Networking :: Dhcp Offer Get Through Iptables Configuration?
Jun 5, 2011
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 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
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 a question regarding iptables.i have a server running ubuntu server 10.04 with 2 nic's, i want to use it to filter the internet trafic of the people in my network ussing dansguardian and squid. they both work fine.the only problem is how to get iptables to deal with this the right way.
I am trying to set up a DMZ host - that is, one multifunctional PC between the WAN and the LAN. I've started with a basic router, and expanding upon that as the need arises. I am currently trying to gain access (from the WAN) to a website hosted on one of the servers in the LAN, but I am having trouble accessing the host from the WAN; I think my iptables configuration may be too restrictive. On the DMZ host, I'm using Debian (Etch). I have setup dhcp3-server, a script to configure iptables and pound (reverse-proxy). The (virtual) machine has 4 network cards: eth0, eth1, eth2, eth3; eth0 is the WAN, eth1 through eth3 serve 3 different virtual LANs.
All machines in the LAN (except one windows 2008 server - I might want to address that problem later) get their IP adresses correctly via dhcp from the DMZ host. All machines on the LAN can access the internet (including the 2008 server if I configure it manually) as they should. If I access http://localhost on the DMZ host, pound reports "The service is not available. Please try again later." - as it should.
I can ping the DMZ host from the WAN on 10.0.0.79 However, if I try to access the DMZ host from the WAN (http://10.0.0.79) I get "Unable to connect" from firefox. I'm sure this is not a pound problem, so I think it's in the iptables, or maybe I should be installing some extra software that I'm unaware of.
I'm having a bizarre problem where my network connection stops working randomly. At first I thought it was a DNS issue since Firefox simply chilled out on "Looking up [hostname]" until it timed out, but after further investigation (pinging IP's, "host" and "dig" being unable to reach servers) it became apparent that I couldn't even access the DNS servers i.e. the Wicked Connection of the East was most sincerely dead.
There are two strange things about this: one, there are no errors except "timeout". The network manager is happy, Firefox is happy until the lookup fails... Two, the failures only start *after* DHCP configuration. DHCP configuration never has any trouble sending or receiving packets. I'm going to try static IP and whatnot to see if that helps, more information later.
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?
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
With Red Hat Linux as a DHCP server I want to connect windows xp so it may get ip address from the linux server on my test lab.Both of these computers are connected with a cross cable.
I assign ip assress to my eth0 192.168.1.10 with subnetmask 255.255.255.0
For the client i want that it may get Ip range from 192.168.1.50 to 192.168.1.55
Guide the minimum DHCP configuration so my client machine should get IP address from Linux server.
I need to shear internet i use isc-dhcp-serve and it work but internet doesn't work i have triad so many commends but still networking ... My setting is eth0 - wan eth1 -local
When I stop/start vm(not restart), dhclient becomes up and ip is assigned by dhcp. Why? -------------------------------- yoshi@vbox:~$ uname -a Linux vbox 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt11-1 (2015-05-24) x86_64 GNU/Linux -------------------------------- yoshi@vbox:~$ cat /etc/network/interfaces # This file describes the network interfaces available on your system # and how to activate them. For more information, see interfaces(5).
I'm trying to setup a DHCP server that serves several different VLANs, we have 5 in total. Our network is working correctly, with static IPs, we're able to ping across without any issues.
When I connect my debian box to an interface on VLAN5, statically assign an address in the correct range, it works. Similarly with all other VLANs.
To configure this box as a DHCP, I set one of the ports on the switch as trunk, connect that to the debian box to allow all VLAN traffic to reach my debian box.
I setup DHCP following the steps on [URL] ....
Then I configured different VLANs by following the steps on [URL] .....
However, with the vlans setup, I am unable to ping anything. This is essentially what I did.
Code: Select allSet the port on the switch to trunk with 802.1 encapsulation disable eth0 vconfig add eth0 5 # to add vlan 5 ifconfig eth0.5 192.168.5.254 netmask 255.255.255.0 up vconfig add eth0 5 # to add vlan 10 ifconfig eth0.5 192.168.10.254 netmask 255.255.255.0 up
[Code] ....
