The ip tag has no wiki summary.
25
votes
2answers
2k 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
2k views
Why doesn't Linux use the IANA Ephemeral port range?
According to Wikipedia
The Internet Assigned Numbers Authority (IANA) suggests the range 49152 to 65535 for dynamic or private ports. Many Linux kernels use the port range 32768 to 61000.
Even ...
11
votes
5answers
3k 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?
9
votes
3answers
778 views
Parsing log files for frequent IP's
So, I hacked this together while undergoing a DDOS attack to pull naughty ips out of my logs. Anyone have any improvements or other suggestions to make it better?
Here's the general idea:
pull ...
7
votes
3answers
2k views
What's the last number in this ip address?
An IP address like this 223.248.0.0/24 or 223.248.0.0/16
What's the last number mean in the IP address (24 or 16 in the above example)? Is there a simple way to understand how to set the number ...
7
votes
2answers
500 views
How can I disable TCP/IP for an Ethernet adapter?
I have CentOS 6.3 running in a (virtual) machine with two Ethernet adapters. I have eth0 connected to a TCP/IP LAN and eth1 connected to a DSL modem. The system is intended as a dedicated ...
7
votes
4answers
5k views
How to find the IP address of a KVM Virtual Machine, that I can SSH into it?
I have follow this guide (Virtualization With KVM On Ubuntu 11.10) to setup my KVM (Virtual Machines Software) on my Ubuntu 11.10 Server. However, I didn't setup my VM's IP address when creating the ...
6
votes
2answers
716 views
Measuring internet connection quality
I'm having WLAN trouble on my dualbooting win/linux laptop - the connection on linux side has occasional trouble, and seems somewhat slow and chunky. I would try to fix this issue by fiddling with all ...
6
votes
5answers
371 views
Assigning IP address to environment variable
How can I assign the IP address of eth0 to an environment variable, say $ip, as easily as possible?
Update: Distro is Ubuntu Server 12.04 LTS.
6
votes
1answer
707 views
Linux always send ICMP redirect
I have several Debian Squeeze (6.0.6 up to date) used as routers.
When a link is down, they send ICMP redirects to local hosts. This is the default behaviour of Debian and several others. So once the ...
6
votes
1answer
298 views
Load Balancer Solution with linux
I need a suggestion to realize a proper solution to this problem:
As you can see in the image above, I have 2 application servers that need to talk with and external third party provider over the ...
6
votes
3answers
312 views
SpamAssassin Under Linux VPS
I am getting bald with this guys:
On a Linux VPS (CentOS), I have setup a mail server (Exim+Dovecot+Clamav+SpamAssassin) but scanning mail for spam using SpamAssassin is proving to be a challenge.
I ...
5
votes
3answers
2k 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 ...
5
votes
2answers
351 views
Change linux remote host *primary* IP address without losing control
I was wondering about how one could change a remote host primary IP address without getting disconnected at all (without being in a "no IP addr" state).
The matter is poorly discussed on Internet ...
5
votes
1answer
843 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.?
4
votes
3answers
686 views
How can I get the netmask from an IP address?
How do I get a netmask from the IP address? Is there a command to get it?
4
votes
3answers
4k views
How to find out if Ubuntu is using DHCP (Ubuntu 12.04 LTS GUI)
How can I find out if my IP address is DHCP, Fixed or Dynamic?
I need to tell my network administrator what the IP address is, that my Virtual Machine is using. I know the numbers, but I don't know ...
4
votes
2answers
1k 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
2answers
786 views
How to build a gateway from my Linux OS
I want to configure my Linux so that it will be used as a network router (gateway). Can anybody give me some hints on this? (links are welcome!)
Thanks.
4
votes
5answers
6k views
How to route specific adresses through a tunnel?
There are certain websites/services which I can only access from the subnet on which my server is located (think of the typical intranet scenario). Is there a way to transparently route traffic that ...
4
votes
2answers
243 views
How can I use one network port for VPN and the other for everything else?
My Linux machine has two network ports with two IP addresses. I want to use one port for my VPN and accounting, and the other port for other usages. How can I tell Linux not to allow any requests from ...
4
votes
2answers
777 views
What tools do I need to intercept and change an incoming packet on a WP2-Personal wifi hub
Which tools should I research into to intercept a plain text packet, edit it and then continue it on it's way. I am using Ubuntu 11.04 and Backtrack 5; my wifi is WPA2-person encrypted. I need to edit ...
4
votes
2answers
633 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 ...
4
votes
3answers
7k views
Why are my two virtual machines getting the same IP address?
I have two virtual machines both running on a Linux host (Fedora 16). I set both adapters as attached to NAT. When I boot them up they both have their default gateway set to 10.0.2.2. They also ...
4
votes
3answers
2k 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 ...
4
votes
2answers
415 views
How to configure Linux to use DHCP or static IP depending on presence/absence of DHCP server?
I would like to configure a network interface to make use of DHCP if a DHCP server is present on the network during boot, but otherwise default to some default static IP address.
4
votes
2answers
129 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?
