Managing and using network connectivity on a unix system

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Why tcpdump captures many packets with “(tcp-syn) != 0” but not with “tcp[tcpflags] & (tcp-syn) != 0”

I want to capture the initial handshake of a UDP connection between my computer and a VPN server. For that I'm using tcpdump but I don't understand why : tcpdump dst port 1194 and "tcp[tcpflags] &...
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0answers
8 views

Tracking traffic through a filtered intranet connection

I am performing a traceroute (I also tried a curl out of curiosity, that just stalls) on a publicly available website (so I know my computer should be able to and is allowed to reach it). However, ...
4
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0answers
100 views

Simulate a network cable unplugged without losing all routes

I want to simulate unplugging a cable from a Linux instance. My initial response was ip link set eth0 down. However, this command has impact on higher-level networking functions, e.g. routes (...
1
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1answer
13 views

debian libvirt 2 subnets

I want to create a network like this: I have a virtual host which is conntected to my physical router with eth0 and ip4 address 192.168.178.100. I create a virtual machine dmz which connects '...
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0answers
20 views

How can I have a pingable IP but the wireess interface is unassociated?

I've been installing wireless networking support on a base image and have ran into something really strange. Look closely at the output of ifconfig and iwconfig. I have a valid dhcp assigned ip from ...
0
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1answer
17 views

What do you explain my issue with if I can send an MTU packet of this size? [duplicate]

See this: Some websites load while others load forever in Linux Mint 18 And this: Is there anything suspicious in my ifconfig? Also don't forget about this: ping -c 1 -s 1500 8.8.8.8 PING 8.8.8.8 (...
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1answer
739 views

eth0 not getting disabled after setting up br0 interface

On debian squeeze, I setup a bridge based on eth0. My /etc/network/interfaces is # The loopback network interface auto lo iface lo inet loopback # The primary network interface #allow-hotplug eth1 #...
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4answers
5k views

Keep losing resolv.conf configurations [on hold]

Every time I reboot raspi, the resolv.conf file is cleaned. i normally added to this file the openDNS IPs as shown below: # OpenDNS IPv4 nameservers nameserver 208.67.222.222 nameserver 208.67.220....
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0answers
10 views

Shape traffic flowing through dd-wrt router

I am working on an experiment in which several devices connect to each other via a wireless network. I want to be able to shape the traffic between the devices, i.e., control the bandwidth, latency, ...
0
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1answer
4k views

No IP address on VMware running centos 7

I just now installed Cent OS 7 on my VMware 8 and I am not able to connect it to a network. I checked the VM network and its mapped to the physical NIC. The same setting work like charm on my CentOS ...
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0answers
15 views

Maximum number of iwlist scan results

This is a question with reference to the command line utility 'iwlist' on debian. I have a remote machine which I need to produce a list of networks in the area. I use iwlist scan and sometimes my ...
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0answers
24 views

How can I change the connection I saw in ifconfig?

It appears I have approached the problem. In Linux Mint 18 64-bit when I type in ifconfig there is enpxxx (I typed in xxx instead of real) lo and ppo and some sites load while others don't. When I ...
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2answers
2k 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, ...
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2answers
111k views

Sending messages to another user

Is there any command to send messages through the Linux shell to other people on the same network? I'm using write user and then write the message itself. But there's any command that doesn't show my ...
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0answers
45 views

Is there anything suspicious in my ifconfig? [duplicate]

I'm on Linux Mint 18 64-bit and if you check my old posts I was having problem of some sites loading and others loading forever. Below is the output of ifconfig, is there anything strange there? ...
0
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1answer
32 views

Static IP address setting failed

/etc/sysconfig/network-scripts/ifcfg-eth0: EVICE=eth11 TYPE=Ethernet ONBOOT=no NM_CONTROLLED=yes BOOTPROTO=static ...
0
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1answer
523 views

nmcli connection activation failed

I was able to create a wifi hotspot on my debian 8 install using network tab under gnome settings. I was trying to do the same using nmcli but it always shows $nmcli con up id Hotspot Error: ...
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2answers
26 views

