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-   -   RPC error with pppd+pppol2tp (https://www.linuxquestions.org/questions/linux-networking-3/rpc-error-with-pppd-pppol2tp-669918/)

monohouse 09-14-2008 05:07 PM
websites do not load with pptp
 
I have compiled and installed pppol2tp and the plugin appears to be working in pppd, but the test doesn't pass (according to installation instructions):

Code:
$/usr/sbin/pppd debug nodetach noauth plugin pppol2tp.so pppol2tp 42

  Plugin pppol2tp.so loaded.
  Given FD for PPPoL2TP socket invalid (Bad file descriptor)
which is according to installation instruction fine.

Code:
$/usr/bin/l2tpconfig
localhost: RPC: Port mapper failure - RPC: Unable to receive
Code:
$ rpcinfo -p
rpcinfo: can't contact portmapper: RPC: Remote system error - Connection refused
/etc/services
Code:
l2f                1701/tcp        l2tp
l2f                1701/udp        l2tp

WildPossum 09-14-2008 10:59 PM
The first error message indicates that the "fd" (File Descriptor) you have given is incorrect/or in-use.

In case you unaware what a fd is, its simply a index number into the file structure (or I/O under Linux) that points to the device or file your program is doing to or intent to work with. The error message your got come whenever the program opens the device, and the returning result says - nope, can't use and prints the error message your got. The other messages following are because the first fd is not available so it keeps on trying to do what your asked.

To help you understand further, the keyboard is fd=0, output (normal) is fd=1, output (errors) is fd=2, hence that is why you sometimes see things like "2&1" which means the output of both fd 1 & fd 2 go to ... etc.

Check the program itself by issuing a --help as in:
"/usr/sbin/pppd --help" and check for which fd's are valid options. If your sure your using the correct fd (I suspect its the 42 at the end of the CLI), then maybe there is another process/program already using it so have a look at who if anyone is using it.

The tool you use is "lsof" which stands for "list-open-files", you will see that the lsof header is "COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME" so looking down the column "FD" you can tell what program/process is using whih fd.

A quick list is to combine commands on the CLI (the essance of UNIX) as in "lsof | grep 42", which will now list any fd with the digits 42 in the fd field.

Once your got the fd sorted out, I think you will be fine.
Hope this helps.

monohouse 09-15-2008 10:58 AM
websites do not load with pptp
 
thanks, I managed to start l2tpconfig eventually, but that did not solve the problem: connecting to the ISP via l2tp.

so instead I am now trying to use pptp, and while now I have more progress, I am not successful:

from /var/log/errors.log
Code:
pppd[1090]: not replacing existing default route via 172.26.96.1
the connection to the tunnel does get established, but there is no ping
I have tried to
Code:
route del default
both before and after connecting, but the connection is killed after I do that, I have commented the lines "gateway=" and "ROUTES=(gateway)" but that still did not prevent the dhcp from creating default gateway

I have also tried to create a "static route" according to some instructions at http://www.technion.ac.il/~eyalroz/l...ptp.html#intro
Quote:
Static routes on the cables network segment
Our first task is to make sure that, no matter what happens, the IP packets you're sending to your ISP's PPTP server (and to your cables DHCP server) never get sent by mistake over the PPP interface instead of over its underlying ethernet interface. To ensure this we will set specific routing table entries for these two servers whenever the ethernet interface to the cables LAN network comes up. In Debian 3.0/3.1, edit your /etc/network/interfaces file. The cables ethernet interface (e.g. eth0) should have a block beginning with the lines

iface cables ethernet interface inet dhcp

possibly followed by lines with interface-specific options. To this block of options add the line

up ip route replace your ISP's PPTP server IP dev cables ethernet interface
up ip route replace cables DHCP server IP dev cables ethernet interface

With other distributions use whatever scripting mechanism is available to run the following two commands after the cables ethernet interface is up, and before starting the VPN connection to your ISP:

ip route replace your ISP's PPTP server IP dev cables ethernet interface
ip route replace cables DHCP server IP dev cables ethernet interface

