Fedora Networking :: Raw Packet Creation - Sending Specific DHCP Offer?
Jan 25, 2011
I am trying to design an application which violates the DHCP. Specifically the difficulty in writing this application is physically sending the raw packet. I need some documentation on either a library that supports this or where to look for support for raw packet creation. I am not trying to create a raw datagram, that doesn't meet my needs because a raw datagram is still at layer 3 I need to craft a raw layer 2 PDU.
Specifically I want to
Send a very specific DHCPDISCOVER
Receive a DHCPOFFER
and pull apart the offer while never sending a DHCPREQUEST.
Specifically I am pulling apart various options that are sent in the DHCPOFFER. I have a raw DHCPDISCOVER already crafted and the formatted struct sockaddr_ll where I fault is I can't send the damn thing. Getting the file descriptor after calling socket is okay but what now? How would I write to that file descriptor and have it transmit?
Code:
int connfd;
struct sockaddr_ll bcast;
bcast.sll_family = PF_PACKET;
...
connfd = socket(PF_PACKET,SOCK_RAW,0);
//now what
eth0 is configured through a dhcp server connected directly to it. [URL]...the answer of the server is a UDP to 255.255.255.255. Please tell me how can it pass through this iptables configuration, because it does.
Code: iptables -nvL INPUT (policy DROP) 3281 201K ACCEPT all -- eth1 * 192.168.69.0/24 0.0.0.0/0 0 0 ACCEPT all -- lo * 127.0.0.1 0.0.0.0/0 0 0 ACCEPT all -- lo * 192.168.69.1 0.0.0.0/0 0 0 ACCEPT all -- lo * 93.114.xx.xx 0.0.0.0/0
I'm implementing static IPv6 address on two Fedora 13 installed hosts. These two computers are connected using a switch between them and I use D-ITG to generate traffic in the network.I need to send packet from host1 to host2 using this command and I got permission denied
Code: #./ITGSend -a 2001:db8:c003:111e::3 -T UDP -x recv_log_file -t 30000 -c 32 Connect error in createTransportChan(): Permission denied
In order to debug a problem, I want to list down as many as possible reasons of a server (SOAP server running on Fedora 10) sneding RST in middle of packet transfer. Please note that in my case, SYN and ACK of initial handshake went through. Server received request from client and started data transfer but then suddenly, server sent RST in between data transfer.
we have a minor issue with time synchronization in proprietary equipment.the client needs to synchronize time with server, but not using NTP.it is not very important so doesn't need to be done often.the problem is that it won't synchronize. I can see the server is sending tcp packet with date&time, but the client ignores it.I suspect the problem is in format (manual specifies there are two possible options like MM: DD: YYYY and so on, but server seems to use some other)Is there an easy way to run some program in Linux Debian, to send that simple packet with correct date?
This is probably an odd request, but figured I'd ask in case someone knew. We have a lab that has the IP range 172.10.0.0/16 (255.255.0.0). The lab gateway/DHCP assigns an IP in the range of 172.10.0.2-172.10.0.254. I want to set up my own DHCP server on a specific range, for example 172.10.10.1-172.10.10.254. I create a new host fine, but since it's set for DHCP, it uses the DHCP server at 172.10.0.1. Is there a way to force it to use a different DHCP server on the client side? I realize that I can work around this with exclusions on the 172.10.0.1 DHCP server, or use iptables to deny DHCP requests to specific MACs, but wanted to know if there was an (easier?) way to configure the client to use the 172.10.10.1 DHCP server instead of the 172.10.0.1 server?
I want to setup 1Gbps our lab network and we purchased 'Buffulo Giga layer switch ' with 24ports. Is there a way to tell DHCP to assign specific IP to a particular MAC address of a machine ? We want to use DHCP and whatever the port we use ,it should have same IP ..
I am the new user to ns-2. I would like to know is it possible to send the keys or some value as the packet data (content of the packet) in ns-2 (for wireless environment).
