuid>86ca64a6-7fea-4cf8-...
chupnik's user avatar
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Connecting 2 Virtualbox VMs to Open vSwitch running on another Virtualbox VM

I have 3 Ubuntu 22.04 VMs created using Virtualbox. My host machine is Windows 10. One of them is running 5G core emulator, and the other one is running UEransim. I was able to connect UE to 5G ...
Michał Ryba's user avatar
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577 views

iptable rule for an IP address with "any" subnet mask

I have a requirement to add an iptable rule for lets say src IP 10.10.10.20/any dest IP any. iptables -t filter -A FORWARD_0_IN -p all --ipv4 --source 10.10.10.1/any --destination 10.10.10.2/any -j ...
RootPhoenix's user avatar
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3 answers
365 views

Is 'sudoer' a must for 'ip' command? Anyway to get around it?

I recently came across a High Availability scenario that the maintenance program needs to bind a virtual IP to the server it sits and then broadcast it over the network. To do so it runs ip and arp ...
George Y's user avatar
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How to make secondary IP routable

I am trying to assign a secondary IP to my primary interface. I added the IP to my eth0 interface ip addr add 172.20.14.253/21 dev eth0 $ ip a show dev eth0 2: eth0: <BROADCAST,MULTICAST,UP,...
Hussain Nagri's user avatar
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288 views

OVS switch and Tap interface- Connecting two vm using tap interface-ubuntu

I want to connect 2 VM together using tap interface on Ubuntu. VM2 will connect to VM1 by a tap interface on VM1. I will use OVS switch to forward traffic from VM1 to VM2. Scenario: Router from ISP ...
dyvesh mahadea's user avatar
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'iw dev XYZ interface add' is not using the provided 'addr' option

The title says it all. I am running: sudo iw dev wlp2s0 interface add my_interface type managed addr 12:34:56:78:9a:bc Then, upon checking iw my_interface info I see a completely different address.
onlycparra's user avatar
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See per-VM network usage in Xen Hypervisor (nethogs)

How can I see my network utilization per-VM in realtime in Xen? On a system, I can see the real-time, per-process utilization of my network using nethogs. On my Xen system, there's xentop, but (even ...
Michael Altfield's user avatar
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91 views

UFW SSH deny rule not working

TLDR: I'm trying to block SSH connections to a server; the server itself is connected to a ubuntu router with UFW on it, but external SSH connections to the server aren't getting denied, UFW doesn't ...
rob_qwerty's user avatar
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1 answer
130 views

Winbind and AD: Local users with identical AD usernames

we successfully got Samba up and running with Winbind on our openLeap 15.4. The Linux server is a member of the Windows domain. Due to a user with identical name in AD as well as locally on the Linux ...
parcival39's user avatar
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0 answers
475 views

Amazon Linux 2023: systcl kernel parameters - network - hardening and tuning review

We are in the process of transitioning to Amazon Gnu/Linux 2023, and during the course of this migration, I came across some Ansible code that modifies kernel parameters. I would greatly appreciate it ...
Ygor Thomaz's user avatar
1 vote
0 answers
110 views

Where to put VLAN interface

I have a Proxmox VE 7.4 installed on a server (that's debian 11-based distro). On this server I have 2 x 1 Gbps network interfaces. On top of them i have Linux bond (LACP mode, but probably ...
Lucius's user avatar
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Edgeline EL8000 not able to process provider network traffic with OpenStack

I am currently trying to install OpenStack on an Edgeline EL8000 that has 4 server blades. I have OpenStack running and configured but I am unable to create a provider flat network on my home network ...
Sean Rahman's user avatar
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2 answers
359 views

How does GRE interface route packet to remote endpoint

I have the following topology which I configured to run a GRE tunnel between my Desktop and the wireless router. On the PC: ip link add l2gre0 type gretap remote 192.168.0.103 local 192.168.0.10 On ...
Haswell's user avatar
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Is it possible to bypass linux bridge device and assign linux vlan directly to bridge member on proxmox (Debian)?

I came up with the following situation. We have a Proxmox node with a 40gb Mellanox QSFP+ card connected to switch. The 40gb interface is added as a slave to vlan aware linux bridge. To that bridge ...
The amateur programmer's user avatar
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0 answers
103 views

Unable to Ping Guest VM's of Nested KVM on Vmware Workstation

I have installed KVM (RHEL 8) on VMware Workstation and created a Guest OS with CentOS 8. I have created a Bridge Network (slave: ens160) and assigned it to the Guest VM. The Guest VM has received an ...
UME's user avatar
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990 views

Calico : Virtual Network Interfaces not created by calico

I had been using calico-policy-only (v 3.22) mode with kubernetes 1.24.1 in my worker nodes. Recently worker nodes were upgraded to 1.25.4 , so for compatibility we had to upgrade calico as well to ...
devcodes's user avatar
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-1 votes
1 answer
410 views

Making all Linux network interface (bridged) in a qemu VM use dhcp

I have a small application which takes in kernel code, and spins up VMs. I've been using this for kernel development. It is helpful and very fast when I want to spin up VMs with different kernel codes....
Haris's user avatar
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1 answer
792 views

How to forward (inside a container) requests from 0.0.0.0 to 127.0.0.1

Looking for a solution on how to forward the requests from 0.0.0.0:9222 --> 127.0.0.1:9222 inside a container I am using a docker container with google-chrome-stable installed for running visual ...
Svenv's user avatar
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1 vote
2 answers
382 views

Can't PING or nslookup outside the LAN

Ubuntu 18.04 cannot PING or nslookup outside the LAN. When I do nslookup www.google.comit hangs for a while and returns ;; connection timed out; no servers could be reached. I cannot PING www.google....
BioRod's user avatar
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Virtual machines not working with 802.1X - Linux Bridge

I am experimenting 802.1X in my home lab. I have most stuff working but one problem I have is with virtual machines not being able to authentication onto the network using 802.1X. There is very little ...
Tipex's user avatar
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587 views

Unable to make bridge interface UP state

I am just learning networking, Pardon if my question does not give all details, I can provide if needed. I am trying to learn network namespaces in Linux. I have created two namespaces red and blue ip ...
Raheel's user avatar
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50 views

Configure network stack to consume data from TAP device, so that application can operate as if the data was intended to it

I have two devices communicating, A and B over udp. In between there is a tap device, where C is connected. In order for C to be able to receive the traffic it needs to set the same ip and mac address ...
Aleksandarf's user avatar
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0 answers
186 views

How to do Dpdk binding with bonding interface

In server1(ubuntu 22.04.2), I have 2 physical 10G port : port1 & port2 and their respective interfaces. Now I have another interface named bond0 which has 2 slave interfaces (the 2 physical ports ...
Nafiul Alam Fuji's user avatar
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1 answer
313 views

IPTABLES no internet access from lan with default FORWARD rule set to DROP

I'm trying to set up ubuntu server 22.04 (virtualized) as a router with one wan interface (ens18) and several lan interfaces ens19:ens23 & ens1. Here is what im trying to achieve: allow ens19:...
INDIVISUM's user avatar

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