Failover default route on primary link outage

I have 2 ISPs, and a server with two IP addresses, something like this: eth0: 161.0.0.2 eth1: 171.0.0.2 I have set www.example.com with two A records, so that I have DNS LB. App is working fine ...
2
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1answer
2k views

Ubuntu: wire network is not stable and must restart network-manager periodcally

I don't know why my wire network now is not stable. After a short time of using, maybe 30 minutes, 15 minutes or maybe just 2 minutes, my network is down. When my network is down, I must run this ...
0
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1answer
33 views

Network slowness [closed]

I am facing an issue in my project.We support an App which is hosted on a unix server. Partners try to access the same from many regions. Now some users in an region say "R" are complaining about ...
15
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4answers
43k views

Output traffic on different interfaces based on destination port

My question is basically the same as Only allow certain outbound traffic on certain interfaces. I have two interfaces eth1 (10.0.0.2) and wlan0 (192.168.0.2). My default route is for eth1. Let's say ...
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1answer
34 views

How to share a connection between two interfaces

Okay so either I am dummer then I look or there is a real problem here. Fedora 23 Interface 1: enp9s0 192.168.1.137 255.255.255.0 Wired (Internet connection) Interface 2: wlp0s20u14 192.168.10.1 255....
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0answers
31 views

Why I can not open port on redhat?

I want to host sinopia (https://www.npmjs.com/package/sinopia) on the server. My problem is I can not open port for it. Default port for sinopia is 4873. OK. Lets start sinopia and then try to ...
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0answers
22 views

Automatically to connect to open network with the highest signal strength [on hold]

How can I tell Arch to connect to whatever open Wi-Fi network has the highest signal strength? (I want this behaviour with a honeypot partition or user in case my computer is ever stolen.)
0
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1answer
2k views

scp ssh: connect to host 10.0.0.109 port 22: No route to host lost connection

I use SCP command on Debian Linux to transfer a file to my colleague via LAN. But I encounter the problem: $ scp filename.file username@10.0.0.109:/tmp ssh: connect to host 10.0.0.109 port 22: No ...
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0answers
40 views

Some websites load while others load forever in Linux Mint 18 [on hold]

I have installed Linux Mint 18 64 bit and noticed Google and Youtube and others loading flawlessly (even HD videos play) but some sites like Wikipedia don't show up even though the tabs in Mozilla ...
0
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1answer
26 views

Network unreachable

Just did a fresh Arch install but when I ping 8.8.8.8 it says connect : Network is unreachable. I saved iptales rules in /etc/iptables/iptables.conf but they won't load at startup. ip a says that my ...
0
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2answers
23 views

if a HTTP request is like HTTP://IP/path with a http proxy, will it go to Internet or Ethernet [on hold]

AWS enterprise VPC http proxy exists Without the HTTP proxy, curl http://169.254.169.254/lastest/meta-data successful, but disconnect to the Internet. This IP address is not Category A, B, C. Use ...
0
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1answer
22 views

Why do I have more packets than bytes? [on hold]

I don't know how to explain this. mind blown. ip -s link 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000 link/ether RE:DA:...
7
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4answers
671 views

OpenSSH - map aliases in ~/.ssh/config to IP addresses in command line

Is it possible to query ~/.ssh/config in the command line? Let's say I would like to retrieve what IP address does the particular alias point to in a separate program, is it possible?
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3answers
2k views

tcpdump doesn't appear to be capturing any data, why?

I'm trying to capture data with tcpdump like so: $ sudo tcpdump -Xi eth0 I have the device and the PC connected to each other. On both sides I launch a simple test application that sends a message ...
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0answers
35 views

How to determine how much time a process is blocked waiting for networking (socket) activity?

We are having issues with high load (top and uptime) but high CPU idle. Usually, that means high IO wait but that's also low. I believe IO wait typically does not include time a process is blocked ...
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3answers
50 views

Lost in the world of VPN

The Q. If i have a server, is it possible to have that server with a VPN connection, while simultaneously having an entirely separate connection to be able to SSH to from client machine. The Why. I ...
4
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1answer
75 views

How can I know which IP address of a host is reachable from another?

