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Questions tagged [networking]

Managing and using network connectivity on a unix system

18
votes
7answers
42k views

Is there a way to set network proxy system-wide?

If I want to have GNOME applications (as well as Firefox and Chrome) access the network through a proxy, I need only use gnome-network-properties (a nice and simple GUI I must say). For other apps (e....
0
votes
1answer
32 views

Netcat listens on a wrong port

When I run the command nc -l -p 443 it starts listening but when I try connecting to it it fails. A few hours later I tried with verbose mode nc -lvp 443 and it printed out listening on [any] 2443. ...
1
vote
1answer
3k views

Wi-Fi troubles on Ubuntu 16.04, using Qualcomm Atheros in a Lenovo v510

I have a Lenovo v510, running Ubuntu 16.04, and I can't get wireless networking to work.  'Enable Wi-fi' has no effect, no networks show up.  Some commands that I've tried, and their corresponding ...
0
votes
1answer
28 views

Seeing dead process in nethogs?

nethogs is a very useful tool to see which process(es) send/receive lots of network traffic. But as soon as the process exits, on the next display refresh nethogs no longer displays the process. Is ...
4
votes
4answers
2k views

Is there any way to see how much data I sent via Internet?

A big German ISP (Telekom) recently decided to volume limit their DSL internet connection to 75GB per month. Now I would like to know how much I download / upload. I use Linux Mint 14 Nadia and I ...
0
votes
0answers
22 views

Creating Iptables rules for router in front of several servers

I'm trying to create a test environment for some software I've written and I'm running into issues with creating the right iptable rules. I have a router that the rules are being written too, and I ...
1
vote
2answers
2k views

Debian Stretch won't resolve hostname, but IP works

I have configured Stretch networking for eth0 (it picked ens3), after setting: GRUB_CMDLINE_LINUX="net.ifnames=0 biosdevname=0" grub-mkconfig -o /boot/grub/grub.cfg reboot so now I have: >: cat /...
0
votes
1answer
686 views

Set SO_TCP_NODELAY (disabling the Nagle Algorithm)

As I know we have a socket option SO_TCP_NODELAY to disable Nagle Algorithm, and I found it is implemented in TCP/IP stack at https://elixir.bootlin.com/linux/v4.4.90/source/net/ipv4/tcp.c#L2401 . ...
10
votes
2answers
4k views

What's the “right way” to effect changes in /etc/resolv.conf with /etc/resolv.conf.d in place?

I the old days, resolv.conf was static and you edited it yourself. Later on, the DHCP client would rewrite it, using some static entries and what it got from the DHCP lease. These days, some ...
0
votes
0answers
27 views

My laptop doesn't detect my wi-fi

Recently my old dell laptop started to work very slowly, so I decided to install linux on it. I choosed debian (cause i like it). everything was ok, i installed drivers, programs etc. but when I tried ...
-1
votes
1answer
42 views

Packet loss on linux but NOT in a vm running on the same machine!

Something seems to be very wrong with my network stack right now. Not sure where to start debugging. I have Ubuntu 18.10 running a windows 10 VM with QEMU/KVM. The network is bridged together so both ...
0
votes
1answer
3k views

Centos 7: No Wifi Adapter found

I have dual booted centos 7 with Windows 10. Once centos 7 setup finished, no wifi connection was available. In the "settings > Wifi", I see a message saying "No wifi adapter found". My wifi adapter ...
1
vote
0answers
41 views

3 IP on one ethernet that not exist!

when i run "ip -d addr" show 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 promiscuity 0 inet 127.0.0.1/8 scope host ...
0
votes
0answers
24 views

Debian 10 wifi connection with heavy delay (but no package loss)

$ PING www.debian.org(klecker-misc.debian.org (2001:67c:2564:a119::148:14)) 56 data bytes 64 bytes from klecker-misc.debian.org (2001:67c:2564:a119::148:14): icmp_seq=1 ttl=56 time=19481 ms 64 bytes ...
3
votes
1answer
1k views

Sane can't see Samsung CLX-3305W network scanner in Ubuntu 14.04LTS

I've installed a new Samsung CLX-3305W multifunction printer/scanner a couple of weeks ago on a dual boot system with W7 on one physical drive and Ubuntu 14.04 64-bit on a separate drive. The printer ...
2
votes
1answer
7k views

Network UNCLAIMED - Unable to access internet

My Kubuntu was working well until I think a day ago, and suddenly I don't have access to Wi-Fi. I've tried turning on the connection via the Connection editor but the box was grayed out. After looking ...
0
votes
0answers
18 views

