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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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Linux: answer arp instead of the kernel?

Is it possible to answer ARP requests in user mode instead of inside the kernel? I can create a ETH_P_ARP socket but not sure if I can completely replace the kernel strategy at this level.
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1answer
29 views

How do I do traceroute/tracepath without any admin privileges?

Basically, I need to "trace a packet from my computer to the host" to diagnose a network issue and I do not need any fancy additional functionality. Redirect me to the right place if this is not the ...
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1answer
15 views

Linux equivalent of “no ICMP Unreachable” and “no ICMP Mask Reply”?

I have a Linux machine that is being used as a router. It has quagga installed and has ip forwarding enabled. It's forming an OSPF adjacency with a 3925 Cisco router. I'm being asked to ensure that ...
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2answers
37 views

Single iptable rule matching /32 and jump

We need to install a single iptables rule that match every source /32 user ip and jump to 'user chain': iptables -A INPUT -s "EVERY_USER-IP/32" -j "USER_IP/32_CHAIN" because we have hundreds of ...
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1answer
10 views

Cannot run getent command remotely

On my CentOS 7 machine, I am running this command: pssh -h rephosts -i "/bin/getent hosts sync.$(hostname) | awk '{ print $1 }'" but I am only getting my host ip (where i am executing this command) ...
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27 views

Is it possible to bond two bond two network connections and almost double single connection speeds?

I have two gigabit ethernet adaptors on my servers and my switch also supports 802.4ad and I tried several ways of configuring the bonding but so far I was not able to speed-up single connection ...
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0answers
26 views

Monitoring traffic by IP

I have machines with one interface eth0 with multiple different IP addresses attached to it (255) to be exact, interfaces look like this eth0:1, eth0:2 ...eth0:254. I want to monitor the traffic for ...
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4 views

Different AVAHI/Zerocinf Services for different VLANs

I couldn't find any reference in the man page for avahi so here is my question: Is there a possiblity to configure one service (printer) for only one VLAN and another service (printer) for another ...
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1answer
35 views

Duplication of UDP traffic to two ports on localhost

I need to redirect incoming UDP traffic to two services listening different UDP ports on localhost. I tried: iptables -t nat -I PREROUTING -p udp -d 10.11.12.13 --dport 22 -j DNAT --to-destination ...
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1answer
37 views

MySQL not allowing remote connections using Python3 mysql.connector on Raspbian-Stretch

I am trying to allow connections using mysql.connector from a specific machine to a MariaDB server, within the local network. Ideally, I would like to create an account limited to a single IP and DB. ...
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1answer
53 views

Intermittent http connection failure

We have two servers, ie host1.example.com host2.example.com One of these acts as the primary web server for our two main websites, example.com and example2.com. The other acts as a backup, which we ...
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1answer
24 views

Linux route policy based on tos returning wrong gateway

I have a simulated ad-hoc network running on Docker, using Ubuntu 16.04 as a base. I have a number of routing tables. The table in question, table 102, appears as: root@b22e0eafe06d:~# ip route show ...
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1answer
49 views

Unable to ssh server via ipv6

First: ipv4 works fine. So I got the following setup: (Server is an Arch Linux OS running as VM) EDIT Added a rule ACCEPT tcp ::/0 ::/0 tcp dpt:22 which ...
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1answer
61 views

Received empty response from Zabbix Agent at [X.X.X.X]. Assuming that agent dropped connection because of access permissions

I have a Zabbix configuration problem here in the company a few days ago. I'm having this error on the hosts page in the Settings portion. I have already done several tests, being: Agent and Server ...
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1answer
32 views

How to prevent a Port from being used while a service restart

I'm using Ubuntu 16.04 servers. Each server hosts multiple services. Sometimes, when a service is restarted, it fails to bind to the port and says that the port is already in used. Indeed, some ...
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0answers
20 views

Can't access modem settings page (CBN ch6541e)

I'm using CBN ch6541e modem and I can't access the settings page. The internet was slow so I decided to try to reset the settings to factory values (I was holding reset button for 10 seconds until ...
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0answers
23 views

NIC teaming issue on CentOS7

I have team interface with only one physical NIC em1 attached. Then I try to add another NIC em2 to team with following command: teamdctl team0 port add em2 After adding second NIC team interface ...
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0answers
41 views

Transparent LAN service on Linux

I need to implement a VLAN based transparent LAN service on Linux. Meaning I need to take configured VLAN and forward it directly to the specified port (all broadcast/multicast and unicast packets). ...
1
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1answer
24 views

How to configure iptables to pass data from net interface to bridge?