I don't particularly need a "solution" to something, I'd just like to understand more of the landscape here. So on my CentOS box, I installed a CentOS VM specifically for learning Puppet. When the ...
3
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2answers
1k views

Wait for a network device to come up before bringing another network device up on boot?

I'm in the middle of setting up my Raspberry Pi running Raspbian as a bridge between my university's wireless network (which requires WPA2-Enterprise authentication) and my private wireless router (...
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0answers
18 views

No connection on Debian with “USB ethernet” (mobile phone sharing 3G)

I just installed debian on my amd64 PC and I need the 'build-essential' pkg to make my wifi drivers...So the only solution I found is plug in my phone and share my data connection. Nevertheless I ...
0
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2answers
859 views

two NICs in the same subnet— need to set up routing

I have a tricky case: +---+ +----+ |D1 +->eth0---------<-eth0-+D2 | | | | | | +->eth1---------<-eth1-+ | +---+ +--...
0
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1answer
14 views

Route traffic for a single IP out of eth0, the rest out of wlan0 [duplicate]

I have my laptop connected to an internal network on eth0 and an external network on wlan0. How can I configure my routes to forwarded all traffic for 10.1.1.1 out of eth0, and everything else out of ...
0
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0answers
20 views

Bridged VirtualBox VM: Is there an internal Host IP address

I'm running a VirtualBox VM in bridged network mode. Is there still an internal IP address for the Host? (I don't want traffic to my host going over the bridged network) To clarify, I do want my VM ...
0
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1answer
14 views

XYMon-Client status not showing in XYMon Server

I have installed XYMon server successfully, but I can't get the client information to show. It took me a while to figure out, but if you add a host to the server that doesn't have the client, it still ...
0
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0answers
12 views

Detect / log network changes in rasbian/ linux

I just stated using raspberrypi, Trying to learn some networking and linux stuffs. I want to log or detect network changes like If my machine joined a network. If any device joined the network of ...
0
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0answers
19 views

Apt-get update/update manager downloading slow [closed]

I am running Linux Mint 18 and my sudo apt-get update/update manager speeds were fine until today. Now they can't even get past 60 kiBs, I have tried changing servers but it was in vain, as all of the ...
0
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0answers
31 views

Outgoing network connections fail, incoming ssh login delayed [closed]

I'm having the following trouble with outgoing connections in CentOS: yum cannot connect (just hangs on "Determining fastest mirrors") Could not retrieve mirrorlist http://mirrorlist.centos.org/?...
4
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1answer
3k views

Networking and Samba from a quest OS running on qemu

I'm trying to test some software on a big endian system to ensure compatibility. My plan is to use qemu on Ubuntu 12.04 to emulate a MIPS system. So far I've been able to create the quest system ...
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3answers
6k views

Cannot access to web server, but can ssh to it

I have a Ubuntu server but there are some weird things I can't understand. I cannot ping to the server via IP address, but I can ssh to it. I can access to apache server inside the server via command ...
21
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3answers
14k views

Limit outgoing bandwidth on an specific interface

I would like to know the easiest way to limit outgoing bandwidth for an interface. I want to cap the outgoing port speed so that file transfers between my servers don't fail during busy hours. What's ...
1
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1answer
44 views

Is it possible to ping 8.8.8.8 from two interfaces connected to diffrent WANs

I'll start by explaining the situation. I started My project using a raspberry Pi 2 model B and installed Fedora Arm on it. My current Goal is to be able to connect the pi to internet through an ...
1
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1answer
1k views

cannot ping my computer on local network

I am running on 64 bit OpenSuSe 13.2 with Gnome 3 desktop environment and unsuccessfully trying to set up Samba Server. I have another computer running windows 8.1 from which I am pinging the ip ...
1
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3answers
52 views

Dnsmasq points nonexistent subdomains point to local IP

There's a specific remote subdomain mymachine.home.com whose the IP changes on all the time that I need to update DNSMasq to have it resolve correctly. But I tested pinging xxxxxx.home.com which ...
0
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1answer
21 views

Why is it taking so long to establish a LAN connection on boot?

I have an issue with a virtual machine taking time to connect to the local network on boot. I create a virtual machine using the following command: virt-install \ --connect qemu:///system \ -...