I wrote a program for transmitting an UDP Packet. It is properly received in Fedora core 2 machine while its not received properly in Fedora 12. I tried using Wireshack packet capture software which shows the protocol as DIS. Is there any service or setting i need to do for identifying the packet as UDP.
I'm running gnome desktop on squeeze system. When I boot my system seems to be using my internet modem as its dhcp server. The rest of the machines on my lan are correctly using my router for that purpose. As a result, what happens then is that my debian machine frequently gets a duplicate ip address assigned to it. I would like to specify to my debian computer that I want it to use the specific fixed ip address of my router for dhcp purposes.
Now, every time I do yum update my system will also offer me package for F12, F13, F14. But if I try to install it, it will not resolve because I my system is still F11. I don't remember exactly what the error message is, but I think it said that I should have system > 13 to install that packages. What should I do so next time I do yum update I just offered packages I needed only?
I have written the Client-Server program to test my ethernet by using UDP protocol. Server IP : 192.168.0.254 Client IP : 192.168.0.1 While Running the program I am getting some printk messages on Server machine.
What is the meaning of following statement that I am getting from debug statements ( /var/log/messages ) UDP: short packet: From 192.168.0.1:43898 418/416 to 192.168.0.254:7000 printk: 5 messages suppressed. UDP: short packet: From 192.168.0.1:43898 556/553 to 192.168.0.254:7000 printk: 4 messages suppressed.
Only printk messages are printing in my Server console ( IP : 192.168.0.254 ). printk: 5 messages suppressed. printk: 5 messages suppressed. printk: 4 messages suppressed. printk: 2 messages suppressed. printk: 4 messages suppressed.
I have some beginner questions about DHCP, Avahi, and configuring a small home LAN.Suppose I have a dynamic IP address assigned by my ISP, which requires DHCP be enabled in my dsl modem/router/"firewall" [sic]. Suppose for simplicity I have just one PC behind the dsl modem.I think "enabling DHCP" in the modem/router means that a DHCP client runs on the router, which communicates with a DHCP server run by my ISP when I boot up a PC on my LAN. Is that guess correct? Can I get DHCP to assign a particular local IP, say 192.168.1.10 (which is not the one taken by the router--- for this discussion, let's say that is 192.168.1.0) to my PC each time I boot it up?
Now suppose I want to build a stand-alone firewall, so that my LAN will have the firewall and the first PC behind the modem, with the first PC virtually behind the firewall. By default, I think these will both have DHCP clients running which I need to configure properly. The firewall should also have a DHCP server which should control how local IP addresses are assigned, correct? I should try to arrange that the LAN has only DHCP server, only one NTP timeserver, only one DNS nameserver, correct?My first PC seems to have installed an autorun client called Avahi, which performs DNS multicast services and incorporates something called zeroconf which seems to have something to do with remote desktops, which I don't need and which is a potential security hazard. But it seems that Avahi is an intrinsic part of the KDE desktop and cannot be removed. Just want to be sure that Avahi can coexist comfortably with dhcp3-client, which is also installed on that PC. They perform different tasks, correct?If I can get the stand-alone firewall to work, I know I need to turn off the commercial firewall in the dslmodem/router/firewall device. Should I purchase a bridge and try to turn off the routing function also?
Back in April I set up a Ubuntu DHCP server and a multiple VLAN network [URL] to migrate our various servers, workstations, etc off the 192.168.1.1 /24 network that everything was on because we where running out of address space. I built out the new network and everything worked great except our AD server would never get an IP address from the DHCP server (static reservation) and even if I set the IP statically on the AD server it couldn't ping the gateway and noone could log in. After several attempts to resolve this, including bringing in outside help, we where never able to figure out what the problem was.