I do not know why I am unable to get any connectivity through my VLAN interfaces.
using Debian 5.0, GNOME desktop.my DSL service was to be connected today.the problem is my DSL light keeps blinking.ethernet light is solid.how do i setup my DHCP on my computer
I am connected to a network using any interface (eth0, eth1, or wlan0) that if my ip address was given out (dhcp) that my desktop responsiveness gets worse. Specifically the mouse has a sort of "sticky" feeling. I mean by that that I'm moving the physical mouse and the cursor is getting stuck here or there on the screen. It is extremely annoying. Here is my config file:
beethoven:~$ cat /etc/dhcp3/dhclient.conf # Configuration file for /sbin/dhclient, which is included in Debian's #dhcp3-client package. # # This is a sample configuration file for dhclient. See dhclient.conf's
I have setup a few machines within my house. The Debian Squeeze machines do not provide a host name in the DHCP client list on my router. Strangely, my Ubuntu, Android, and Blackberry machines do show host names. I have noticed the same behavior when wirelessly tethering my Debian laptop to my Android phone (which also uses DHCP). Is there something I need to enable to have the name show up on the router?
Setup a DNS/DHCP/Directory server on Debian? I would like to configure the things in Debian so that can join Linux and Windows(if possible as m not sure yet) clients to the directory server. Any links to setup both Forward and Reverse lookup zone in the environment.
I'm new to the forum and actually to Debian as well. Have been running Ubuntu for the past few years. Just setup a small Dell laptop to use as a Squeezebox and Print server. It's been up 6 days without a hitch as far as serving music to the squeezebox and printing. The problem is that it loses it's static IP, so as long as I look it up and change the radio Squeezebox and printer definitions around on the clients everything keeps working.
Does anyone have any ideas?If the connection drops for some reason and the system has to re-initialize the connection, shouldn't it use the /etc/network/interfaces file and get back to the static IP that it is configured for?If anyone has any ideas of why this could be happening or have a solution, I would really appreciate the help.
I just put a pfSense firewall inbetween my ADSL router and my LAN. It's configured to have a cachng DNS server and a DHCP server. Among other things. For reasons beyond this post the address range served by DHCP changed from 10.0.0.x to 192.168.1.x. The new DHCP server gives 192.168.1.1 as gateway and DNS server name and not the public IP addresses of our internet provider.
After reconnecting our client machines everything worked just fine on the win-xp boxes, but the Debian Squeeze servers and Ubuntu 10.4 clients all started to get network timeouts. If I ping public websites it works but browsing to the same servers fails. Other services like POP3 and IMAP also fails. All machines use WiFi to connect and the access point is the same as before.
What could it be that make the debian boxes fail? My laptop runs squeeze too and also fails. But when connecting to various other access points at hotels and such I do not get this problem.
Another weird thing is that the debian server running virtualbox cannot do things online but the virtual windows boxes running on this machine can. Weird! Where should I start looking? How is networking/dhcp clients on Debian different from Windows XP?
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.
I am trying to enable DHCP so that it will give out IP's to some XP boxes when they boot. I have had success doing it dynamically, but not statically using the host declaration. host xpTest { hardware ethernet 00:50:56:2A:3B:00; fixed-address 192.168.100.2; } My question is, what should the subnet declaration be if I only want to hand out static IP's like this? Also, the host is the same name that is specified in /etc/hosts correct?
Automatic Proxy Configuration via DHCP | AGIX Linux Tutorials & HowTo's | Ubuntu Focuson openSUSE not work, Why? # These 2 following lines are the key to your pac success:option local-pac-server code 252 = text;option local-pac-server "http://192.168.1.254/wpad.pac";
I follow this instructions but after iptables-restore < /etc/iptables.test.rules I see this error # iptables-restore < /etc/iptables.test.rules Bad argument `#' Error occurred at line: 3 Try `iptables-restore -h' or 'iptables-restore --help' for more information. The line 3 is the same as the link - # Allows all loopback (lo0) traffic and drop all traffic to 127/8 that doesn't use lo0
