Managing and using network connectivity on a unix system

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3
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2answers
1k views

Open and redirect port

I'm trying to set up SNMP for a router so I can monitor it from an existing Nagios installation on an off-site server. I'm having trouble getting the router to respond to SNMP requests from the WAN, ...
23
votes
5answers
18k views

On-the-fly monitoring HTTP requests on a network interface?

For debugging purposes I want to monitor the http requests on a network interface. Using a naive tcpdump command line I get too much low-level information and the information I need is not very ...
4
votes
2answers
42k views

Host unreachable and I do not get why

I can not open a specific website. This is a website hosted by our company, and I know it is up. However, these are my symptoms: VARIABLES: host.com - the website I can not open x.x.x.x - the IP of ...
5
votes
2answers
4k views

Connection ec2 instance operation timeout error using ssh

After creating a new instance, I am trying to access my instance like below: ssh -i private_key.pem root@my_instance_public_domain but the operation is timing out. I have updated the private key ...
2
votes
3answers
5k views

Auto connect to a wireless network (Ångström Linux)

I am using Ångström Linux on BeagleBoard-xM. I have installed a RTL8188SU USB Wi-Fi adapter and configured it properly. But it doesn't connect automatically even though I have marked the interface as ...
1
vote
1answer
511 views

How to tell what wireless protocols my network card is using?

I want to know which wireless protocol my card is currently using. I found a similar question that tells you what network protocol your card supports, but I want to confirm that my card is actually ...
11
votes
2answers
2k views

How can I create a virtual ethernet interface on a machine without a physical adapter?

I have a Dell XPS 13 ultrabook which has a wifi nic, but no physical ethernet nic (wlan0, but no eth0). I need to create a virtual adapter for using Vagrant with NFS, but am finding that the typical ...
0
votes
3answers
4k views

How can I reinstall Network Manager after uninstalling it?

I am running a version of RHCE6 on my laptop, and lately I've been trying various stuff about network configuration through command line. Last night, I tried removing the NetworkManager using yum ...
6
votes
1answer
852 views

AP randomly gets unreachable for the clients while hostapd is running

I got an old PC running as router which has 3 NIC and 1 wifi PCI card TP-Link L-WN751ND. This box runs Debian Wheezy, hostapd, dhcpd etc. The problem is that AP randomly gets unreachable for the ...
3
votes
1answer
3k views

problem with server bonding interface configuration

We are facing some problem with configuration of servers: There are 2 servers, each one contain 2 NICs which are in bond. Each server is connected to 2 Cisco switches (one connection from each NIC to ...
0
votes
0answers
18 views

How to tune dhcp networks configuration?

I'm not sure how should I configure my guest VirtualBox networks. So far, I figured out how to override this configuration so that I can connect to machines on both networks. But I'm manually ...
2
votes
1answer
24 views

How do I detect which device was recently created by pppd?

I'm trying to setup a VPN over SSH using PPPD (following the Arch Wiki). The command given is: /usr/sbin/pppd updetach noauth silent nodeflate pty \ "/usr/bin/ssh root@remote-gw /usr/sbin/pppd ...
3
votes
4answers
21k views

Yum update problems on CentOS 6.5 minimal as VMware guest

INFO: I am using Windows 7 Pro (64bit) with VMware Workstation version 10.0.1 . I am using CentOS(64bit) 6.5 minimal, for the first time. I am running this from my workplace network, which may use a ...
1
vote
2answers
666 views

Command/scripts to check the Reverse DNS Lookup time

I am working on a project in which one master communicates with numbers of slaves. For that it has to make connection with hosts in network. But sometimes it hangs. I think that the reason behind is ...
1
vote
1answer
642 views

How to set up a “child” proxy that doesn't need a “parent” proxy

I run Linux on a laptop that is sometimes on a corporate network which uses an NTLM proxy server, and thus I have cntlmd running on the laptop as a child proxy to connect to the parent (corporate) ...
2
votes
2answers
45 views

Add virtual bridge without the loss of networking?

