Questions tagged [networking]

Managing and using network connectivity on a unix system

2
votes
1answer
930 views

iperf connect failed: Operation now in progress

I have installed iperf on two computers using yum install iperf. On server A, i ran iperf -s, on server B I ran iperf -c ipv4here I got this error: connect failed: Operation now in progress I ...
1
vote
1answer
930 views

Hostapd SSID disappears after some seconds

I'm using hostapd to share another wifi connection through my raspberry pi zero w bult in wifi card. After the raspberry pi boot I can see my SSID in my phone and even connect to it and use it for ...
52
votes
2answers
127k views

Using ip addr instead of ifconfig reports “RTNETLINK answers: File exists” on Debian

I have a Debian system working as a wireless router with eth0 and wlan0. Now I added an additional network manually on eth1 with ifconfig: alix:~# ifconfig eth1 192.168.0.2 netmask 255.255.255.0 alix:...
6
votes
1answer
571 views

iptables and cgroups v2 (netfilter's xt_cgroup)

I can't seem to match processes running in cgroup v2 hierarchies with the cgroup module of iptables. I am running Linux 4.13.0 with all required modules: $ grep CGROUP <kernel_config> ...
0
votes
0answers
9 views

CUPS and a DeskJet on the parallel port - How to fix my printer setup?

I installed KDE KaOS onto a Dell XPS630i. I have an HP DeskJet 500C printer connected to the machine through the LPT on a PCI-e expansion card with a com port and an LPT. The card and printer DO ...
21
votes
11answers
4k views

How can I ping multiple IP addresses at the same time?

I'm aware of the methods where you can run a Bash for loop and ping multiple servers, is there a Linux CLI tool that I can use which will allow for me to do this without having to resort to writing a ...
0
votes
1answer
33 views

Switch between DHCP server and client on eth0

I am working with a arm micro-controller. Currently the controller is configured as a dhcp client on eth0 (ethernet jack) and as a dhcp server on eth1. I want to configure it to also serve dhcp on ...
0
votes
0answers
8 views

OVS Bridge & Layer 2 Port Isolation

I'm curious if it's possible to, using ofctl, essentially drop all traffic between ports on a bridge, except destined to the bridge's internal interface. EG: The bridge has an internal port, and two ...
1
vote
0answers
356 views

Why linux drop packets in netif_receive_skb?

I have a linux box where we see a lot of (30%) TCP retransmission in tcpdump when receiving (downloading) files from outside. Using the dropwatch utility we see many packet drops in kernel function ...
1
vote
0answers
57 views

How to diagnose slow upload speeds on Ubuntu Server 18.04

I'm currently running Ubuntu Server 18.04 on a home server build to act as a Plex server, among other things. I have it connected via ethernet (with a 5-port switch between it and the router), and get ...
2
votes
0answers
297 views

How to avoid dhcpcd sabotaging docker0 network?

How to reproduce: Start dhcpcd unless it's already running Restart the docker daemon Run docker run -it busybox ping -c 1 1.1.1.1 Expected behaviour: The command should succeed. Actual behaviour: ...
0
votes
0answers
19 views

Is it possible to configure eth0 to be server and client [closed]

Can I configure eth0 (ethernet jack) to be a dhcp server or client whenever I want? If so how do I go about doing that? Any ideas are appreciated. Thanks
1
vote
0answers
21 views

What is the difference between mode0 and mode2 in network bonding ? Why can mode0 not be added to a bridge?

I am very confused about the difference between mode0 and mode2 in network bonding. Why does mode0 conflict with bridge?
2
votes
1answer
1k views

How do you route to secondary interface on the same physical port?

INTERNET<->(wan)BRIDGED_DEVICE(lan)<->ETH_ROUTER<->LAN Problem: Need to access web server on BRIDGED_DEVICE's LAN from INTERNET via ROUTER (BRIDGED_DEVICE web server cannot be accessed form ...
2
votes
1answer
79 views

Why linux allows connection on a different interface ip even if forwarding is disabled?

