Programming :: Delete The Default Gateway Via NETLINK Kernel API?
Apr 15, 2010
I am looking for a way to delete the systems default gateway from the routing table via the NETLINK API.Unfortunately, the documentation I found about NETLINK is incomplete.There are some basics (communicating with the kernel, reading the routing table) but not much more.Does anyone know the packet format for deleting a routing table entry, especially deleting the default gateway? I can set or change the default gateway with the following parameters (there are more, but I left out all the non-essential ones):
I write the network driver. Transmission of packets in user space I do through netlink socket`s. In user space there is a handling of packets and their transmission on other device (however, it isn't important).
Problem in that any time, packets through the driver in system, and is reverse, are transferred normally. But then there comes the moment when the kernel crash. If to look in syslog it seems to me that comes deadlock. Also I think that it is related with netlink socket`s.
I can't find the information on that anywhere how correctly to use netlink socket`s in kernel space. Can at you will any a reason into the account of synchronization of sockets and the driver in kernel space?
i'am tring to use generic netlink and can't find function for blocking not busy waiting receive. I'll try to explain myself. Generic netlink receive mechanism based on callback function - when module receives something,this function invoked. But this is not so good if you need to send something and receive answer. I mean something like that :
sendmsg(); if(recvmsg() < 0) goto err; I need generic netlink recv() function, or some mechanism to implement it. I just want to stay in "recvmsg()" function until i have answer(until call_back function invoked).
in fedora/redhat system I want to add IP address along with Default Gateway and DNS.For assigning IP to eth0 i use the command # ifconfig etho 192.168.1.10 subnet mask 255.255.255.0 upthis remain temporary and when I restart my system it lost the IP address. Well to permanently add IP address in etho I use the file #cd /etc/sysconfig/network-scripts and then use # vi ifcg-eth0 to add IP address and Network Mask. How can I add Default Gateway and DNS permanently in ifcg-eth0 file or there is any other file for it ?
I have installed ubuntu 9.04 Jaunty server from disk. I am connect to my corporate internet. I have put in my http_proxy everywhere I can find to put it. I am getting an ipaddress, gateway, broadcast,etc. My wired is connected. When I try to ping my default gateway it times out. %100 packet loss. I get the ipaddress of the gateway from the (route command).
My configurations on /etc/network/interfaces is correct(I am on another computer so I can't copy and paste) and I even tried updating the drivers for NIC card. I am using a Intel 82567LM-3. I have been working on this longer than I care to admit.
I'm having some difficulty with a internet/vpn setup. I have 3 network adapters on the server. 1x is used to connect it to the rest of the network 1x is used to provide internet (squid,dansguardian) 1x is used to connect to the vpn router
My interfaces file looks like this:
Code: # This file describes the network interfaces available on your system # and how to activate them. For more information, see interfaces(5). # The loopback network interface auto lo iface lo inet loopback
The problem that I have is this: When the gateway on eth2 is set to 10.0.2.2 the VPN works 100% but there is no internet. When the gateway on eth2 is set to 192.168.0.6 there is internet but no VPN.
So what I want to do is, route all traffic that is supposed to go to 10.0.2.0/24 and 10.0.3.0/24 to eth2 and all internet traffic to eth0.
I have installed eeebuntu NBR on my laptop and it looks great on a 17 inch widescreen. It looks so different from the usual interface that I get people ask about it and I can evangalise without being considered a boring weirdo! Anyway, I have one problem. Every time I boot I have to run the following command. Code: sudo /sbin/route add default gateway 192.168.0.1 How do I get this to happen automatically (as it normally does)?
Im trying to achieve the multiple uplinks/provider found on LARTC.org. I have to get the IP addresses from my interfaces (EF1 and EF2) by using a script, but i dont know where to look at for the default gateway from each interface which got their ip address from my ISP.
I have a computer with two interfaces: a fixed connection (eth1) and a modem (ppp0). My goal is to receive UDP packets from both connections concurrently (using the recv() function). The problem is, that the received packets reach the application only when the default gateway is set to that interface's address. For example, if I set the default gw to be in the eth1 subnet, only packets from eth1 reach the application. Other packets are received in the interface (checked using tcpdump), but they seem to be blocked somewhere. The policy defined in iptables is "ACCEPT" for all incoming packets, with no rules at all. I would like to know how to overcome this problem, and anyway how is the default gateway related to incoming UDP?