I am building an openstack all-in-one environment in a CentOS7.4 machine. For some reason I have only one network interface(eth0) and one ip address, so I created a linux bridge(br0), and forwarded ...
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0answers
16 views

What does gc-interval in named sets actually do?

I'm testing out named sets in my nftables ruleset but I can't find any explanation of what the gc-interval parameter actually does. The documentation simply states: Garbage collection interval, ...
2
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2answers
29 views

Nginx load balancing as gateway (without SNAT)

I'm trying to configure Nginx as last-resort backup for F5-BIG-IP and I'm not sure if it's possible to configure it to behave similarly to F5 in terms of traffic handling? F5 is currently deployed as ...
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0answers
38 views

Cannot ping my routers after interfaces configuration

I would like to make the following topology. , R1 / \ R2 R3 \ / R4 Where R1, R2, R3, and R4 are Cisco CSR 1000V routers. R1 IP-address = 3.16.176.197 Interface IP-...
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0answers
33 views

svn: E000110: Error running context: Connection timed out

I am having an SVN server in India location. I have totally 6 client six servers in the different country. One of my Edge server facing an svn: E000110: Error running context: Connection timed out in ...
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1answer
28 views

How to expose a port+url visible to one machine to another

Essentially I have 3 machines: A, B and C A can see B (and vice versa) and B can see C (and vice versa). A can't see C (not part of the same network). I have access to A and B. Meaning I can start ...
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0answers
31 views

Forwarding Fragments with IPTables / FirewallD

I have a linux (openSuse Leap 15.0) computer that's connected to a cable modem using PPoE (hopefully not relevant to this. EDIT the ppp0 interface has an mtu of 1492 but the eth0 interface it is "...
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0answers
43 views

samba 4 ad with bind dlz with 2 network interface

i have a Samba4 AD server with BIND_DLZ working. My server has 2 network interfaces, one for the administration and another to clients. The problem is that i need that samba listen on both ...
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0answers
6 views

Connecting to a HyperV Guest from Host [migrated]

I’m wondering if it is possible to connect to a HyperV Guest from the Host. The guest is a Linux machine and the Host is a Win 10 Pro. Specifically, I cannot ssh to the Linux Guest from the Host. I ...
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0answers
23 views

How can I advertise routes in BIRD?

I am trying to advertise some routes from my bird server to my Cisco router, I already have a neighbor relationship with my Cisco router, but I am not learning the advertisement networks from bird. My ...
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0answers
39 views

Netplan with 2 NICs each connected to a different gateway

Anyone familiar enough with Netplan? I'm a bit confused on how to configure an Ubuntu 18 server with two NICS using Netplan. Each NIC is on a separate subnet. They are directly connected to separate ...
1
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1answer
58 views

Static MAC address for cluster nodes on AWS

There are some scientific computations to be run. They use a software module, which license is tied to a MAC address. On AWS I created ENI (Elastic Network Interface). I tie it to EC2 instances of my ...
1
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1answer
67 views

Very poor network performance in HyperV connections routed via a VirtualSwitch vEthernet NAT interface

I have a ubuntu 16.04 LTS guest VM running inside HyperV on Win10 pro v1803 (build 17134.345). The guest does have internet connectivity through a Virtual Ethernet Adapter NAT on the host, but ...
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1answer
28 views

Nginx image display issue after optimization

I made some optimizations using gtmetrix to improve web site performance. Like enabling gzip compression etc.. When I try to test site using online services like browserling.com images are not ...
2
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1answer
119 views

How to configure iptables for a dial-up VPN with OpenVPN and two interfaces?

I have an AWS EC2 instance, running Amazon Linux, that has two Elastic Network Interfaces (ENIs) attached: eth0 and eth1. I am connecting to the public IP on eth0. Everything works great, except I ...
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2answers
448 views

How do increase data transfer rate between my VMs

I saw lots of article,but didn't answer my question. My server use VMware vSphere Hypervisor. There are 20 virtual machines in my server. VM operating system : centos7 I already change my vSwitch ...
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1answer
66 views

What does rx_csum_offload_errors mean?

