I am not very new to linux and I have used it for one year and every thing went ok until my university network changed from LAN to VPN-based about 2 weeks ago.I have googled and forum-searched(including this forum) during these 2 weeks and I have done following things.Finally I could connect to my vpn server(it accepts me and charges my connection time!) but no data exchanges established and firefox could not find pages.Please help me ,I am starting to be disappointed with linux .I can tolerate other problems of linux but not no-internet-connection.

I have done:
1-First I googled and found pptpclient at sourceforge.net and did what it said for my Fedora Core 3.

2-Next I changed my OS from Fedora core 3 to SuSE10, after several unsuccessful attemps to install pptpclient ( I didnt have any other internet connection to use yum).

3-Every thing worked fine with SuSE10 : configuring DNS connection with P-t-P tunelling with these information from my Windows machine:
- DNS server and DHCP server and VPN server :192.168.1.1(which is equal to vpn.kooy.tums.ac.ir)

- Subnet Mask: 255.255.255.0
- No need to use "require-mppe"
- I disabled my firewall
- Idle delay set to 0

I could connect to vpn server but no web page was accesible and no data-exchange established.Here is Kinternet log:
SuSE Meta pppd (smpppd-ifcfg), Version 1.59 on linux.
Status is: disconnected
trying to connect to smpppd
connect to smpppd
Status is: disconnected
Status is: connecting
pppd[0]: Plugin passwordfd.so loaded.
pppd[0]: Renamed interface ppp0 to dsl0
pppd[0]: Using interface dsl0
Status is: connecting
pppd[0]: Connect: dsl0 <--> /dev/pts/1
pppd[0]: CHAP authentication succeeded: ^JAuthentication Successful.^J
pppd[0]: replacing old default route to eth0 [192.168.1.1]
pppd[0]: local IP address 192.168.2.18
pppd[0]: remote IP address 192.168.2.5
pppd[0]: primary DNS address 192.9.9.3
pppd[0]: Script /etc/ppp/ip-up finished (pid 7282), status = 0x0
Status is: connected

4-ifconfig(when I am connected) :
"# ifconfig ppp0 | grep inet " it replies that no ppp0 found and
when I write
"# ifconfig dsl0 | grep inet " it says that:
inet addr 192.168.2.5 p-t-p 192.168.2.5 Mask 255.255.255.255

linux:~ # ifconfig
eth0 Link encap:Ethernet HWaddr 00:20:ED:4D:EC:FD
inet addr:192.168.1.10 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::220:edff:fe4d:ecfd/64 Scope:Link
UP BROADCAST NOTRAILERS RUNNING MULTICAST MTU:1500 Metric:1
RX packets:6991 errors:0 dropped:0 overruns:0 frame:0
TX packets:174 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:439341 (429.0 Kb) TX bytes:14927 (14.5 Kb)

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:122 errors:0 dropped:0 overruns:0 frame:0
TX packets:122 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:8059 (7.8 Kb) TX bytes:8059 (7.8 Kb)

5-when I ping 192.168.1.1 (whether connected or not) it is OK(no missed pocket).

6-lspci:
linux:~ # lspci
00:00.0 Host bridge: Intel Corporation 82845G/GL[Brookdale-G]/GE/PE DRAM Controller/Host-Hub Interface (rev 02)
00:01.0 PCI bridge: Intel Corporation 82845G/GL[Brookdale-G]/GE/PE Host-to-AGP Bridge (rev 02)
00:1d.0 USB Controller: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #1 (rev 02)
00:1d.1 USB Controller: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #2 (rev 02)
00:1d.2 USB Controller: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #3 (rev 02)
00:1d.7 USB Controller: Intel Corporation 82801DB/DBM (ICH4/ICH4-M) USB2 EHCI Controller (rev 02)
00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev 82)
00:1f.0 ISA bridge: Intel Corporation 82801DB/DBL (ICH4/ICH4-L) LPC Interface Bridge (rev 02)
00:1f.1 IDE interface: Intel Corporation 82801DB (ICH4) IDE Controller (rev 02)
00:1f.3 SMBus: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) SMBus Controller (rev 02)
00:1f.5 Multimedia audio controller: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) AC'97 Audio Controller (rev 02)
01:00.0 VGA compatible controller: nVidia Corporation NV18 [GeForce4 MX 4000 AGP 8x] (rev c1)
02:07.0 USB Controller: NEC Corporation USB (rev 41)
02:07.1 USB Controller: NEC Corporation USB (rev 41)
02:07.2 USB Controller: NEC Corporation USB 2.0 (rev 02)
02:08.0 Ethernet controller: Intel Corporation 82801DB PRO/100 VE (CNR) Ethernet Controller (rev 82)

7- resolve.conf:
### BEGIN INFO
#
# Modified_by: dhcpcd
# Backup: /etc/resolv.conf.saved.by.dhcpcd.eth0
# Process: dhcpcd
# Process_id: 7047
# Script: /sbin/modify_resolvconf
# Saveto:
# Info: This is a temporary resolv.conf created by service dhcpcd.
# The previous file has been saved and will be restored later.
#
# If you don't like your resolv.conf to be changed, you
# can set MODIFY_{RESOLV,NAMED}_CONF_DYNAMICALLY=no. This
# variables are placed in /etc/sysconfig/network/config.
#
# You can also configure service dhcpcd not to modify it.
#
# If you don't like dhcpcd to change your nameserver
# settings
# then either set DHCLIENT_MODIFY_RESOLV_CONF=no
# in /etc/sysconfig/network/dhcp, or
# set MODIFY_RESOLV_CONF_DYNAMICALLY=no in
# /etc/sysconfig/network/config or (manually) use dhcpcd
# with -R. If you only want to keep your searchlist, set
# DHCLIENT_KEEP_SEARCHLIST=yes in /etc/sysconfig/network/dhcp or
# (manually) use the -K option.
#
### END INFO
nameserver 192.168.1.1


8- dmesg was very long but if it helps I can paste it.

9- I tried to change the Default gateway to 192.168.1.1 but nothing achieved.

10-Can anyone help me?where is the problem?

No comments?
please help

Try turning off your firewall. There are certain combinations of firewall vpn and local lan access that mean no external internet. My problem was the same. I managed to find a table on my uni's website which led me to the conclusion that the firewall was the problem despite the relevant ports having been opened and the vpn client claiming success. When I shut down the firewall it worked fine. Not that much of a problem for me thanks to my router but it could be for you.

Thanks fraz for your notice.
I have disabled firewall in YaST2 but no improvement.Somewhere I read maybe the firewall continue running even disabling firewall with YaST2,but I dont know what else I should do.

Any help is appreciated .