There is a dedicated server without KVM-over-IP support. The server 'owns' two IP addresses, and one of those is used for eth0 at the moment. The user needs to add a virtual bridge, in order to ...
0
votes
1answer
14 views

How to capture traffic from a website using tcpdump

I need to capture traffic to https://gmail.com using tcpdump. I solved this by using tcpdump -n dst host <ipaddress of gmail> But is there any way I can directly specify gmail.com instead of the ...
0
votes
1answer
32 views

Connecting to a WPA2 network

For connecting to networks use WPA/WPA2 with PSK, from here wpa_passphrase your_network_name your_password > wpa.conf ifconfig wlan0 down ifconfig wlan0 up iwconfig wlan0 essid ...
1
vote
2answers
59 views

What exactly happens in Linux internally when an ethernet cable is connected?

I would like to understand what exactly happens when a cable is being connected to the Ethernet port (assuming dynamic IP addressing): What services are being run and how are they triggered? What ...
8
votes
2answers
13k views

Fast way to copy a large file on a LAN

I am having some trouble with NFS, and I'd like to try using just plain old TCP. I have no idea where to begin, though. Hardware-wise, I am using an ethernet crossover cable to network two netbooks. ...
4
votes
0answers
60 views

Disable networking only inside of a single terminal

I want to run a command in the terminal to disable networking, just in that terminal. How can that be accomplished? I'm running OSX. Note: I only want to disable the networking in that terminal. ...
3
votes
2answers
2k views

Ping IP works, nslookup fails. New Kernel

I am compiling my own 3.14 kernel. I fear I may have left out some important networking feature to get DNS working. I can't resolve domain names. I can ping my DNS server. I can resolve using that ...
2
votes
1answer
30 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
1answer
26 views

dd wrt firmwire file prompt password while extracting

I am a newbie in using dd wrt firmware development. Last day i download a dd wrt firmware dd-wrt.v24-21676_NEWD-2_K2.6_mini-e900.bin for Linksys E 900 router. I need to extract this image for ...
0
votes
1answer
102 views

Compile network card driver on debian

I buy a new network card , D-Link DGE-528T. My OS is Debian(Jessie) kernel : 3.16.0-4-amd64 but it can't detect the new network card, so I must to compile driver by myself. follow README file. ...
1
vote
1answer
76 views

Enable Promiscous mode in CentOS 7

How to enable promiscuous mode on network adapter. I have tried by adding PROMISC=yes in /etc/sysconfig/network-scripts/ifcfg-ensxxx but no effect even after network restart or rebooting the system.
1
vote
1answer
38 views

How can I monitor network connections for an app

I'm running a chat application on my machine called foo - how do I view all connection attempts (failed or successful) for foo? I have attempted this with netstat, but I am unsure how to associate ...
1
vote
1answer
610 views

Randomize external port when doing NAT with iptables

I want to configure a NAT behavior different from the default one implemented by iptables. In this example: iptables -t nat -A POSTROUTING -o eth1 -j SNAT --to-source 193.49.142.107:2000-400 The ...
2
votes
3answers
3k views

How to change user agent on all http requests made from my machine with Squid intercepting proxy?

I'd like to change the user agent on all HTTP requests made from this machine. It's easy enough to change the user agent in each browser, but other apps also make http requests. It's vital I catch ...
1
vote
0answers
15 views

interface associates with access point, but dhclient hangs

I'm having an issue connecting to my access point from the terminal. I'm using iw to connect: iw wlan0 connect MY_AP Running iwconfig wlan0 shows that it's associated with the access point. But ...
0
votes
1answer
40 views

How to make virtual interface ping to a host in the network

I crated a virtual interface as indicated in this link. sudo modprobe dummy sudo ip link set name eth10 dev dummy0 sudo ifconfig eth10 up sudo ifconfig eth10 192.168.1.150 now if I want to make a ...
0
votes
2answers
97 views

Provide security settings before connecting over WiFi in Mint 17

A little while ago I upgraded my laptop from Linux Mint 16 to 17. Everything went fine, but now I can no longer connect to a specific wireless network that I have at work. When I try to connect, it ...
0
votes
1answer
2k views

Set up network with static IP and wpa_supplicant on Debian

On Debian, I am trying to set up my network to use ad-hoc mode with a static IP address. I also want wpa_supplicant to be running so that I can scan use it to scan for WiFi networks in range. To get ...
1
vote
1answer
37 views

