[oclug]networking: sending from inside network to isp
Martin Hicks
mort at bork.org
Mon Oct 21 21:57:04 EDT 2002
You must do IP-Masquerading, because your internal net is non-routable
(network is within 192.168.0.0/16).
http://www.tldp.org/HOWTO/IP-Masquerade-HOWTO/index.html
mh
On Mon, Oct 21, 2002 at 08:46:03PM -0400, Brenda J. Butler wrote:
>
>
> I have two machines at home. I used to use the machine
> which is connected to the modem to dial up and as my
> main machine, but now I want to use it as a firewall
> and use the other machine as my main machine.
>
> My problem is that the second machine (taz) can ping
> the firewall machine (seal). However, some attempts
> to communicate with machines outside my home network
> result in silence and timeouts (even when the modem
> has connected ! heh heh)
>
> seal is running debian woody 3.0, kernel 2.2.19
> ipchains -L returns:
> Chain input (policy ACCEPT):
> Chain forward (policy ACCEPT):
> Chain output (policy ACCEPT):
>
> taz is running debian woody 3.0, kernel 2.4.18
> iptables -L returns:
> iptables v1.2.6a: can't initialize iptables table `filter': iptables who? (do you need to insmod?)
> Perhaps iptables or your kernel needs to be upgraded.
>
> When I modprobe ip_tables and iptable_filter and ip_conntrack and
> then run iptables -L I get:
> tazmaniandevil:/usr/share/doc/HOWTO/en-txt# iptables -L
> Chain INPUT (policy ACCEPT)
> target prot opt source destination
>
> Chain FORWARD (policy ACCEPT)
> target prot opt source destination
>
> Chain OUTPUT (policy ACCEPT)
> target prot opt source destination
> tazmaniandevil:/usr/share/doc/HOWTO/en-txt#
>
>
> Examples of things I've tried:
>
> ping from taz to seal: works
> The modem lights don't blink.
> The internal network hub light blinks.
>
> ping from seal to taz: works
> The modem lights don't blink.
> The internal network hub light blinks.
>
> ping from seal to isp's ip ("remote" ip in ppp connection log): works
> The modem send and receive lights blink.
> The internal network hub light also blinks.
>
> ping from seal to isp's ip ("local" ip in ppp connection log): works
> The modem send and receive lights don't blink.
> The internal network hub light does blink.
>
> ping from seal to isp's nameserver (specified as dotted quad): fails.
> I see the modem lights light up for send, but not for receive.
> The internal network hub light does not blink.
>
> ping from seal to another outside nameserver (same failure)
>
> ping from taz to isp's nameserver (specified as dotted quad): fails.
> I don't see the modem lights light up at all. The hub
> light blinks (between taz and seal).
>
> fetchmail downloads and exim mail uploads work (to/from seal).
>
> visiting an external web page from seal works.
>
> visiting an external web page from taz doesn't (times out)
>
>
> bjb at tazmaniandevil ~ 510 $ /sbin/route
> Kernel IP routing table
> Destination Gateway Genmask Flags Metric Ref Use Iface
> localnet * 255.255.255.0 U 0 0 0 eth0
> default seal.stuffed.an 0.0.0.0 UG 0 0 0 eth0
> bjb at tazmaniandevil ~ 511 $ ifconfig
> bash: ifconfig: command not found
> bjb at tazmaniandevil ~ 512 $ /sbin/ifconfig
> eth0 Link encap:Ethernet HWaddr 08:00:20:7C:9C:FD
> inet addr:192.168.110.44 Bcast:192.168.110.255 Mask:255.255.255.0
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> RX packets:2961627 errors:0 dropped:0 overruns:0 frame:0
> TX packets:1565185 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:100
> RX bytes:4313278147 (4.0 GiB) TX bytes:106629622 (101.6 MiB)
> Interrupt:32
>
> lo Link encap:Local Loopback
> inet addr:127.0.0.1 Mask:255.0.0.0
> UP LOOPBACK RUNNING MTU:16436 Metric:1
> RX packets:427 errors:0 dropped:0 overruns:0 frame:0
> TX packets:427 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:0
> RX bytes:38646 (37.7 KiB) TX bytes:38646 (37.7 KiB)
>
> bjb at tazmaniandevil ~ 513 $
>
>
> bjb at seal:~$ /sbin/route
> Kernel IP routing table
> Destination Gateway Genmask Flags Metric Ref Use Iface
> tnt04.magma.ca * 255.255.255.255 UH 0 0 0 ppp0
> localnet * 255.255.255.0 U 0 0 0 eth0
> default * 0.0.0.0 U 0 0 0 ppp0
> bjb at seal:~$ /sbin/ifconfig
> eth0 Link encap:Ethernet HWaddr 08:00:20:76:0C:60
> inet addr:192.168.110.5 Bcast:192.168.110.255 Mask:255.255.255.0
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> RX packets:2255380 errors:0 dropped:0 overruns:0 frame:0
> TX packets:4283525 errors:1 dropped:0 overruns:0 carrier:1
> collisions:6 txqueuelen:100
> RX bytes:153527361 (146.4 MiB) TX bytes:1931003524 (1.7 GiB)
> Interrupt:38 Base address:0xf600
>
> lo Link encap:Local Loopback
> inet addr:127.0.0.1 Mask:255.0.0.0
> UP LOOPBACK RUNNING MTU:3924 Metric:1
> RX packets:36122 errors:0 dropped:0 overruns:0 frame:0
> TX packets:36122 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:0
> RX bytes:10272940 (9.7 MiB) TX bytes:10272940 (9.7 MiB)
>
> ppp0 Link encap:Point-to-Point Protocol
> inet addr:64.26.139.172 P-t-P:206.191.0.146 Mask:255.255.255.255
> UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1524 Metric:1
> RX packets:46 errors:0 dropped:0 overruns:0 frame:0
> TX packets:107 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:10
> RX bytes:1758 (1.7 KiB) TX bytes:5864 (5.7 KiB)
>
> bjb at seal:~$
>
>
>
> I see nothing related to refused, rejected or dropped network
> connections or packets in my log files.
>
> Although... there is something about "Cannot determine ethernet
> address for proxy ARP" every time I connect via ppp.
>
>
> So! What do I look for next? As I'm a beginner at networking,
> please don't hesitate to ask me if "the cable is plugged in".
> It probably isn't. Also if the answer is obvious to you from
> the above data, please explain it to me 'cause its not obvious
> to me.
>
> Thanks in advance!
>
> --
> bjb at achilles dot net
> Debian http://www.debian.org
>
> _______________________________________________
> oclug mailing list
> oclug at lists.oclug.on.ca
> http://www.oclug.on.ca/mailman/listinfo/oclug
--
Martin Hicks || mort at bork.org || PGP/GnuPG: 0x4C7F2BEE
plato up 20 days, 3:54, 13 users, load average: 0.02, 0.04, 0.06
Beer: So much more than just a breakfast drink.
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