Managing and using network connectivity on a unix system

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2
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3answers
75 views

One-liner for getting an IP address of an internal DNS name?

I have an internal DNS name for which I'd like to get the IP address. Is there a nice Bash one-liner I can issue to convert internalip1.mydomain.com into 10.10.10.10?
0
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0answers
63 views

How can I configure multiple tap interfaces for a single KVM virtual machine

I am trying to setup a VM using Linux KVM for a F5 BIG-IP VE deployment (used in a lab) ...
1
vote
0answers
20 views

Transport keyboard/mouse events to a keyboard/mouse-less remote host

I want to send keyboard and mouse events from a small ARMv7 computer board to a remote one, which has no keyboard nor mouse. I'm planning to send these events on a locally implemented CAN bus. The ...
1
vote
1answer
29 views

I need dhclient to flush IP address/routes when link goes down

I am running one Ubuntu Server 14.04 with network configuration using /etc/network/interfaces and so ifup/ifdown scripts. I realised that if I configure one interface in DHCP mode, then I unplug the ...
1
vote
1answer
46 views

How do I run a program without network access? [duplicate]

I am making a program that scrapes information from some web services. I want to test how my program reacts when it can't reach the web service, like if the web service is down or if the local ...
0
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0answers
27 views

how do I disable the firewall through YaST?

The fine manual states: The Start-Up section defines how your firewall will start. You can either have the firewall start automatically when booting (recommended), or you can set the firewall ...
4
votes
1answer
140 views

what is “rfc3442-classless-static-routes” in /etc/dhcp/dhclient.conf

I am trying to debug DHCP on my laptop (I am using dhcping and dhcdump to see what the DHCP server sends back). Following is my /etc/dhcp/dhclient.conf. option rfc3442-classless-static-routes code ...
2
votes
2answers
101 views

How to print from a given range of ip addresses every class-c with the last octect replaced by an asterisk

example: I have a range from 10.0.100.0 to 10.0.224.0 and I want the output like this: 10.0.100.* 10.0.101.* 10.0.102.* and so on
0
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0answers
89 views

can't connect to remote host with MySQL…firewall problem?

I've granted privileges to thufir for remote access through the shell (correct?), but cannot seem to actually connect. The router firewall has SPI to off. I've disable the IPv6 firewall on the ...
0
votes
1answer
50 views

WiFi only connects to my router, not to any other access point

I have a Raspberry Pi 2 with a WiFi USB dongle. I don't know the brand or model, I got it for free with my Xtreamer Mk1 in 2009. My Windows 7 PC installs some generic Realtek RTL8191SU WLAN adapter ...
0
votes
0answers
43 views

eth0/usb0 bridge breaks after removal and replacing android phone

I'd like some help with a networking bridge issue I've run into. I'm trying to make a bridge with eth0 and usb0 (my android phone). After running the brctl commands the bridge works wonderfully. But ...
1
vote
0answers
15 views

shared filesystem with offline access

I would like a shared filesystem with offline access. I have two machines. One is a light laptop with a small amount of SSD storage that I carry with me. The other is a stay-at-home computer with much ...
1
vote
1answer
66 views

Test for open TCP port in bash script

I want to delay the script execution until a certain server process is ready, which it is once it accepts incoming TCP connections. How do I test if a local TCP port is open (I get a SYN/ACK answer)? ...
4
votes
2answers
445 views

Using bash's `/dev/udp`, how would I know if the port was open?

I do not have access to netcat or nmap so I'm trying to use bash and the /dev/udp/ special files to test ports. I could do something like: echo "" > /dev/udp/example.com/8000 But $? is always 0 ...
0
votes
0answers
51 views

Dropped connections with b43 driver using Broadcom BCM43228 wireless chip on Arch Linux

I managed to get my wireless working with the b43-firmware package in the AUR and for at least a month it worked perfectly. However, recently the internet connection has been dropping out. I'm ...
1
vote
0answers
15 views

Fair traffic classification using TC

I want to apply a qdisc I developed on myself (quite similar to netem. Think netem.) to several IP-addresses using the filter classifier. No problem this far, I could do so using the prio qdisc or HTB ...
1
vote
0answers
150 views

Make docker containers accessible via vpn

I have three physical machine A, B, C, each of them has docker installed. I want to install openvpn server on machine A, and install openvpn client on B and C. B and C will connect to A. I want to ...
0
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0answers
40 views

how to set a route and firewall for a static ip

These directions on setting the static ip address for vicidial seem at once very specific and overly broad: Type 'yast lan' and press ENTER Optionally, you can type 'yast' and navigate to the ...
0
votes
1answer
75 views

why can't I ping Google with a static IP address?