The PPTP server IP is the one you located in the table above for your ISP; the cables' DHCP however, is a little trickier. Here's a script called dhcp-server-of-if, which takes as an argument the name of an ethernet interface configured by DHCP (e.g. eth0) and returns the address of the DHCP server:
but I do not have the commands "up" and "iface" so I just used the "route" ones.
and while those commands did help prevent the pptp connection from closing after removing the default route, when I replaced the default route with the address of the gateway provided by the pptp connection, it did not work

Code:
Sep 15 22:37:03 myhost pptp[1094]: anon log[ctrlp_disp:pptp_ctrl.c:896]: Outgoing call established (call ID 3, peer's call ID 60015).
this is the output of "route" before connection:
Code:
Kernel IP routing table
Destination    Gateway        Genmask        Flags Metric Ref    Use Iface
192.168.101.102 *              255.255.255.255 UH    0      0        0 eth1
212.179.61.76  *              255.255.255.255 UH    0      0        0 eth1
192.168.101.101 *              255.255.255.255 UH    0      0        0 eth1
172.26.96.0    *              255.255.224.0  U    0      0        0 eth1
169.254.0.0    *              255.255.0.0    U    0      0        0 eth1
default        172.26.96.1    0.0.0.0        UG    0      0        0 eth1
212.179.61.76 is the address of the PPTP server to which it is connecting
192.168.101.101\102 is the address of the DNS server of the cable connection
and i have no idea what 169.254.0.0 is doing there
172.26.96.1 is the gateway of the cable interface

this is the /var/lib/dhcpcd/dhcpcd-eth1.info before connection:
Code:
IPADDR='172.26.125.100'
NETMASK='255.255.224.0'
NETWORK='172.26.96.0'
BROADCAST='255.255.255.255'
MTU='576'
ROUTES=''
GATEWAYS='172.26.96.1'
HOSTNAME='myhost'
DNSSERVERS='192.168.101.101 192.168.101.102'
DHCPSID='213.57.35.2'
LEASEDFROM='1221545738'
LEASETIME='552635'
RENEWALTIME='276317'
REBINDTIME='483555'
INTERFACE='eth1'
CLASSID='dhcpcd 3.2.1'
CLIENTID='01:00:50:fc:6c:0d:e0'
DHCPCHADDR='00:50:fc:6c:0d:e0'
this is the /etc/ppp/peers/interal file (the user field was omitted but is present and correct):
Code:
linkname interal
pty "pptp 212.179.61.76 --nolaunchpppd"
nobsdcomp
nodeflate
noauth
usepeerdns
defaultroute
#replacedefaultroute # this doesn't work
remotename 212.179.61.76
file /etc/ppp/options.pptp
ipparam interal
this is the /etc/ppp/options.pptp file:
Code:
lock
noauth
name {as specified in the /etc/ppp/peers/interal file}
refuse-eap
refuse-chap
refuse-mschap
refuse-mschap-v2
nobsdcomp
nodeflate
this is the output of ifconfig eth1:
Code:
eth1      Link encap:Ethernet  HWaddr 00:50:FC:6C:0D:E0 
          inet addr:172.26.125.100  Bcast:255.255.255.255  Mask:255.255.224.0
          UP BROADCAST RUNNING MULTICAST  MTU:576  Metric:1
          RX packets:22556 errors:1 dropped:0 overruns:0 frame:0
          TX packets:799 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:4341169 (4.1 Mb)  TX bytes:145015 (141.6 Kb)
          Interrupt:7 Base address:0xc000
which indicates that the connection to the cable network is established.
and now I am attempting to connect:
Code:
pon interal debug dump logfd 2
to see if the connection was established:ifconfig
Code:
ppp0      Link encap:Point-to-Point Protocol 
          inet addr:217.22.120.167  P-t-P:217.22.120.1  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:10 errors:0 dropped:0 overruns:0 frame:0
          TX packets:4 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:3
          RX bytes:477 (477.0 b)  TX bytes:82 (82.0 b)
/var/log/errors.log line at time of connection:
Code:
Sep 15 23:28:02 myhost pppd[1379]: not replacing existing default route via 172.26.96.1
route:
Code:
Kernel IP routing table
Destination    Gateway        Genmask        Flags Metric Ref    Use Iface
217.22.120.1    *              255.255.255.255 UH    0      0        0 ppp0
192.168.101.102 *              255.255.255.255 UH    0      0        0 eth1
212.179.61.76  *              255.255.255.255 UH    0      0        0 eth1
192.168.101.101 *              255.255.255.255 UH    0      0        0 eth1
172.26.96.0    *              255.255.224.0  U    0      0        0 eth1
169.254.0.0    *              255.255.0.0    U    0      0        0 eth1
default        172.26.96.1    0.0.0.0        UG    0      0        0 eth1
then try to replace the default gateway with
Code:
ip route replace default via 217.22.120.196 dev ppp0
Code:
ip route replace default via 212.179.61.76 dev ppp0
Code:
ip route replace default via 217.22.120.1 dev ppp0
but none of them work. 2 of the options 217.22.120.1 and 217.22.120.196 manage to get a reply to a ping:
Code:
ping www.interal.co.il
PING www.interal.co.il (217.22.112.130) 56(84) bytes of data.
64 bytes from 217.22.112.130: icmp_seq=1 ttl=122 time=18.7 ms
64 bytes from 217.22.112.130: icmp_seq=2 ttl=122 time=20.0 ms
64 bytes from 217.22.112.130: icmp_seq=3 ttl=122 time=24.7 ms
64 bytes from 217.22.112.130: icmp_seq=4 ttl=122 time=20.1 ms
64 bytes from 217.22.112.130: icmp_seq=5 ttl=122 time=19.8 ms
but web sites do not load