4
votes
1answer
293 views
Control source address for whois queries
is it possible to execute the command "whois" and choose the outgoing ip for the query?
I have mounted several IP's on my network interface "/etc/network/interfaces" for ssl porpuses, but would be ...
4
votes
1answer
187 views
Inserting a nat solution into a network while it's not the gateway
I have tried this a few different ways. Currently trying with pf on freebsd 8.2
I am trying to insert a nat solution into an existing network that will redirect traffic from an outside ip address to ...
4
votes
1answer
841 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 ...
4
votes
2answers
140 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.
...
3
votes
3answers
2k 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 ...
3
votes
6answers
410 views
Find my computer on a LAN network
Let's say that I have a computer plugged in to a local network using a dhcp connection, so it will get a different IP every time. Is there a way to find this computer (so the IP) from a different ...
3
votes
2answers
203 views
Ethernet Sniffing Embeded Device
I recently dug out some prototyping equipment from the trash and I want out figure out what the heck it is. It has a port labelled 'Ethernet' and when I plug it into a router the lights flash like its ...
3
votes
3answers
656 views
Accessing a linux machine with a name (not ip address)
When I access a linux machine with sshfs, I take the following steps.
Get the ip address of the linux (the ip address is dynamically allocated to linux)
Run sshfs id@ip_address:/HOME_DIRECTORY
Can ...
3
votes
1answer
196 views
What is the GNU/Linux equivalent of BSD's “route get …”?
The BSD route command has a feature that will show what route will be selected for a given host. For example:
/Users/mhaase $ route get google.com
route to: iad23s07-in-f8.1e100.net
destination: ...
3
votes
1answer
223 views
Route incoming network requests for a given port to different applications
I have an application that listens for connections on a port, but I occasionally take it down for updates and the like. I'd like a way to configure the system such that if that program is running, ...
3
votes
4answers
1k views
Sniffing packets through router
I would like to create a system like this.
The user would connect through a wifi network which would reroute all http requests and responses through the network card on a computer thus allowing that ...
3
votes
2answers
145 views
How to force a connection to a certain host to use to a specific source IP?
When using the Shoutcast2 yellowpages there is a really annoying issue that it always uses the default IP the system uses for an outgoing conection to register itself even if the server is configured ...
3
votes
1answer
140 views
is it possible to send the remote connector ip via netcat?
Actually I want to make something like ifconfig.me functionality but only for my internal network. I see it the way smth on server listens some port and send ip of connected remote machine.
Seems nc ...
3
votes
1answer
485 views
Two IP addresses assigned to the same machine?
I seem to be using two IP addresses on my PC. I use DHCP to get an IP address and then I statically set an IP address and activate it. ifconfig says that I am using the address given by DHCP but I am ...
3
votes
1answer
1k views
avoid IPv6 link local address on interface
I have a setup with virtual Xen hosts connected to a set of VLAN-s. On Dom0, I have set up a bridge for each of my VLAN-s to connect DomU-s to. Bridges are set up in /etc/network/interfaces like ...
3
votes
1answer
207 views
set VM IP address to be the same every time from DHCP on CentOS 5.6
I have an issue where, each time I start my CentOS 5.6 VM, DHCP (I believe) is allocating my VM a different IP. I have the VM mapped as a Samba share in Windows 7 and this changes between 192.168.0.8, ...
3
votes
1answer
234 views
Kickstart: one network card with DHCP, one with static IP?
I am using Kickstart to automate a CentOS install. I wanted one of the interfaces to have static IP so I wrote -
network --onboot yes --bootproto static \
-ip="intended IP" -netmask="intended ...
3
votes
2answers
639 views
IP rule for IPv6
When I try to add an IP rule for IPv6 on my Linux system, it errors out:
$ ip -6 rule add fwmark 0xfab lookup 0xf
RTNETLINK answers: Address family not supported by protocol
I checked out the IP ...
3
votes
1answer
233 views
What is the kernel doing when I bring a TUN/TAP interface up
I'm playing around with the TUN/TAP device on Linux.
I've created a simple program that creates a TAP interface and prints anything that is sent through it.
When I bring the interface up with
ip link ...
3
votes
1answer
114 views
Labeling/Aliasing multiple network addresses
If my machine is connected to several networks and configured with multiple addresses (ipv4), is it wise to configure and use labels to identify them ?
By labels I mean the iproute2 ip command's ...
3
votes
1answer
187 views
Detecting multihomed machine
Is there a way to reliably detect whether or not a machine is multihomed? I'd like to be able to write a script that will return a true or false regarding that information. Thanks.
3
votes
1answer
531 views
How to set a static IP in Ubuntu
How do I set my computer to have a static IP in Ubuntu 11.04? The only two lines in /etc/network/interfaces are:
auto lo
iface lo inet loopback
I think usually when people do this they have a wired ...
3
votes
1answer
76 views
Alternative to mrouted for DVMRP on Debian Squeeze
I need to implement DVMRP protocol to route multicast over Openvpn (tun) connection for some old 3Com NBX phones.
I use Debian squeeze so mrouted is not available (obsolete).
What can I use ...