I'm trying to install vicibox, an OpenSUSE distro which includes Asterisk. The fine manual says to set a static ip address with yast lan. What's the difference between: ││[ ] Change Hostname via ...
0
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0answers
26 views

static ip address in yast

I think that I set the FQDN for the server in yast. How do I set the static IP address with yast? I go to network devices => network settings, see my NIC: YaST2 - lan @ arrakis Network Settings ...
0
votes
1answer
18 views

How does tcp communicate back to the application? [closed]

Are there standard sytem calls to send data to TCP? And back? How does TCP tell the application to send more or less?
0
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0answers
33 views

how do I set a hostname in yast?

how do I set the hostname, FQDN, in yast? I ran yast => network devices => network services => hostname/DNS: YaST2 - lan @ arrakis Network Settings ...
0
votes
1answer
41 views

How do I limit inbound and outbound bandwidth to and from a specific host on CentOS

As the title says, I am trying to limit inbound and outbound bandwidth to and from a specific host on CentOS. The reason is that this host consistently uses a large amount of bandwidth and this needs ...
2
votes
2answers
40 views

mknfsmnt fails with “System call error number -1”

This system is part of a cluster and the other node mounts the nfs share successfully. This is currently the active node which means it has a secondary service ip address. I think this is related to ...
2
votes
1answer
212 views

Understanding why such a discrepancy in network transfer?

Summary: I can't understand a peculiar discrepancy in network transfer. Why is there such a discrepancy in syncing from one machine to the other and vice versa? Also: Given the maximum network ...
0
votes
1answer
37 views

Why can `lsof -i` not show an open connection which `netstat -n` lists?

A strange situation. I started telnet 0 8081 and lsof -i (run under root) doesn't list this connection, but netstat -n does. Why can this be?
3
votes
0answers
46 views

Trickle not behaving as expected

I'm using Ubuntu Trusty 14.04 64 bits. I've installed trickle network shaper from repositories and I performed some tests: No limits I executed this command to test somehow my network download ...
1
vote
1answer
42 views

Sending messages to another user over network

This one is similar to Sending messages to another user except that I want to accept messages over network. If there is a way to just unblock the port to receive messages, that would be fine. If ...
0
votes
1answer
55 views

Local system doesn't forward to intended port defined in OpenShift proxy app

I've set up a proxy server via OpenShift based on this tutorial and used a few days by forwarding my local system's ports to remote app's ports: $ rhc port-forward AppName The result in the proper ...
0
votes
2answers
56 views

How to setup routing tables to connect two subnets

How do I setup my routing tables to allow traffic between two subnets I have a gateway box with two NIC's 1st NIC [eth0] is connected to my outgoing network side and DSL modem and has subnet ...
2
votes
1answer
62 views

Is it possible to add some 'PXE Network Boot' option to GRUB?

This is an example of my available GRUB menu boot options: 1 menu label ^ 1) Xubuntu 14.04.02 LTS 2 menu label ^ 2) Windows 7, x86 & AMD64 3 menu label ^ 3) Windows 8, ...
0
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0answers
51 views

Ip route: Routing with two interfaces (only one connected to Internet)

I have this problem: I have a laptop with WiFi and eth. The WiFi is connected to the internet and has the following config: 192.168.1.100 and 192.168.1.1 as gateway The eth is connected in this way ...
0
votes
0answers
28 views

All packets after the first one on tun0 are dropped

I'm trying to run the Aventail VPN 10.7.1.449, and it doesn't work since every packet after the first one is getting dropped: tun0 Link encap:UNSPEC HWaddr ...
3
votes
4answers
182 views

Shell Scripting: Proper way to check for internet connectivity?