USB Wi-Fi correctly installed but it can't access the Internet, Debian Wheezy

I have a USB Wi-Fi stick correctly installed on my Debian Wheezy system. from dmesg: ADDRCONF (NETDEV_CHANGE): wlan0: link becomes ready from ip a: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> ...
3
votes
3answers
645 views

Averaging output of dstat

I need to average upload and download speed using dstat -n. How can I add all the received and sent data sizes that appear after dstat -n, so that I can add them and find average upload and download ...
2
votes
1answer
55 views

How do I disable network interfaces from loading at boot without Network Manager?

The machine I'm using has 4 network interfaces, only one of which is currently being used (the other 3 are not plugged in at all). Currently when the machine is restarted it is delayed by a few ...
12
votes
3answers
26k views

VirtualBox: two network interfaces (NAT and host-only ones) in a Debian guest on Ubuntu

I created a Debian VM on VirtualBox with two interfaces: a NAT one (for accessing internet) and a host-only one. However, I do not know how to make both interfaces work at the same time. If I the ...
0
votes
1answer
47 views

Samba and usbmount: can't write on automounted device

This is my problem: I configured my RPi with Debian: Samba shares /media/, that is readable-writeable-executable from my home network usbmount automount USB devices when inserted in my RPi, in ...
2
votes
1answer
100 views

Connect OpenWrt router to home wifi AND open wifi

I've noticed I'm within comfortable wifi range of a nearby coffee shop's open connection. I have an OpenWRT router that I'm not using, and thought it might be handy to have this connected to my home ...
4
votes
0answers
42 views

Is it possible to set interface name permanently in Raspbian?

I'm using 2 wifi dongles. First one is used to monitor and second one is used to access internet. Even if I changed /etc/udev/rules.d/70-persistent-net.rules as below, at startup sometimes wlan0 ...
1
vote
0answers
22 views

Need help with a network manager command line script

I am looking for some help in creating a script. As RHEL boots up and I login, I'd want to manually run a script which would: Identify the active ethernet interface (the eth ID being used). Ask ...
7
votes
4answers
1k views

Simplest way to send files over network

What is the simplest and most versatile way to send files over the network to other computers? By that I mean computers that other people are using at the moment. I don't think SSH works if the ...
1
vote
0answers
24 views

Linux Container LXC Intra Host Networking Issues

I have a problem that I cannot seem to resolve. I have two hosts M and N. A container in host M can ping the gateway, its host and all containers in Host N but cannot ping any co-hosted container in ...
0
votes
0answers
36 views

Bridge interface - add default route

I used to connect my ubuntu 14.04 laptop on office network via eth0 and the route table gets updated with the office network gateway ip in auto mode. Now, i changed my /etc/network/interfaces ...
1
vote
1answer
44 views

What is blocking: Firewall and tcpwrapper?

Is it possible to find whether firewall(Iptable) or tcpwrapper is blocking a connection without accessing the remote server? (tcpdump?) Thank you,
1
vote
3answers
47 views

is there a system-wide “extension” to /etc/services that does not get replaced on package updates?

I know how to use /etc/services but if I change it and the inetd package is later updated via apt-get to a new default one, my changes are gone (happened to me on a apt-get dist-upgrade from Debian ...
0
votes
0answers
20 views

How to add routes multiple times in routing table?

Need to add same route multiple times in the routing table, or is there a way to maintain references in the routing table entries ? (may be with different priorities etc.) Am working on a switch ...
2
votes
1answer
2k views

Can I change uuid for network interface in ifcfg-eth* using uuidgen?

I'm creating a script which configuration the network interfaces. The script which generates /etc/udev/rules.d/70-persistent-net.rules and names interfaces to my preference. In CentOS 6.5, my ...
4
votes
2answers
109 views

Did this tutorial block pings to my server?

I am a programmer teaching myself linux admin stuff. I followed this tutorial to setup a firewall on a VPS. As a part of that tutorial, I block all traffic except for web traffic and SSH traffic. I ...
16
votes
1answer
31k 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 ...