I have a dual-homed Debian server running squid, but not acting as a router. Simplied network diagram is below - there are other local hops between the gateways and the Internet.
Code: (eth0 @ 192.168.44.2) <--> (Gateway1 @ 192.168.44.1) <--> Internet (eth1 @ 192.168.55.2) <--> (Gateway2 @ 192.168.55.1) <--> Internet
Using Gateway1 gives a very fast, but not always reliable route to the Internet. Using Gateway2 gives a slower, but more reliable route to the Internet. The server uses Gateway1 as the default gateway.
I have written a script that pings three hosts on the Internet, and if all three are down, switches the default gateway to Gateway2. This part seems to be easy, but I'd like know if there is a way of routing a ICMP/ping out eth0 to a host, with all other traffic to the host going out eth1, so I can determine if the Internet is reachable via Gateway1 again.
I am realtively new to BGP. I use BGP in my network to advertise my /20 subnet. What i would like to know is what is the point of accepting routes from your neighbouring AS(ISP)?My ISP has given me a default gateway, and no matter what I want to reach on the internet I have to go through that default gateway, so why populate the routing table with soo many routes?also, as i understand it, there are 3 kinds of routes that you can accept, those are full routes, directly connected routes and default routes. What is the diffrence between them and again how do they affect routing since my network only has the one default gateway?
i have a leased line ( speed 2 MB ) which we use to connect to our mail server , oracle ERP etc.. we have a dhcp scope defined as 192.168.100.1-192.168.101.254. with a default gateway as 192.168.100.90 ( which is a cisco router ) we have a pix firewall ( 192.168.100.10 ).. now the gateway passed all the request to firewall..we have an ADSL of 4 MB speed.. ip is 83.*.*.230 from ISP. i have a proxy server ( squid ) eth0 is connected to ISP (83.*.*.230).. eth1 to LAN ( 192.168.100.79 ) now the problem is when i put default gateway to eth1 ie 192.168.100.90 the squid connects to internet via leased line.. if i leave the default gateway field empty on eth1 , the squid connects to internet via ADSL ( which i want ) but the problem is no one on the lan cant ping the squid server ( no connectivity to internet for the whole LAN ) how can i solve this problem? PS : i want squid to connect to internet with ADSL, but if i put gateway on eth1 ie LAN squid goes through leased line which i dont want to happen
after a reboot of my Lenny system, the default gateway will lost. Then i must try "networking restart" and the gatway will be set
my interfaces looks :
# This file describes the network interfaces available on your system # and how to activate them. For more information, see interfaces(5). # The loopback network interface auto lo iface lo inet loopback
I have a CentOS running. It is important to have my CentOS available when I am remotely connected to a VPN router. I tried to add a default gateway to the VPN router, but after reboot it goes away. How can i put this as permanent?
I had a router crap out yesterday. I'd been testing out a new one for the last few days and just reconfigured it to be the main. Took the old one down and everything in my house (Windows 7 PC, XP Files server, Ubuntu PC , windows 7 laptop, android tablet, ps3, etc) seems to be working fine whether it be hard wired or wifi. All except my ubuntu 10.04 laptop. It worked fine before the swap so I can't figure out what's going on.
I'm able to connect to the new SSID without issue but I can't resolve any external names and when I try to ping the default gate way every other packet has (DUP!) behind it. If I'm hardwired I don't get the dup! when pinging the default gateway but I still can't resolve any external names. I have provided the results of an ifconfig and the results of a ping to the default gateway below.
cooley@Quigon:~$ ping 192.168.1.1 PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data. 64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=2.98 ms 64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=3.04 ms (DUP!) 64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=3.50 ms 64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=5.72 ms (DUP!) 64 bytes from 192.168.1.1: icmp_seq=3 ttl=64 time=8.09 ms
I posted it on another forum, but could not get response,So I have this cenOS, Ubuntu and windows operating system running on virtual machines.Now I gave them manual ip address, both ubuntu and windows machines can ping the default gateway, but not the CentOS.It should forward 0.0.0.0. to my cisco router address(192.168.5.254),
I'm looking for a method to assign a default gateway via dhcp randomly depending on ether the last char of the mac being odd or even, or the time the user connects. Is there a good reliable way to achieve this?