I found scripts that say they check for internet connectivity. Some check the ip address if the interface is connected BUT it does not check for internet connectivity. I found some that uses ping like ...
1
vote
1answer
93 views

Missing network list in menubar after using airmon-ng

After using airmon-ng in kali linux the list of available networks is missing in the menu bar at the top. Can anyone please tell me how to "reactivate" it? When i use iwconfig it shows up an entry ...
1
vote
0answers
66 views

Problems forcing Debian to obtain IP from predetermined server address using DHCP from nameserver on network

I am having trouble getting my Debian server to change the address where it requests its IP address. I currently have two routers. My primary distributes IP addresses to various machines on the ...
3
votes
1answer
97 views

NIC statistics explanation (ethtool -S eth1)

What is the meaning of each of the results from ethtool -S eth1 command? For example, when I used ethtool -S eth1, I got something like this: >root@localhost ~]# ethtool –S eth1 >NIC ...
0
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0answers
29 views

why do I have so many open socket handlers and netstat DGRAM entries?

I run on a RPi (Raspbian 3.12.35+ #730 PREEMPT Fri Dec 19 18:31:24 GMT 2014 armv6l GNU/Linux) a daemon in Python 2.7.8 which queries various APIs via requests and provides itself an API for another ...
0
votes
2answers
109 views

Cannot access internet through OpenVPN

I have set up an openvpn server, generated a certificate and downloaded it to my client machine. After importing the client.ovpn file in the network manager, I can still ssh into the server itself, ...
4
votes
1answer
110 views

SSH server listening on multiple ports with passwordless access not allowing connections to second port

I have my Synology NAS running an SSH server listening on the default port 22 and I set up passwordless authentication with a public/private key and a passphrase: From sshd_config: ...
0
votes
0answers
24 views

Connected to wifi but no internet access

Unable to be pinged from other machines (other machine returns 'Request timed out') Unable to ping the router or any other device (returns 'destination Host unreachable) Unable to use the internet ...
2
votes
1answer
45 views

make my Debian laptop switch autoamtically to a backup connection

I have a laptop with Debian OS installed under it. It is initially connected to the internet using an Ethernet cable (via a modem) and I want to automatically switch to a backup wifi connection (which ...
0
votes
0answers
15 views

How to restrict access of a process to specific ports?

How can I restrict access of a process to use only specific ports, or block it if it uses non-allowed ports?
2
votes
1answer
51 views

Secure way to allow any user to run programs in specific network namespace

I have a cell modem connected to my server that I want to use as a means to get notification emails out when the landline dies. To nicely separate normal network access and this exceptional cell ...
1
vote
0answers
79 views

links are always NO-CARRIER, but expected to work

At some point I start receiving "NO-CARRIER" error message. What does it mean and how can I fix it? My links are "physically up" - green lights are blinking. On the opposite side link is up, but no ...
2
votes
0answers
51 views

Why is dhclient making DHCP requests on a static interface?

I'm setting up a new Debian system. I have a static IP configured on an interface in /etc/networks/interfaces like so: # The loopback network interface auto lo iface lo inet loopback # The primary ...
1
vote
1answer
113 views

Loading kernel modules that were compiled for another kernel failed

I want to load kernel modules, ip_gre.ko and gre.ko, on a embedded-device running embedded-linux to make that device to support GRE protocol. Since I do not want to change Embedded-linux device's ...
0
votes
0answers
87 views

Best way to transparently redirect traffic to proxy

I've implemented a wireless router using hostapd on Debian Wheezy running on a Banana-PI. To access the internet, this router is attached to another network that I haven't any control of via ethernet. ...
0
votes
0answers
23 views

Send raw IP packets to a server, forward them to their destination addresses, and give responses back to clients

A similar question was asked here. But I'm not sure I need OpenVPN for what I'm going to do. I have an Android device with a TUN network interface and capture IP packets. Then I'd like to forward ...
0
votes
1answer
52 views

Redirect traffic through the server

My task is to redirect traffic (port range) through the server. Here is the schema: Why NAT is not appropriate here: If NAT is set to "Tunnel Server", then all users will be assigned the same IP. ...