lsmod:
Code:
Module                  Size  Used by
ppp_async              6016  0
crc_ccitt                992  1 ppp_async
ppp_generic            13300  1 ppp_async
slhc                    4832  1 ppp_generic
af_packet              11232  0
mousedev              11236  1
psmouse                14600  0
intel_agp              17660  1
agpgart                19440  1 intel_agp
8139too                13632  0
mii                    3104  1 8139too
bitrev                  800  1 8139too
crc32                  2944  1 8139too
according to http://pptpclient.sourceforge.net/ho...osis.phtml#gre
I need to run tcpdump, here are it's results:
Code:
tcpdump -i ppp0
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on ppp0, link-type LINUX_SLL (Linux cooked), capture size 96 bytes
00:41:25.508730 IP 84.99.205.140.55096 > 217.22.120.196.5783: UDP, length 35
00:41:28.721382 IP 81.62.29.112.12847 > 217.22.120.196.5783: UDP, length 35
00:41:29.819111 IP 88.191.71.93.17196 > 217.22.120.196.5783: UDP, length 35
00:41:43.754646 IP 82.159.105.110.49150 > 217.22.120.196.5783: UDP, length 35
00:41:46.111244 IP 85.250.5.249.10298 > 217.22.120.196.5783: UDP, length 22
00:41:47.069533 IP 82.159.105.110.49150 > 217.22.120.196.5783: UDP, length 35
00:41:49.624743 IP 81.37.115.168.62452 > 217.22.120.196.5783: UDP, length 35
00:42:12.913298 IP 81.44.71.254.4672 > 217.22.120.196.5783: UDP, length 35
00:42:16.142670 IP 85.232.180.29.11020 > 217.22.120.196.5783: UDP, length 22
00:42:16.363863 IP 83.44.2.127.4672 > 217.22.120.196.5783: UDP, length 35
00:42:17.290424 IP 189.13.155.159.61330 > 217.22.120.196.5783: UDP, length 35
00:42:33.276519 IP 59.121.46.28.4672 > 217.22.120.196.5783: UDP, length 35
00:42:54.781320 IP 89.139.49.63.41907 > 217.22.120.196.5783: UDP, length 28
00:43:00.075388 IP 222.66.57.82.55053 > 217.22.120.196.5783: UDP, length 38
00:43:06.030671 IP 201.28.204.197.49626 > 217.22.120.196.5783: UDP, length 22
00:43:20.239821 IP 87.68.51.71.10094 > 217.22.120.196.5783: UDP, length 35
00:43:21.479301 IP 190.31.45.43.25 > 217.22.120.196.5783: UDP, length 35
00:43:23.547307 IP 213.44.253.49.8128 > 217.22.120.196.5783: UDP, length 22
00:43:29.638843 IP 38.107.160.220.4662 > 217.22.120.196.5783: UDP, length 27
00:43:29.639486 IP 38.107.160.220.4662 > 217.22.120.196.5783: UDP, length 35
00:43:30.256697 IP 87.117.53.194.14673 > 217.22.120.196.5783: UDP, length 35
