Managing and using network connectivity on a unix system

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9
votes
3answers
35k views

check if interface eth0 is up (configured)

I need to check with a script, whether eth0 is configured. If so, the script will do nothing. Otherwise it will start wlan0. (I don't want both eth0 and wlan0 to be up at the same time). What would ...
0
votes
1answer
26 views

Learn the base of security and defend myself from external attack [closed]

i would like to learn and work on internet security, because thia is a world that is in continuos change and id like to improve myself on it..anyone can help me linking site or PDF where i can study ...
0
votes
0answers
63 views

tcpdump: Couldn't find user 'pcap'

I am using RHEL 5.4, tcpdump is already installed also there is a user pcap but I am getting following message. [root@localhost ~]# tcpdump tcpdump: Couldn't find user 'pcap' [root@localhost ~]# ...
3
votes
3answers
3k views

How do I troubleshoot networking on Debian

Today I restarted my linux box, and following the restart, my linux box has no network connection. Here's what I've tried so far: Use an different ethernet cable that works on my other computer. No ...
35
votes
6answers
70k views

How to limit network bandwidth?

Problem: We are hosting an application on remote server. We need to test it with a limited network bandwidth (for users with bad Internet access). Question: Can I limit my internet bandwidth? For ...
0
votes
0answers
31 views

Set firefox to use non default gateway

I have 2 internet connections. One is set as default, so all traffic goes through it. Other have no default routes added, so no traffic goes through this internet connection by default. boby@hon-...
3
votes
0answers
16 views

Block port on boot2docker vm on virtualmachine

I have Boot2Docker image running in VirtualBox on my mac. I use Kitematic to run docker on my Mac. I have activemq docker running, on port 32769 in boot2docker vm. I have application running which ...
0
votes
1answer
19 views

Debian : Monitoring if server is offline

We have a dedicated Debian X64 server, running projects and we require availability under any situation. Since last 2 days we have noticed that the server went offline for 10-15 minutes, and then it ...
5
votes
1answer
5k views

how to understand the routing table on an OpenVPN client

I just setup the OpenVPN and it is working as expected. However, the routing table of the client is confusing me to no end. Here is the route table: # route -n Kernel IP routing table Destination ...
3
votes
0answers
22 views

how do I make a SIP phone ring with sipsak?

How can I use sipsak to simulate a call so that there's an actual ring, or possibly even a sound is played? thufir@mordor:~$ thufir@mordor:~$ sudo sipsak -v --usrloc-mode --from sip:demo_alice@...
19
votes
7answers
96k views

How can I monitor all outgoing requests/connections from my machine?

My machine is a server so I want to ignore connections being made to my server (e.g. when someone visits my website). I want to see only connections/requests being made by my server to other places. ...
3
votes
1answer
51 views

routing between linux namespaces

I have the following network topology using linux namespaces: .--------.veth0 .--------.veth2 .--------. | ns_snd |------------| ns_mid |------------| ns_rcv | '--------' veth1'-----...
0
votes
1answer
32 views

Routing to the localhost, how does it work?

The output of /sbin/route -n on my Linux box doesn't mention the 127.x.x.x address range, neither it mentions lo interface. Nevertheless ping localhost and ssh localhost are working fine. How the ...
1
vote
2answers
1k views

No Default Gateway route for bond0 / Slave eth* interface gets IP assigned

I have set up a 4-NIC bond on my Debian Wheezy box. After a fresh boot, the system has LAN access, but cannot resolve outside host names or access outside IPs. It seems that this is because the bond0 ...
0
votes
0answers
37 views

USB wireless dongle detected by usb but interface does not come up

I have a wireless dongle based on the RTL8192EU chipset, but there doesn't seem to be any module loaded for it. This is the dmesg output when I plug it in: [ 404.321566] usb 1-1.3: new high-speed ...
2
votes
1answer
38 views

How to set a routing table that prefers wlan dhcp interface as default route

eth0 has a static IP set in /etc/interfaces wlan0 gets it IP dynamically How can I change my routing table and where would I put the command to always make wlan0 the default route so internet access ...
2
votes
2answers
924 views

reset Ethernet bonding without rebooting

I have the following Ethernet bonding configuration: old configuration: bond0 eth0 eth1 bond1 eth2 eth3 new configuration : bond0 eth0 eth2 bond1 eth1 eth3 I have made the ...
0
votes
0answers
13 views

