the IP protocol and IP addresses

learn more… | top users | synonyms

9
votes
3answers
4k views

Can't access select https sites on Linux over PPPoE

My internet connection used to be a direct LAN connection to my provider. Back then, everything would load fine on both Windows and Ubuntu (dual boot). However, a while ago they started needing me to ...
87
votes
19answers
75k views

How can I get my external IP address in bash?

I need to find my external IP address from a bash script. At the moment I use this function: myip () { lwp-request -o text checkip.dyndns.org | awk '{ print $NF }' } But it depends on ...
20
votes
9answers
22k views

How to get my own IP address and save it to a variable in a shell script?

How can I get my own IP address and save it to a variable in a shell script?
4
votes
2answers
17k views

Set Static IP in CentOS 6.4?

Most guides seem to revolve around modifying ifcfg-eth0, which doesn't exist on my system.. [root@Azaz07]# vi /etc/sysconfig/network-scripts/ifcfg-eth0 [root@Azaz07]# ls ...
3
votes
1answer
840 views

Route SSH to host through interface

Is it possible to route all outgoing requests for SSH (port 22) to mydynamicdns.afraid.org via wlan0 instead of eth0 when both are connected? Since my IP is dynamic, I would like to use a name ...
17
votes
2answers
5k views

Is there an easy way to programmatically extract IP address?

Is there an easy way to programmatically extract IP address, without tedious parsing of ifconfig? I would not mind simple command output processing using sed to do it but not processing multiline ...
5
votes
2answers
3k views

Routing for multiple uplinks/providers

I have a PC with two internet connections. The first one is an Ethernet interface to connect to my local network and access internet via my router. The second one use a GSM modem to connect with ppp. ...
4
votes
3answers
4k views

Send duplicate packets over two Internet connections

I need to duplicate an RTP stream over two different (non-reliable) Internet connections. On the receiver side, I will probably run a custom program that will use a buffer and rebuild the stream ...
5
votes
3answers
4k views

How to filter IPv4 and IPv6 addresses?

echo "1.1.1.1" | awk '/[0-9]*\.[0-9]*\.[0-9]*\.[0-9]*/ {print $1}' How can I filter IPv4 addresses in a script, and how can I filter IPv6 addresses. I mean more precisely then this so the oneliner ...
6
votes
3answers
12k views

Find out network traffic per IP

We have one central server which functions as an internet gateway. This server is connected to the internet, and using iptables we forward traffic and share the internet connection among all computers ...
49
votes
2answers
6k views

How does SSH connection survive a network restart?

From a Linux SSH shell, type /etc/init.d/network restart to restart the network service. I expect my SSH connection to die since the network service goes down. But it doesn't. Very cool. But how does ...
15
votes
1answer
6k views

Is it better to set -j REJECT or -j DROP in iptables?

There's an example of iptables rules on archlinux wiki: # Generated by iptables-save v1.4.18 on Sun Mar 17 14:21:12 2013 *filter :INPUT DROP [0:0] :FORWARD DROP [0:0] :OUTPUT ACCEPT [0:0] :TCP - ...
5
votes
2answers
3k views

How to know if a network interface is tap, tun, bridge or physical?

As far as i know, there are 4 main types of network interfaces in linux: tun, tap, bridge and physical. When i'm doing sys admin on machines running KVM, i usually come accross tap, bridge and ...
12
votes
1answer
17k views

What is kernel ip forwarding?

I have seen on many blogs, using this command to enable IP forwarding while using many network security/sniffing tools on linux echo 1 > /proc/sys/net/ipv4/ip_forward Can anyone explain me in ...
16
votes
3answers
4k views

IP to Country console command

Is there a console command that takes an IP address as an input and shows its geographical information like city, country, ISP, etc.?
7
votes
3answers
4k views

Difference between 'ifconfig' and 'ip' commands

I read some articles/tutorials on 'ifconfig' command, most of them included a common statement - "ifconfig is deprecated by ip command" and suggested to learn ip command. But none of them ...
9
votes
1answer
550 views

Send a packet over the network even when its target is the local host

Under Linux if you send a packet to the address of one of its network interfaces, this packet is routed internally, it is never sent over the network. That's the right thing in 99.99% of the cases. ...
6
votes
2answers
893 views

Static IP for 2 PCs on crossover cable in interfaces(5) file?