I see too many rx_csum_offload_errors on ethtool output and it constantly increases. What is the reason of these errors and how can I fix it? # ethtool -S enp12s0f0 | grep error rx_errors: 0 ...
2
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1answer
38 views

Why does ACCEPT all for all destinations in iptables not allow port 8445?

I have a test server which has the following IPtables configuration: [root@rhel64 /]# iptables --list Chain INPUT (policy ACCEPT) target prot opt source destination ACCEPT all -...
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1answer
43 views

Route internet to tun1 INSTEAD of tun0

I'm using a debian based desktop distro, but I imagine that is probably irrelevant. I have a very simple query that I can seem to find the answer to anywhere, probably because no one does this. I have ...
2
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1answer
89 views

OpenVPN: Addressing remote LANs

I've been trying to solve this problem for a while now, but to no avail. We basically have an OpenVPN server to which our end devices need to connect. Some of those devices can directly connect to the ...
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0answers
9 views

remove ncat rule or secure with bastic auth

I setted up this rule to make the docker api port available: nohup ncat -lknvp 2375 -c "ncat -U /var/run/docker.sock" & Now I need to remove it or to make it secure with basic auth for example? ...
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0answers
20 views

How virtualization affects Linux guest reports of CPU usage?

We have a Hyper-V guest with 4 virtual cores reporting 50% usage total among all the virtual cores. That is, this 50% is what atop and top report, with a complementary 350% of "idle". That means at ...
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0answers
23 views

Two sub bonding interfaces with different options on the same interfaces

I have two optical interfaces on server and I want to make two bond interfaces on mode active+standby with these physical interfaces. One physical interface must be serviced by vlan and be primary for ...
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0answers
41 views

Limit download and upload speed per user on CentOS7

I have CentOS7 box acting as gateway. I need to limit download and upload speed for each user to 10Mbps and after 2GB per day quota reduce speed to 2Mbps. This can be done with tc and iptables but I ...
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0answers
17 views

How to setup port-forwarding between docker cli and host machine? (Permission denied: publickey)

I'm inside a docker cli (via docker exec -it cli bash). And I need to host a simple development server (expressjs) in the container. For reasons of I dont want to get into, I cant create a dockerfile ...
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0answers
55 views

Certain network request errors only inside VMs

I have Proxmox 5.2 installed on NUC for over a month and everything work fine. In the recent days, I decided to create a new workstation VM machine, and noticed something strange. Certain network ...
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1answer
48 views

Custom resolv.conf file

Is there any way I can specify a custom resolv.conf file (instead of /etc/resolv.conf) in RedHat Linux, similar to specifying custom hosts file via export HOSTALIASES=~/my_hosts? I don't have root ...
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0answers
41 views

Configure public ipv6 address to kvm guest in macvtap network mode

Host(ubuntu16.04) has /64 ipv6 assigned to it and one ipv4 address. Trying to create a ubuntu virtual machine in macvtap network mode and assign a public ipv6. So I Created 'macvtap' network using ...
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0answers
72 views

Linux kernel 4.9 not responding to neighbour solicitation

I have this small network where Linux kernel 4.9 acts as a v6 router. There are two other servers connected to this router and both have ipv6 address configured on interfaces connecting to this router....
4
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1answer
172 views

Adding a whole IPv6 /64 block to a server using Netplan

I have read Adding a whole IPv6 /64 block to an network interface on debian We want to make use of the AnyIP feature to add a whole IPv6 /64 subnet block to a web hosting server but using Netplan ...
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0answers
28 views

sudden lost of access to esxi vSphere network

Our lab setup consists of a vSphere Esxi server hosting some VMs. In front of VMs exists a pfSense router VM. All VMs are getting connectivity from router and additionally a openVPN server is set in ...
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0answers
26 views

multiple networks in keepalived configuration

I have two router(lxc containers) seated in the distribution layer of my network and I want to implement HA for them. The routers have 114 network interfaces and I want that they share a virtual ip ...