Dear All,
I have a ADSL broadband connection of BSNL. The ADSL modem is connected to our Internet Server (Fedora box) to one of the NIC card(eth1), the other NIC card (eth0) is connected to our LAN switch. This Fedora box acts as the gateway machine to the Internet for our LAN.
The Problem: ------------ The LAN users were not getting the Internet. I saw the PPP link was up and running on the Server and also the Modem link was ok., but I couldn't ping to their (ISP's) end. (Destination port unreachable message was coming).
I called the ISP and after a while, the LAN users were able to get the Internet but during the same time, I was not able to ping to their gateway and also to their DNS IP from my Internet Server.
Then when i restarted my iptables script file, i was able to ping ISP's gateway and their DNS IP too.
I just want to know, when my LAN users were getting the Internet, Why I couldn't get the reply from either their (ISP's) gateway / their DNS IP.
Hope someone might be able to explain me what the problem could be.
Thanks in Advance,
Regards, George
On Wed, Apr 8, 2009 at 1:05 PM, george@annamsoft.com wrote:
Hope someone might be able to explain me what the problem could be.
Providing more information on the setup and what you have done will be very useful. You could start with the output of these commands ifconfig eth0 ifconfig eth1 cat /proc/sys/net/ipv4/ip_forward
Dear All,
The ISP guys called up and said some port was changed at their end and hence the problem, but i would like to know once there was no gateway route/path on the Internet Server, how come the LAN users were able to browse from their workstation after the port was changed at the BSNL end before me running the firewall Script which starts the adsl connection and assigns IP to the ppp0 interface, this boggles my mind.
During that time when this problem occurred, following was observed on the Internet Server:
ifconfig eth1 had its IP set OK (i.e our internal LAN IP)
ifconfig ppp0 had NO IP assigned (Public IP-Dynamic) since as BSNL said they were changing some port at their end.
IP forwarding was OK.
Regards, George John
On Wed, Apr 8, 2009 at 1:05 PM, george@annamsoft.com wrote:
Hope someone might be able to explain me what the problem could be.
Providing more information on the setup and what you have done will be very useful. You could start with the output of these commands ifconfig eth0 ifconfig eth1 cat /proc/sys/net/ipv4/ip_forward
--
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george@annamsoft.com wrote:
The ISP guys called up and said some port was changed at their end and hence the problem, but i would like to know once there was no gateway route/path on the Internet Server, how come the LAN users were able to browse from their workstation after the port was changed at the BSNL end before me running the firewall Script which starts the adsl connection and assigns IP to the ppp0 interface, this boggles my mind.
During that time when this problem occurred, following was observed on the Internet Server:
ifconfig eth1 had its IP set OK (i.e our internal LAN IP)
ifconfig ppp0 had NO IP assigned (Public IP-Dynamic) since as BSNL said they were changing some port at their end.
IP forwarding was OK.
Since there is no black magic involved ;-) , it is most likely that a route was available which went un-noticed. Sometimes with cable internet which uses no dhcp and only pppoe, it so happens that dhcp does work sometimes and even allows browsing without pppoe. I have noticed this with new installations or after replacement of ethernet cards. However after the new mac id is locked at the cablenet provider end, there is no dhcp and net access is only through pppoe. Those familiar with setup of pppoe Servers may be able to shed more light on this phenomenon.
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george＠annamsoft.com -
Mehul Ved -
Rony