I've got 2 PCs connected on an Ethernet crossover cable. On PC1 I run: sudo ip addr add 192.168.2.1 peer 192.168.2.2 dev eth0 sudo ip link set dev eth0 up On PC2 I run: sudo ip addr add ...
5
votes
2answers
5k views

Discover MTU between me and destination IP

In a case I can use only UDP and ICMP protocols, how can I discover, in bytes, the path MTU for packet transfer from my computer to a destination IP?
5
votes
2answers
3k views

Can't ping broadcast

We're running four computers connected to a hub (yes a hub not a switch) on Fedora 13. They were installed using images from a colleague that has recently left us to go back to school, they may have ...
4
votes
1answer
2k views

multigateway routing for specific src port

I have two gateway to access internet, somehow I want to load balancing it, so far its working, but some connection or service need persistent gateway IP to be used, so the client should never change ...
3
votes
4answers
12k views

IP of localhost

How does a Linux instance determine its IP address? That is, not the 127.0.0.1. Is this stored in file or does ifconfig somehow calculate it at every invocation? I managed to solve it just to show ...
4
votes
1answer
562 views

Why is this static route not taking effect?

Original Question I am running Ubuntu and network manager. I have two different interfaces, eth0 and eth1. Network manager has (as far as I can tell) correctly added this manual route: ~$ ip route ...
2
votes
4answers
15k views

SSH is suddenly not working anymore: “Write Failed:Broken Pipe”

I use a macbook pro at home and regularly ssh into the machines at my lab. For the past 3-4 days however, whenever I SSH into the machine in the lab, I get a Write Failed:Broken Pipe error, hardly ...
3
votes
1answer
69 views

Bash: Permission denied when trying to echo data directly to Network

I am trying to send characters directly to the network stack as explained in this thread. Even when the process work OK under CygWin (Windows), the same lines do fail on Ubuntu v14.04: ...
3
votes
0answers
59 views

delay in IP route deletion

(Apologies if this is the wrong StackExchange for this question, but there does seem to be some confusion regarding appropriate targeting of IP networking questions) I am very much a network newbie, ...
2
votes
1answer
544 views

how to check if the kernel support for ip alias?

it surprisingly that I get no explicit results when I googled "kernel ip alias support", and I have looked up the linux network administrator, 3rd edition, it says: check that you have a ...
2
votes
3answers
1k views

What are the interface prefix meanings in ifconfig?

I'm not sure if these have a name, but on most computers I use the interface prefixes are usually: eth- : Ethernet/Wired wlan- : Wireless/WiFi However, on my ASUS RT-N56U, I have the following: ...
2
votes
1answer
2k views

Static IP address shifting to 192.168.1.251

I have a system with a static IP address of 192.168.1.150. I configured /etc/network/interfaces manually (i.e. without using NetworkManager.) It is a web server hosting three sites. I am having ...
1
vote
0answers
45 views

No “rwnd” option to “ip route” for managing the receive window?

Context: I'm doing some self-guided studying on TCP Window shaping. The scenario I'm trying to control for are clients which will be pulling down large amounts of data in addition to their normal ...
1
vote
3answers
336 views

Enabling IP forwarding at kernel compile time

I am compiling a kernel for a router. I know a way to enable IP forwarding in an existing Linux system. At compile time, CONFIG_IP_FORWARD is said to do the same task. I am configuring version ...
1
vote
1answer
422 views

Unable to get embedded device to ping anything on the network

I have an embedded device, built using buildroot, kernel version 3.6.11 running busybox. The kernel is built with completely default options. I have configured the device according to what the network ...
0
votes
2answers
2k views

How to generate random IP addresses

$ nmap -n -iR 0 -sL > RANDOM-IPS-TMP.txt $ grep -o "[0-9]*\.[0-9]*\.[0-9]*\.[0-9]*" RANDOM-IPS-TMP.txt | egrep -v "10.*|172.[16-32].*|192.168.*|[224-255].*" > RANDOM-IPS.txt egrep: Invalid ...