Can't connect to router

I have a problem with my fresh installed Fedora 30. I have internet access via LAN, but I can't ping my router or any website. Also no DNS server like Google's 8.8.8.8. If I look on my profile, my IP ...
4
votes
2answers
9k views

Unable to connect to any wifi with NetworkManager due to error: Secrets were required, but not provided

Using NetworkManager on Arch Linux on a MacBookPro14,3, I am unable to connect to any wireless network. I've tried connecting to a number of different WiFi networks (home, mobile hotspot, work) all ...
1
vote
1answer
33 views

Default TCP KeepAlive settings

The TCP KeepAlive (socket option SO_KEEPALIVE) is governed by three options—time after which the mechanism triggers, probing interval, and number of failed probes after which the connecting is ...
1
vote
1answer
10 views

How to cleanup network interfaces after an LXC container crashes on startup

Today I modified an LXC container to add an extra "bind mount", but forgot to create the mount directory in the container root filesystem. As a result the container startup failed, and left the ...
1
vote
1answer
31 views

Is it possible to talk to a different subnet through another device?

I am trying to adjust the networking on a system so that two subnets can talk to each (ping) other via a device. Setup looks as follows: (192.168.1.128) (172.16.248.223) Router <------&...
3
votes
1answer
144 views

How to connect to ieee8021x Network using connman

Connect to my private WPA2 Wifi with connman works like a charm (followed this instructions). But when I try to connect to ieee8021x Network, i always get this error: Error /net/connman/service/...
0
votes
0answers
17 views

Swapping source and destination mac address cause packet to not be sent

I am currently testing a scenario using Python and scapy. When I send a packet which has a src mac of 80:CA:0E:BD:60:3B and destination mac of 82:DA:0E:BD:60:3A, the packet is sent out the specified ...
0
votes
1answer
1k views

Install brctl for OpenWrt - which package?

I'm getting an error in OpenWRT Attitude Adjustment that says: -ash: brctl: not found when I run brctl addif br-lan mesh0 I tried: opkg update opkg install brctl But I got this error: Unknown ...
0
votes
1answer
645 views

Unable to load SFP+

I am using CentOS7 7.5.1804. I have a Intel 82599 based 10gig SFP+ card. When I try my SFP's I get: failed to load because an unsupported SFP+ or QSFP module type was detected. I tried everything I ...
0
votes
2answers
943 views

KVM Linux guest cannot get network address

I use libvirt-manager to manager my VMs. I create a new VM, and a default virtual network, which uses NAT. virsh net-edit default gives me: <network> <name>default</name> <...
1
vote
2answers
56 views

netstat lists ip addresses not found in “ip address list” or ifconfig--what's going on?

My understanding was thatsudo netstat -tlupn gives me all the addresses/ports that have processes listening and that ip address list or ifconfig (though I guess the latter is deprecated) would give ...
0
votes
0answers
24 views

Alfa Awus036ach causes password prompt loop, won't connect

I want to use my Alfa Awus 036ach wireless card in my Debian 9 (stretch) system.  The system is dual boot; the other OS Kali Linux, where the cards works properly, so I assume this is not a hardware ...
72
votes
8answers
103k views

Simple way to create a tunnel from one local port to another?

I have a development server, which is only accessible from 127.0.0.1:8000, not 192.168.1.x:8000. As a quick hack, is there a way to set up something to listen on another port (say, 8001) so that from ...
0
votes
1answer
49 views

netcat no route to host on port 80 but not on 22

I am in a vpn into another country. I have a VM there that I can reach via ssh. It's awfully slow but it works. Netcat to port 22 also shows open port and reports with openSSH banner. So the routing ...
3
votes
1answer
55 views

OpenBSD Supported Hardware

I've recently installed OpenBSD on my Lenovo Ideapad 510s-14ISK. Unfortunately, it seems that my current network card (Qualcomm Atheros NFA435 QCA9377-5 / NFA 344 QCA6174 WiFi 802.11ac 1x1 + BT) is ...
2
votes
2answers
8k views

How to allow guest OS to access Internet in qemu?

I've created a Windows XP image and I'm booting it with qemu. When using "user mode networking" via -net user, my guest os (windows xp) gets the 10.0.2.15 IP assigned and I can ping 10.0.2.2 so ...
3
votes
3answers
450 views

Backup and restore of Centos network interfaces

I have a server running Centos 7 which needs to be rebooted to upgrade some software. Some of the physical NICs have around 5-10 VLAN interfaces each. They're subject to change on a weekly/monthly ...
2
votes
0answers
175 views

Fedora 30 causes problem with MTU bug

The issue After installing Fedora 30 (KDE) on my laptop my router would crash shortly after I connected to it. This happened both when I connected through wired Ethernet and Wi-Fi. Fortunately, the ...
3
votes
0answers
51 views

Why is my client getting two IP addresses when connecting to WiFi?