Internet Is Connected But Not Working On Lenovo g580

I installed BackBox 4.6 from https://backbox.org/, but I have no internet access. I am connected via an ethernet cable but I still have no internet. I tried ping but it's not working and no webpages ...
1
vote
1answer
3k views

Trouble switching from DHCP to a static IP on Kali Linux

When I installed Kali Linux 64bit, I forgot to set up a static IP address, and now DHCP determines my address with my router. I have already modified /etc/hosts and /etc/network/interfaces to declare ...
-1
votes
1answer
52 views

Connect Docker container and host to different network

I don't know if this makes any sense, but is it possible to use WiFi in host but only mobile broadband in a docker image?
1
vote
2answers
18k views

How to set up an Internet Connection in Linux Mint?

My machine has wired Internet connection with Windows 7 OS. In connection properties I see service name : ispone obtain IP address automatically obtain DNS server address automatically How do I ...
0
votes
0answers
35 views

How can I use sipsak to send a SIP Invite to lrnlookup.telnyx.com with sipsak?

Here's what I have so far: thufir@mordor:~$ sipsak --from sip:thufir@getonsip.com --password flFl24GB5 --invite-mode lrnlookup.telnyx.com --message-mode error: for the USRLOC mode you have to give a ...
7
votes
1answer
5k views

setup kvm on a wireless interface on a laptop machine

I am trying to setup KVM in ubuntu 14.04 host machine. I use a wireless interface to access the internet in my machine. I have setup the wireless interface in my /etc/networks/interfaces as below. ...
-1
votes
2answers
71 views

Can not set static DNS on debian

I'm using Debian jessie and I don't have network-manager or resolvconf installed and I'm using DHCP. DHCP with static DNS First of all I tried editing: /etc/network/interfaces And adding this: ...
3
votes
0answers
20 views

Bluetooth Tethering, no IPv4 adresse at interface bnep0

I want to tether my mobile internet from my smartphone (OnePlus One, Android) to my Laptop (Debian 8). I want achieve this without using external tools. At the arch wiki page (https://wiki.archlinux....
3
votes
1answer
132 views

Linux router - Throughput speed of clients

I have a computer that is configured as a router with two NIC's, one is connected to Internet, the other is connected to the local network switch. I know that I can get the current throughput of NIC'...
1
vote
3answers
3k views

Split DNS (bind9), match-clients any doesn't work?

I've been fighting with this for the last few days. A few of my entries have external and internal IP's. My internal network is 10.0.0.0/8. When I nslookup pc1.clase.net internally it responds with ...
3
votes
2answers
18k views

why can't this CentOS 7 server see wifi connections?

I recently installed CentOS 7 as the sole OS on an Acer Aspire T. There is no GUI, as it is a server with a terminal-only interface. What do I need to do to get CentOS 7 to be able to see and list ...
1
vote
1answer
31 views

Use same IP for 2 Ethernet Adapters in different Physical networks

We have a Linux Panel with 2 Network Interfaces. On this Panel runs a software wich needs to comunicate to our devices in our network, and needs to be accessible from the customers network. One ...
0
votes
0answers
27 views

ethtool flow control icmp

I'm trying to disable ICMP directly on network cards. I have IXGBE driver 4.4.6 and ethtool 4.5 I've successfully filtered udp4 trafic with : ethtool --config-ntuple eth2 flow-type udp4 action -1 ...
3
votes
2answers
60 views

Assigning static IP address using nmcli

So I'm trying to give a VM a static IP address, this case has been particularly stubborn. The VM is running on a ESXi cluster with its own public IP range. I had it (sorta) working with an IPv4 ...
23
votes
3answers
36k views

what is the meaning of 0.0.0.0 as a gateway?

