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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Wireguard with multiple local subnets using iptables
I'm trying to allow multiple local subnets when using a wireguard VPN. Below is the iptables config from my wireguard config file.
I'm assuming I have to write this in a different way, but I have no ...
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DDNS DuckDNS For Static IP Address Issue
I've built a web server with my pi using the LEMP stack server (Nginx as my main web server), and I already have my own domain at Godaddy. I'm just wondering if I need to add any additional DNS ...
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RouterOS 7: Configure the Wireguard server to support connections by different WAN access IP
RouterOS 7 router with two WAN ports, WAN2 and WAN3(I can access Winbox with both of these WAN IPs without any issues), and set up a Wireguard (WG) service. I can successfully connect to WG by the ...
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LDAP config on Openfiler SAN
We have a production Openfiler SAN (vs 2.99) that has been using Windows Authentication to grab groups for file permissions for 5 or 6 years now (configured via the GUI). It's pointing to the then, ...
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Is it possible to configure a Linux/Ubuntu computer to be network silent?
I'm testing a customized network device using a Ubuntu computer from which I send network packets and check the actions on the network device. I'd like to only send over the packet I want, but since ...
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Filter packets with iptables on a tap interface
I'm trying to write firewall rules to prevent a guest machine from accessing the internet.
The server (Ubuntu server 22.0, using KVM) has a physical connection (enp34s0), which is connected to the ...
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Is it possible to setup a VPN that passes multiple ports through a single port tunnel?
I am looking to set up a VPN (possibly OpenVPN) to allow a computer connected to the internet through a restricted university network to connect to the wider internet through my home network.
My ...
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How do I see the amount of bandwidth used during the execution of a program?
When executing a program, from a shell, how do I see the total amount of network bandwidth used by that program?
I am thinking of something similar to time, but for bandwidth.
petur@petur:~$ time ...
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Raising priority of network interface interrupts on Ubuntu 22 low latency kernel 5.15
I am running Ubuntu 18 on several servers with the low latency kernel.
Previously I have used chrt to raise the priority of interrupt threads for the interrupts related to a specific network interface....
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Debian + Strongswan: does not pass traffic from the Internet to the tunnel
I'm trying to setup a remote VPN server to access the internet from my home PC. It is on a leased AWS VPS, with Debian and Strongswan. It is meant to receive my traffic via the tunnel, forward it to ...
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Why can I not connect to ipvlan l2 and macvlan networks on docker?
Macvlan
I have tried it on several computers and VM's.
I have tried activating promiscuous mode in all relevant computers and VM's. Related thread by me on Super User.
I have tried wireless and wired ...
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Recover network connection from ubuntu 22.04 console after crash
my perfectly operational ubuntu machine with nvidia GTX 1650 crashed when I tried sudo apt-get remove python3
Now it boots directly into terminal. When I run startx it shows a graphical window with ...
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Loading an eBPF program causes IRQ affinities to be modified - (ixgbe driver)
I am working on an eBPF/XDP application running on a server with Intel 10G X550T NICs, using the ixgbe driver.
I need precise control over how the work is distributed between cores, so I'm disabling ...
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Network card not providing maximum throughput Ubuntu server
I have a server in OVH.
My server is able to deliver 1gbps, I make sure it's actually can deliver this in their rescue mode.
When the system is up to the Ubuntu layer, the performance drops to ~...
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How can I setup Nginx with a transparent socket?
Similarly to this Cloudflare blog post, I am trying to setup Nginx with a transparent socket (with the IP_TRANSPARENT socket option). I want to do this to implement a reverse TCP proxy that ...
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A gateway of 0.0.0.0 gets added in my linux machine after I assign a static IP and static gateway
I am assigning static IP address on a Linux module (custom Yocto Distribution on TI AM3359 custom hardware) using the ifconfig command.
sudo ifconfig eth1 10.11.3.80 netmask 255.255.248.0
sudo route ...
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Routing 2 public IP ranges on 2 bridges
I've set up a new Proxmox 8 server, and I'm struggling to get my networking set up correctly. A normal bridge interface with a single IP range is easy enough, but I can't seem to get my 2 IP ranges to ...
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Is it safe to use a Linux GRE tunnel with remote IP 0.0.0.0?
I have plenty of remote servers that have GRE tunnels to a single central server. Tunnel traffic is only from the remote servers to the central server.
So for 50 remote servers, I usually have 50 GRE ...
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Changing KVM VM listening on 5901 to some other port
OK this is rather silly, but real problem.
vncserver keeps binding on 5902 port. That is because qemu is listening on 5900 and 5901:
% netstat -lntup
Active Internet connections (only servers)
Proto ...
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adding a static route with nmcli to virtual bridge breaks kvm networking but
I have a virtual bridge br0 created with nmcli, with a physical ethernet interface attached to it
the bridge device is the used with kvn virt-manager virtual machines.
They get a static IP address.
...
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how to setup socks5 proxy server on centos9 for network access behind firewall?
I need a socks proxy on centos 9, to access services from an (internal) network behind a firewall.
It should be a socks 5 proxy (dynamic port forwarding) that can only be used by the configured ssh ...
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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 ...
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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 ...
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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 ...
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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:
...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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:...
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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 ...
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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 ...
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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 ...
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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 ...
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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-...
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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 ...
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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 ...
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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 ...
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