A sub-question: why is my client requesting a specific IP address without a dhclient running? I have two access points. One is serving up two SSIDs, the other just one SSID. When I connect to the two-...
0
votes
1answer
38 views

How Can I Make My KVM guest VM Accessible from the External Network?

I am creating a kvm setup for POC. KVM Host IP range: 172.21.158.0/24 KVM GUEST VM Range: 172.21.183.0/24 default virtual network with NAT forwarding :192.168.100.0/24 below are the guest vm NIC ...
8
votes
2answers
21k views

recvmsg returns 'EAGAIN (Resource temporarily unavailable)'

After a recent server move, we are troubleshooting this wierd issue of one of the server losing n/w connectivity for no apparent reason and regaining the connectivity in a few seconds or minutes. ...
0
votes
1answer
5k views

How to route between interfaces

I have the following setup: (192.168.4.1) Device A <-------> device B <-------> Device C (192.168.5.84) (192.168.5.1) (192....
0
votes
1answer
12 views

RHEL 7 multi-user.target disables Wi-Fi

Every time I set my system target to multi-user.target, I lose connection to Wi-Fi and thus can't control my machine via ssh after a reboot, and when I go to /etc/sysconfig/network-scripts, I don't ...
0
votes
1answer
347 views

Locating Drivers for Intel AX200 Wireless on 5.1 Kernel

I recently purchased a new laptop which features an Intel Wireless-AX200 Networking device for Wi-Fi and Bluetooth connectivity. I installed elementary OS 5.0 "Juno" along with the latest stable linux ...
0
votes
0answers
20 views

Linux seperate a network into two using MACVLAN - one for internet, one for internal communication

I have two minimal embedded devices that has ip, ipconfig, nat, etc support. The embedded devices share network over USB. I want to configure each board so that they have two seperate interfaces, ...
1
vote
0answers
30 views

wol: MagicPacket received; machine not waking up

As a follow up to this question. I've confirmed and double-checked that the MagicPacket is not filtered that the ethernet-card in the machine is powered after shutdown that the MagicPacket is ...
1
vote
1answer
27 views

No internet connection with some routers

On my laptop I run Debian Testing with no Desktop Environment. I manage the Wifi connections by adding entries to /etc/network/interfaces and then running /etc/init.d/networking restart. dmesg says: ...
0
votes
0answers
38 views

jessie: wake-on-lan -> ok; stretch: wake-on-lan -> broken

I upgraded a headless machine (with openmediavault) from jessie to stretch and after that wake-on-lan stopped working. I ran down the following checks: >ethtool eth0 ------------------- Supports ...
0
votes
1answer
33 views

How to set an IP from a specific range with dhcp?

I want to set a IP to my Debian machine using dhcp but I only want to select that IP from a specific range . For example, my net is 10.0.100.0/24 and the range has to be from 10.0.100.90 to 10.0.100....
5
votes
1answer
110 views

RHCE Study Lab: KVM networking and ping issues

I'm trying to setup an RHCE study lab per Michael Jang's RHCSA/RHCE setup guide. I've followed the guide in the book to the dot, though in my opinion a lot of information is missing (step by step ...
1
vote
2answers
2k views

Why are routes set in /etc/network/interfaces not added when the interface comes up?

Here is my interfaces file: auto lo iface lo inet loopback auto eth0 iface eth0 inet dhcp auto eth0:0 iface eth0:0 inet static address 10.20.8.231 netmask 255.255.255.0 ...
2
votes
1answer
40 views

How do you create an network interface without generating an associated route?

I'm having a hard time creating a network interface without a static route being generated to use the default gw. More specifically, I'm trying to create a VLAN interface using the following ifcfg ...
1
vote
0answers
12 views

Point-to-Point VPN: Ping works perfectly, but data transfer works only towards one side randomly

I have two networks connected trough a VPN connection (Wireguard). Let's call them Site A and Site B. The VPN connection is working, routes are set, and all machines from Site A and Site B can ping ...
1
vote
3answers
2k views

How to resolve hostnames with Raspbian 5/5/2015?

I'm trying to share an NTFS drive, or a directory on the drive, via samba, and I have found several tutorials that show it being done in just a few minutes (minus the updates and package installs). I'...