00:43:41.919367 IP 151.47.84.177.64965 > 217.22.120.196.5783: UDP, length 22
00:43:45.413855 IP 78.136.171.91.8617 > 217.22.120.196.5783: UDP, length 22
00:43:45.846963 IP 79.127.3.220.55074 > 217.22.120.196.5783: UDP, length 35
00:43:52.994972 IP 124.82.76.75.22130 > 217.22.120.196.5783: UDP, length 35
00:43:58.979550 IP 83.165.165.207.4672 > 217.22.120.196.5783: UDP, length 35
00:44:19.855645 IP 84.127.168.3.4672 > 217.22.120.196.5783: UDP, length 35
00:45:06.457013 IP 201.27.167.195.4672 > 217.22.120.196.5783: UDP, length 22
00:45:13.922626 IP 77.127.83.16.4672 > 217.22.120.196.5783: UDP, length 35
00:45:29.398573 IP 85.85.3.120.61838 > 217.22.120.196.5783: UDP, length 35
00:45:40.482154 IP 87.17.167.194.4672 > 217.22.120.196.5783: UDP, length 35
00:45:54.357894 IP 82.242.255.164.10669 > 217.22.120.196.5783: UDP, length 22
00:45:54.759288 IP 83.147.87.121.4672 > 217.22.120.196.5783: UDP, length 35
00:45:58.087926 IP 88.25.195.163.11321 > 217.22.120.196.5783: UDP, length 35
00:45:58.470271 IP 118.166.130.145.7322 > 217.22.120.196.5783: UDP, length 35
00:46:04.693088 IP 201.92.36.23.44672 > 217.22.120.196.5783: UDP, length 35
00:46:07.780064 IP 79.181.142.187.46248 > 217.22.120.196.5783: UDP, length 35
^C
37 packets captured
37 packets received by filter
0 packets dropped by kernel
there are no GRE packets or packets on port 1723:
Code:
tcpdump -i ppp0 
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on ppp0, link-type LINUX_SLL (Linux cooked), capture size 96 bytes
02:29:43.844499 IP 217.22.120.61.37654 > 213.57.1.13.www: S 3835668788:3835668788(0) win 5840 <mss 1460,sackOK,timestamp 104231 0,nop,wscale 5>
02:29:46.583609 IP 89.141.79.219.50961 > 217.22.120.61.4672: UDP, length 22
02:29:46.583705 IP 217.22.120.61 > 89.141.79.219: ICMP 217.22.120.61 udp port 4672 unreachable, length 58
02:29:46.841585 IP 217.22.120.61.37654 > 213.57.1.13.www: S 3835668788:3835668788(0) win 5840 <mss 1460,sackOK,timestamp 104531 0,nop,wscale 5>
02:29:47.472157 IP 87.11.246.208.29394 > 217.22.120.61.27308: UDP, length 51
02:29:47.472250 IP 217.22.120.61 > 87.11.246.208: ICMP 217.22.120.61 udp port 27308 unreachable, length 87
02:29:48.764322 IP 87.231.122.117.63055 > 217.22.120.61.27308: UDP, length 35
02:29:48.764415 IP 217.22.120.61 > 87.231.122.117: ICMP 217.22.120.61 udp port 27308 unreachable, length 71
any ideas ?


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