Can anyone clarify gateway assignment for me? What is the difference between adding gateway as 0.0.0.0 and assigning a specific ip address as a gateway?
3
votes
1answer
277 views

Using iptables to redirect all traffic to local webserver

I'm trying to redirect all traffic on my wifi router to a local webserver using iptables. I'm not sure I have got the command right and also I want to exclude the router IP (172.16.0.1) from the rule ...
-1
votes
0answers
16 views

How to run a function for a specific received packet? [duplicate]

I am doing an experiment for my master thesis. I want to run a function (e.g. multiply two numbers) when a specific packet is received (e.g. a packet with destination TCP port 6666). For example, I ...
0
votes
1answer
32 views

SSH DNS lookup on local IP addresses [duplicate]

As I have come to understand, SSH always goes through the process of reverse DNS lookups whether you are connecting to user@example.com or a local server calleduser@192.168.0.56. I do not know, ...
2
votes
1answer
933 views

redirect web server with no-ip and port forwarding in livebox

I want my Apache web server running on a Livebox (home router appliance running Linux) to be accessible from the Internet (WAN). I installed and configured the application noip2 on my Ubuntu PC. ...
0
votes
1answer
49 views

SSH takes too long to ask for password

I've seen many other questions on this subject but none seem to actually solve my problem. Like any other day, I connect to my LOCAL Raspberry Pi server from my client machine at 192.168.0.5 with ssh ...
0
votes
0answers
44 views

Can detect but not connect to 5ghz?

One night I found out that I could no longer connect to my 5Ghz network. It happened rather suddenly. My fear is that it's a problem with the card, because I also cannot connect on Windows. I can see ...
0
votes
0answers
103 views

cannot ping nodes on same ad-hoc network with certain adapters

I'm setting up an ad-hoc network made mostly of Raspberry Pis and I'm running into a problem where nodes using certain wireless adapter cards cannot interact with other nodes on the network. I know ...
1
vote
1answer
22 views

Add parameters to NFS mount

I try to start Android on device via NFS and TFTP. Everything goes good until Android system starts booting. Something happens with network parameters and connection falls and boot freezes [ 60....
1
vote
0answers
16 views

iptables routing input and forward paths

I would like to know the flow of a packet given the configuration below. Suppose that I setup an adhoc network between my android phone and a NIC on my linux box. I then setup the android phone to ...
4
votes
1answer
44 views

Why does reading /proc/net/tcp take a long time ss is quick to return the same sort of data about the connections table?

On Linux 2.6.32, if you read (for example, cat) /proc/net/tcp, on a very loaded system (for example, a web server), you will find that reading 100K entries takes over 30 seconds. That's a long time. ...
2
votes
0answers
27 views

Multicasting with a Debian Router

I have a local network and I want to use NTP in multicast mode on this LAN. The first step to do this is to get multicast networking to work first. In the network I have 5 Debian machines all ...
0
votes
0answers
52 views

Ubuntu not allowing traffic to ports 1 - 1024

I seem to have encountered a weird issue whereby my ubuntu box is not allowing incoming traffic to the first 1024 ports or so, for both TCP and UDP. My iptables policy is set to ACCEPT for all 3 ...
-1
votes
3answers
25k views

No longer able to reach the Internet on Kali Linux

I'm running Kali Linux on VirtualBox and trying to learn some of its basics. I know it's based on Debian but I come from Windows so I'm new to Linux and networking in general. My problem is that ...
3
votes
0answers
41 views

SoftIRQs and Fast Packet Processing on Linux network

I have been reading about performance tuning of Linux to get the fastest packet processing times when receiving financial market data. I see that when the NIC receives a packet, it puts it in memory ...
4
votes
1answer
3k views

Accounting for /proc/net/dev reported traffic

I noticed that according to /proc/net/dev I am constantly receiving around 6Kb/s on my wireless usb interface. But I can't account for anything even close to that with the individual connections that ...
1
vote
0answers
31 views

Shutdown problem on Lenovo G50 after installing Linux Mint 17.3

After installing successfully Linux Mint 17.3 on Lenovo G50, its not rebooted. The error is : [397.188708] Fixing recursive fault but reboot is needed! [400.538090] init: mdm main process (2363) ...
1
vote
1answer
46 views

Debian - No wired connection after restart

Last night I was working on my computer, for reference I'm using i3, and decided to uninstall XFCE4, as I felt I didn't need it. The next morning I turned on my computer and have no wired connection. ...
1
vote
0answers
27 views

Bash check if firefox use internet

I want to check how much internet use Firefox with a shell script. Here I found good examples to see performances. #!/bin/sh free -m | awk 'NR==2{printf "Memory Usage: %s/%sMB (%.2f%%)\n", $3,$2,$3*...