The system has two interfaces 1.1.1.1 and 1.1.2.1. The sysctl net.ipv4.ip_forward is either disabled or enabled but iptables -P FORWARD DROP is set. Now setting 1.1.1.1 as default route on another 1....
1
vote
0answers
22 views

Ubuntu not accepting some TCP/IP connections

So I am absolutely losing my marbles here. Ubuntu 18.04.2 I have Docker + Portainer installed via a local container. I can access the portainer UI via https://ip-address:9000 However, I also ...
0
votes
2answers
2k views

Unable to delete “Wired connection 1” using ncmli

Log: NAME UUID TYPE DEVICE Wired connection 1 d1b2ff35-4d72-3bd5-a8e2-d3d9fefce205 802-3-ethernet eth2 admin 6186afb2-7253-...
0
votes
0answers
33 views

Slow download speed with rtl8821ce on Pop!_OS 18.04

I recently bought a HP 15-da0206ng laptop and since my goal was to finally switch from Windows to Linux I installed the Linux distribution Pop!_OS 18.04 LTS which is built on Ubuntu 18.04 LTS. After ...
0
votes
1answer
23 views

Encrypting Wifi Password When Using Wicd

Inspired by this answer, I'm wondering if there is a (relatively) painless way to "hide" the wifi password(s) that is/are present in the /etc/wicd/wireless-settings.conf file. I travel a lot and ...
-2
votes
1answer
25 views

Linux tool to monitor network performance

I need some suggestions about monitoring various network statistics (like RTT, Packet loss, Jitter, packet retransmission) using linux command line. I have tried "SS" command but SS command gives ...
0
votes
0answers
15 views

Issues with NFS/CIFS shares and martian packets when using two interfaces

Background: I have an isolated LAN. The switch is configured with 3 VLANs Here is how my network is setup VLAN Subnet Mask CIDR Range Gateway 10 192.168....
0
votes
1answer
44 views

Policy routing with 2 NICs on the same network seems to not do anything

As noted by dirkt, I'm missing information: This is the continuation of this question, but to summarize, I'm trying to receive a lot of multicast traffic, more than one interface can handle, so in ...
0
votes
1answer
894 views

Understanding network problem (syslog)

I am running a lubuntu 14.04 server and its always worked well, except for the last couple of days it keeps dropping off the LAN. I am using a couple of powerlink adapters to connect it up as WiFi was ...
60
votes
6answers
106k views

Allowing a user to let listen to a port below 1024

I need to allow a user (different from root) to run a server listening on port 80. Is there any way to do this?
1
vote
1answer
51 views

Setting 'DF'-bit in ip-header inside pcap file

There is some .pcap-file with fragmented ip traffic. I replay this file with tcpreplay, but also I need to replay it with DF (don't fragment) bit set in some packets. I supposed that tcprewrite will ...
0
votes
0answers
20 views

Manjaro not connecting to some websites

I have an issue where some network requests return ERR_ADDRESS_UNREACHABLE and others resolve successfully. Success and failure depends on the domain, for example requests to amazon.com resolve while ...
1
vote
1answer
18 views

how to get packets log which are dropped by rp_filter=1

I do need a log of packets which are dropped by rp_filter ... how to do this logging ? which logs how to enable.
0
votes
1answer
1k views

How to set proxy with a config file provided in freebsd

I'm currently trying to update and install packages and other things on a FreeBSD server, but I’m blocked by my proxy. I'm in an university, and there are a few proxies before to go on the internet. ...
0
votes
2answers
57 views

Other machines here in our office can't access my local website within the same network

I'm developing a portal and the main aim for this portal is for all my colleagues (whose machines are connected to the same network) to access the portal. I have tried to reinstall my apache server ...
0
votes
1answer
31 views

How to bind a network namespace to a interface device through a macvlan

I am trying to connect a new network namespace to a netwrok device with the following commands: # create macvlan and associate it to network device in bride mode ip link add macvlan1 link dev1 type ...
1
vote
1answer
45 views

Debian 'mount': same command different errors

I am trying to mount one of network share to my laptop. I am using following command sudo mount -t cifs //server.name/shared /mnt/myfolder -o user="username" However, I am getting very different ...
3
votes
2answers
1k views

How do I route a spare network interface through an SSH tunnel?

