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I'm trying to set up masq on a machine running Red Hat 7.1, with kernel
upgraded to 2.4.6. I followed the instructions in the HOWTO, and in the
testing section, I get as far as pinging from my Windows machine (being
masq'ed) to the external interface to the Linux box (running RP-PPPoE on an
ADSL connection) without difficulty. But when I try to ping microsoft.com from
the Windows machine, I don't get a response, *but* the little lights blink on
the network hub and the DSL modem. After running around trying several
different things (checking interfaces, confirming iptables setup, etc.), I
finally got tcpdump running on the Linux box and listened while I tried to
ping microsoft.com (which I can ping fine from the Linux box) from the Windows
machine. Here's the result (note that I told it not to dump port 23 since I'm
telnetting in from the Windows machine; also, eth0 is the local network, and
eth1 goes to the Internet):

[root@woodenspoon init.d]# tcpdump not port 23
Kernel filter, protocol ALL, TURBO mode (575 frames), datagram packet socket
tcpdump: listening on all devices
17:09:31.637472 eth1 > PPPoE  [ses 0x2103] LCP EchoReq id=0x7a
magic=0x1e6caa6
17:09:31.648464 eth1 < PPPoE  [ses 0x2103] LCP EchoRep id=0x7a
magic=0xa19d308
17:09:32.408196 eth0 < 10.0.0.2.1048 > 207.29.188.186.domain: 1+ A?
www.microsoft.com. (35)
17:09:32.408711 ppp0 > user-2iniahq.dialup.mindspring.com.1048 >
207.29.188.186.domain: 1+ A? www.microsoft.com. (35)
17:09:32.409268 eth1 > PPPoE  [ses 0x2103]
user-2iniahq.dialup.mindspring.com.1048 > 207.29.188.186.domain: 1+ A?
www.microsoft.com. (35)
17:09:32.420856 ppp0 > user-2iniahq.dialup.mindspring.com.1024 >
ns2.mindspring.com.domain: 11263+ PTR? 186.188.29.207.in-addr.arpa. (45) (DF)
17:09:32.421426 eth1 > PPPoE  [ses 0x2103]
user-2iniahq.dialup.mindspring.com.1024 > ns2.mindspring.com.domain: 11263+
PTR? 186.188.29.207.in-addr.arpa. (45) (DF)
17:09:32.817631 eth1 < PPPoE  [ses 0x2103] jfk3-core1-h4-1-0.4.atlas.digex.net
> user-2iniahq.dialup.mindspring.com: icmp: time exceeded in-transit [tos
0xc0]
17:09:32.818122 ppp0 < jfk3-core1-h4-1-0.4.atlas.digex.net >
user-2iniahq.dialup.mindspring.com: icmp: time exceeded in-transit [tos 0xc0]
17:09:32.818421 eth0 > jfk3-core1-h4-1-0.4.atlas.digex.net > 10.0.0.2: icmp:
time exceeded in-transit [tos 0xc0]
17:09:34.034977 eth0 < 10.0.0.2.1048 > 207.29.188.186.domain: 1+ A?
www.microsoft.com. (35)
17:09:34.035214 ppp0 > user-2iniahq.dialup.mindspring.com.1048 >
207.29.188.186.domain: 1+ A? www.microsoft.com. (35)
17:09:34.035748 eth1 > PPPoE  [ses 0x2103]
user-2iniahq.dialup.mindspring.com.1048 > 207.29.188.186.domain: 1+ A?
www.microsoft.com. (35)
17:09:34.418685 eth1 < PPPoE  [ses 0x2103] jfk3-core1-h4-1-0.4.atlas.digex.net
> user-2iniahq.dialup.mindspring.com: icmp: time exceeded in-transit [tos
0xc0]
17:09:34.419192 ppp0 < jfk3-core1-h4-1-0.4.atlas.digex.net >
user-2iniahq.dialup.mindspring.com: icmp: time exceeded in-transit [tos 0xc0]
17:09:34.419403 eth0 > jfk3-core1-h4-1-0.4.atlas.digex.net > 10.0.0.2: icmp:
time exceeded in-transit [tos 0xc0]
17:09:35.044709 eth0 < 10.0.0.2.1048 > 207.29.188.185.domain: 1+ A?
www.microsoft.com. (35)

I've cut it off there; it just goes on like that. I don't really know what any
of this means, but I have a hunch it's significant: something is indeed
reaching the outside world from the Windows machine, but I don't get a good
response back.

Other pertinent config stuff:

[root@woodenspoon init.d]# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:03:6D:1D:60:A2
          inet addr:10.0.0.1  Bcast:10.255.255.255  Mask:255.0.0.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:20705 errors:0 dropped:0 overruns:0 frame:0
          TX packets:17047 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100
          Interrupt:10 Base address:0xf800

eth1      Link encap:Ethernet  HWaddr 00:03:6D:1D:60:9F
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2587 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2686 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100
          Interrupt:11 Base address:0xf400

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:22 errors:0 dropped:0 overruns:0 frame:0
          TX packets:22 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0

ppp0      Link encap:Point-to-Point Protocol
          inet addr:165.121.43.68  P-t-P:165.121.43.1  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1492  Metric:1
          RX packets:3 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:3

[root@woodenspoon init.d]# iptables -t nat --list
Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination

Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination
MASQUERADE  all  --  anywhere             anywhere

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

// (I'm using the ruleset from the HOWTO)

[root@woodenspoon init.d]# cat /proc/sys/net/ipv4/ip_forward
1

[root@woodenspoon init.d]# netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt
Iface
165.121.43.1    0.0.0.0         255.255.255.255 UH       40 0          0 ppp0
10.0.0.0        0.0.0.0         255.0.0.0       U        40 0          0 eth0
127.0.0.0       0.0.0.0         255.0.0.0       U        40 0          0 lo
0.0.0.0         165.121.43.1    0.0.0.0         UG       40 0          0 ppp0

Any ideas? Thanks a lot for any help!

Jyrinx
[EMAIL PROTECTED]

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