I have installed dhcp-server on ubuntu. And server is providing ip address to clients (Window machines) but not default-gateway but I have another network in my network and same configuration and same dhcp-server provides every information.
I recently upgraded a 11.0 installation running on Xen Server to 11.3. I am experiencing frequent network disconnections now. The ip address and default gateway is assigned statically. However, the system seems to ignore the default gateway after a while. Then after several minutes it seems like it comes back.
Code: root@poe5e:~/ > route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.111.0 * 255.255.255.0 U 0 0 0 eth1 172.16.107.0 * 255.255.255.0 U 0 0 0 eth0 link-local * 255.255.0.0 U 0 0 0 eth0 loopback * 255.0.0.0 U 0 0 0 lo default 172.16.107.254 0.0.0.0 UG 0 0 0 eth0 root@poe5e:~/ > ping 172.16.107.254 PING 172.16.107.254 (172.16.107.254) 56(84) bytes of data. 64 bytes from 172.16.107.254: icmp_seq=1 ttl=255 time=0.515 ms 64 bytes from 172.16.107.254: icmp_seq=2 ttl=255 time=0.484 ms 64 bytes from 172.16.107.254: icmp_seq=3 ttl=255 time=0.496 ms 64 bytes from 172.16.107.254: icmp_seq=4 ttl=255 time=0.473 ms ^C --- 172.16.107.254 ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 2997ms rtt min/avg/max/mdev = 0.473/0.492/0.515/0.015 ms root@poe5e:~/ > traceroute orl3akm1n traceroute to orl3akm1n (10.111.19.19), 30 hops max, 40 byte packets using UDP 1 172.16.107.250 (172.16.107.250) 0.405 ms 0.398 ms 0.357 ms 2 * * *
When my sessions suddenly die and I have to coax it into routing correctly again.
Struggling to get my Linux server accept ICMP redirects not originating from default gateway. No problem to get it working if the redirects is originating from def gw.I know it's not a good solution security wise, but my network is so cluttered I'm forced to do so.
Client which uses an ISP with a Linux machine (Server 1) with two network cards. Eth0 with ip 126.96.36.199 and gateway 188.8.131.52 these ip's is not public ip's and falls unders the isp's internal range, eth1 with the internal ip range. OpenVPN listen on eth0 for incoming connections. We want to connect to Server1 from external networks. Due to different reasons the isp could not get the routing sorted and give us an public ip on his network. We had to setup another bos (Server2) with eth0 184.108.40.206 and gateway 220.127.116.11 which is public ip's and eth1 with ip 18.104.22.168. Server 2 can communicate via the ISP internal network with server 1. I use DNAT to forward all incoming connections on server 2 to server 1 but the problem I have is that server uses its default gateway for the return packages and does not sent the reply back to server 2. My iptables rules looks as follows on server 2.
I'm using OpenWRT on a WRT54GS. I'm using wifidog in combination with openvpn. For those of you familiar with wifidog, my auth server is located at the other end of an openvpn tunnel and the "wifi dog gateway" is running on the WRT itself. I'm don't really think that wifi dog is the issue. Basically, I'm using openvpn with the "redirect-gateway" option which works well. In this mode, openvpn removes my current default gateway setting and adds the remote openvpn server as the default gateway (as it should). However, overnight, my default gateway on the local network keeps reapperaing (along with the openvpn one as well).
This causes confusion and I don't want any packets (But ovbiously the connection to the actual openvpn server) to go down this local gateway. Why do you think it reappears? Do you reckon openvpn is dropping connection and somehow the normal gateway is being added back? I *could* run a cron script which runs every minute or so with something like "route del default gw xx.xx.xx.xx" (where xx.xx.xx.xx is the default gateway which I don't want to be there) but that is quite messy and means that if I were to ever move the router I would need to reconfigure this and considering that I would like in the future to have many of these wifi dog gateways, this really isn't an ideal option (as every network will have a different default gateway).
I could not able to configure the default gateway ip address onto the system. i use the route command (" route add default gw 192.xxx.xxx.xxx eth0 ") to add a default gateway onto the routing table but it is "disappear" in the routing table when i had restart the service network.