Now 6 months later I have time to revisit the issue without effecting the live network. I used Acronis and imaged the AD server last Friday, cloned it on to another box with the same hardware, and put it up on the new network that's been sitting unused for the last 6 months. Today when I statically set the IP on the AD server (which is what I want) it connects and I can ping it's gateway 192.168.1.1 and all the way across vlans to a test sales agent workstation at 192.168.8.xxx on vlan 800 but only if I statically assign the agents station an IP address. When I try to get an IP address via DHCP it fails as destination unreachable. Nothing has changed in the last 6 months on the DHCP server but now it for some reason can't ping its default gateway 192.168.1.1. All of the config files are the same as they where left from the post linked above aside from the vlan id's used where changed from 1's to 100's (i.e. vlan 3 is now vlan 300) /etc/network/interfaces
Code:
auto lo iface lo inet loopback auto vlan100 iface vlan100 inet static
[code]....
why it can't reach the gateway, when I do a tcpdump I can see the DHCP requests come in on eth0 but the server never responds and I'm pretty sure its because it isn't "seeing" them since it thinks there isn't a network connection but I don't know how to trouble shoot to find out where the problem lies.
Back in April I set up a Ubuntu DHCP server and a multiple VLAN network [URL] to migrate our various servers, workstations, etc off the 192.168.1.1 /24 network that everything was on because we where running out of address space. I built out the new network and everything worked great except our AD server would never get an IP address from the DHCP server (static reservation) and even if I set the IP statically on the AD server it couldn't ping the gateway and noone could log in. After several attempts to resolve this, including bringing in outside help, we where never able to figure out what the problem was.
Now 6 months later I have time to revisit the issue without effecting the live network. I used Acronis and imaged the AD server last Friday, cloned it on to another box with the same hardware, and put it up on the new network that's been sitting unused for the last 6 months. Today when I statically set the IP on the AD server (which is what I want) it connects and I can ping it's gateway 192.168.1.1 and all the way across vlans to a test sales agent workstation at 192.168.8.xxx on vlan 800 but only if I statically assign the agents station an IP address.
When I try to get an IP address via DHCP it fails as destination unreachable. Nothing has changed in the last 6 months on the DHCP server but now it for some reason can't ping its default gateway 192.168.1.1. All of the config files are the same as they where left from the post linked above aside from the vlan id's used where changed from 1's to 100's (i.e. vlan 3 is now vlan 300) /etc/network/interfaces
Code:
auto lo iface lo inet loopback auto vlan100
[code]....
why it can't reach the gateway, when I do a tcpdump I can see the DHCP requests come in on eth0 but the server never responds and I'm pretty sure its because it isn't "seeing" them since it thinks there isn't a network connection but I don't know how to trouble shoot to find out where the problem lies.
I am puzzled with trying to configure a linux (openSUSE) client to dhcp to eBox DHCP server. I am using dhclient to lease an IP address with dhclient eth0 -s 10.45.48.108 and get a response
openSUSE11232CL1 dhclient: DHCPDISCOVER on eth0 to 10.45.48.108 port 67 interval 4 openSUSE11232CL1 dhclient: DHCPOFFER from 10.45.48.108 openSUSE11232CL1 dhclient: DHCPREQUEST on eth0 to 10.45.48.108 port 67 openSUSE11232CL1 dhclient: send_packet: Network is unreachable openSUSE11232CL1 dhclient: send_packet: please consult README file regarding broadcast address.
The server reports eBox141 dhcpd: DHCPDISCOVER from 00:0c:29:3e:57:a3 (openSUSE11232CL1.domain.net) via eth0 eBox141 dhcpd: DHCPOFFER on 10.45.200.2 to 00:0c:29:3e:57:a3 (openSUSE11232CL1.domain.net) via eth0
I interpret this as the server receives the request and the client accepting it but the lease does not last long and the connection breaks. what this could be and why the connection breaks? Or my undestanding is totally wrong on how it works and should work? And BTW, where is that README file that's referenced in the message I receive on the client?
I've been running 10.04 since September on my new MSi i3 notebook and about two weeks ago I noticed that when I login after system boot, propagation of icons on my desktop and the content of my Panel have become slower and slower.If I logout and login again the propagations are not slow.