I just bought a Raspberry Pi and I am wanting to route an ad hoc wireless network interface fully through an SSH tunnel that was created using another wireless interface. I want to do this so that I ...
1
vote
0answers
24 views

Understanding Networking Issue Ubuntu 18.04

I have a server setup where I've bonded 4 interfaces (bond1) and connected this to a physical switch. I have added this bond1 to an OVS switch ovsbr1 with VM's attached to ovsbr. It seems there was a ...
1
vote
1answer
1k views

FreeBSD: adding ip alias to interface breaks network on primary ip

I am trying to add an alias to my network card (I would like to use jails) on my FreeBSD box. It is running version 10.2-RELEASE-p7 (generic amd64 kernel). The machine is running in a Hyper-V virtual ...
0
votes
1answer
21 views

Limit a VPN server's services to VPN connections only

I have a jump server and I want to put it behind a VPN, I do not want to deploy a separate VPN server and put my jump server behind it. I thought of installing OpenVPN directly onto my jump server and ...
0
votes
1answer
49 views

How can I upgrade a primitive Netcat shell to a fully-featured login shell with tab-completion and line editing?

How can I upgrade a primitive Netcat shell to a fully-featured login shell with tab-completion and line editing? Suppose I start a remote (reverse) shell using Netcat as follows: nc -lvp $port nc $...
0
votes
1answer
22 views

Dig: connection timed out; no servers could be reached. But ping works?

When I try to run the dig command against either my servers IP or nameserver I get an error: root@kali2:/etc# dig q-type=soa @192.168.100.10 ; <<>> DiG 9.11.4-P2-3-Debian <<>&...
22
votes
3answers
65k views

How to permanently disable a network interface?

I've brought down a network interface with ifconfig wlan0 down, but every few hours or so, the wlan0 interface comes back up and I can't figure out why. I don't restart the machine, never changed /...
0
votes
0answers
43 views

How to access data written in a socket without reading it [migrated]

I'm working on an embedded system having Linux. A client thread is writing some data in the socket but what server thread is reading on the other side isn't the same as it was written. Which is ...
3
votes
1answer
25 views

Execute a command when upon receipt of a TCP connection

I would like to run a bash command when a remote connection is successfully established to a specified local open port. I have looked into netcat and socat, but I'm not sure if either have the ...
1
vote
1answer
2k views

CUPS: How to troubleshoot “No printers found” condition?

If I point my browser to http://localhost:631/admin and click on the Find New Printers button, the page that comes up reports No printers found. My (wired, wide-area) internet connection works fine (...
1
vote
0answers
26 views

PXE Boot: “Failed to load ldlinux.c32”

I'm trying to create a PXE server on my raspberry pi, but if I try to boot, the client shows the Error "Failed to load ldlinux.c32". This is my folder structure of the tftp folder: Here is my ...
8
votes
2answers
1k views

Trying to understand Auto reconnect WIFI method

I found this method of reconnecting the WIFI dongle from this post. But, I want to be clear on how it works, before I try and implement it. Go to /etc/ifplugd/action.d/ and rename the ifupdown ...
1
vote
1answer
204 views

Timeout when mounting EFS on EC2

Let us say I have an EC2 VM which we will call V in security group S1. I have an EFS mount point which we will call M in security group S2. Everything is in the same VPC, on the same subnet, in the ...
1
vote
1answer
35 views

NTP - localhost timeout - source network uses eth0 instead of lo

ntpq -p commands are timing out for me in a centos 6 server. # ntpq -pn 127.0.0.1: timed out, nothing received ***Request timed out tcpdump result shows me that it is using eth0 instead of loopback ...
1
vote
1answer
36 views

How to connect a namespace to a physical interface through a bridge and veth pair

My attempt is modeled on the this tutorial. I am able to ping from the namespace to the network if the physical interface is not assigned to the bridge. # Create namespace ip netns add namespace1 #...
0
votes
1answer
18 views

How do I check if my VM is using vhost-net driver for networking

In KVM, NIC model can be set to virtio (latest) or the older e1000 (not recommended, emulated). In virtio, one has the option of using vhost-net driver or qemu. vhost-net and qemu differs in how ...
0
votes
0answers
28 views

Ethernet interface not working on embedded QNX device

I have A device running QNX which I can connect to over WiFi through a netgear router but which doesn't connect over ethernet. I'm pretty sure it has to do with the netmask which is in a format I ...
0
votes
1answer
56 views

What order is “/proc/net/tcp” being displayed

When you view the /proc/net/tcp or the /proc/net/tcp6 files you are able to see the open ports on the machine itself. But just wondering in what order are these entries being listed in?
10
votes
7answers
22k views

rsync keeps disconnecting: broken pipe

I'm using rsync to backup my home directory. This has been working fine for a long time now. Here's the command I'm using: rsync \ -pavz \ --delete \ --exclude 'mnt/' \ --exclude '....