Currently I have my eth0 interface getting a DHCP address but at times the DHCP server will not be reachable. Sooo what I would like my server to do is if it cannot find a DHCP server assign a static address to eth0. Then start the DHCP service so it can then dish out some addresses.How can I do this? Surely it is possible
I have a laptop (running Fedora 10 KDE version) and a desktop (running Ubuntu 7.10) on my home network. Is there any way to send messages from one computer to another through LAN ?
I am recently trying to get a steady wireless connection running. I am currently using the default settings/driver Fedora 13 is stocked with. As my internet browsing is somewhat up and down in load times, I decided to check in a video game which is generally a good test for me. haha I am harshly spiking and cannot find the source of my problem so my guess is a driver issue.
lspci | grep Network:
Code:
Code:
It is is seemingly right, my Windows 7 harddrive works just fine, this is just one last of the few issues I'm having from fully formatting my winblows HD to use as Linux storage.
I cannot find any native AR5008 Linux Drivers for my card and it has been a frustrating day. I guess I'm not cut to be a network analyst just yet.
System specs: ASUS P5Q SE/R Intel Core 2 Quad Q9550 4GB DDR2 667 Gigabyte GTX465 1G TP LINK TL-WN851N Wireless card
I want to run networking on my laptops in different environment (home, office, airport etc). I found that Netowrk Manager assigns information from DHCP although I requested fixed IP and configured the gateway and DNS. If I reconfigure the DHCP server so that there is no free IP address, the laptop refuses to connect. When I remove the interfaces from the network manager, I get the fixed IP address, /etc/resolv.conf is not overwritten from DHCP but WiFi connection cannot be established, there is no dialog for setting WPA-PSK. The static IP address seems to be taken into account only if the DHCP server is not found. I need the static address at home and in my office because I need the possibility to ssh to my laptop from another computer but I need IP from DHCP possibly authenticating against RADIUS (Eduroam) when travelling somewhere else. Is there an easy way how to achieve it and how to switch profiles easily? And I cannot switch DHCP off because some devices in my LAN cannot work without it.
I need to know how to configure automate sending sms if server reboot and shutdown? Now i just set sms notification once my server it's UP by create scripts in /etc/rc.d/rc.local while booting then from server sending sms notification. SMS - using gnokii attached mobibe phone. Server - Fedora 10
I got a problem with my CentOS server. Somebody told me OpenVPN Requires different changes inside my firewall settings. That could be the problem why openvpn wont load..I receive this error on my CentOS panel when im trying to connect into the centos openvpn (with my winxp pc):
i've set up an openvpn server (with dhcp running on it) and i have to create compatible clients.the problem is how to get an ip by dhcp.with ubuntu i made a script like this
/sbin/ifconfig tap0 up /sbin/dhclient -e tap0
and everything works fine:tap0 goes up and then start a dhcp request to the server on tap0with fedora there is a nice problem i've noticed that is impossible to run dhclient later on a new interface because i receive this error "dhclient is already running".the tap0 goes up normally but i receive this error when i attempt to get an ip.is there a simple way to get an ip?if i try to kill or restart dhclient when the vpn tunnel is up,all'interfaces lost theirs ip and network goes down crashing my vpn...
how to let iptables to allow dns & dhcp distributions from the server to the clients only w/out exposing the port dhcp port udp 67,68 and tcp port 67,68 as well from the outside world.DHCP only uses udp, but still I also allowed tcp ports as well just to be sure & also I already allow DNS ports in the firewall w/c is not inluded below. linux newbie here,
when i issued the command below to allow those ports only to the internal network the firewall still blocking it. what seems to be the problem?? #iptables -A INPUT -m iprange --src-range 192.168.0.1-192.168.0.254 -p udp --dport 67 -j ACCEPT
I have got DHCP issues with Network Manager. Whenever I try to connect using static IP it works, but when I use use Netowork Manager with DHCP, it seems to try to connect and soon says "Network Disconnected"..I've managed to connect to wlan and eth using network, so there shouldn't be any hardware/driver issue.
