Re: routing

[Sthu Deus <sthu.deus@gmail.com>]

Thank You for Your time and answers, Jesús - I really appreciate it:

> Two things:
> 1) Try without a firewall (iptables default rules 
> to "accept",  /proc/sys/net/ipv4/ip_forward to "1" and anything else).

Still the same:

Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source
destination 19  2300 ACCEPT     all  --  *      *
0.0.0.0/0            0.0.0.0/0           state RELATED,ESTABLISHED
0     0 ACCEPT     tcp  --  lo     *       0.0.0.0/0
0.0.0.0/0           tcp

Chain FORWARD (policy ACCEPT 20 packets, 1680 bytes)
 pkts bytes target     prot opt in     out     source
destination

Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source
destination 26  1688 ACCEPT     all  --  *      *
0.0.0.0/0            0.0.0.0/0           state RELATED,ESTABLISHED
0     0 ACCEPT     all  --  *      *       0.0.0.0/0
0.0.0.0/0           state NEW

For /proc/sys/net/ipv4/ip_forward I tried numbers 1, 2, 3 - all w/ the
same effect - packets go to but do no return.

I see them going by ppp - to one direction only - just like it was w/
the previous iptables configuration.
 
> 2) Then if you can ping 20.20.20.20 from host1 *and* you can ping
> "the Internet" from host2 (say, `ping 152.46.7.81`, which is the IP
> for www.tldp.org, known to return ECHO packages) it's almost surely
> not a routing problem within host2.

I did ping for the IP - same effect - it works for host2 and does not
for host1.

If it be not routing problem, then what it can be?
Though I think it is - in the past times on another installation it did
work and I remember in the routing table was set as

Destination     Gateway         Genmask         Flags Metric Ref    Use
Iface
10.10.10.10 *               255.255.255.255 UH    0
0        0 ppp0
localnet        *               255.255.255.0   U
0      0        0 eth0
link-local      *               255.255.0.0
U     1000   0        0 eth0
default         *
0.0.0.0         U     0      0        0 ppp0

But I do not understand what are the addresses "localnet" and
"link-local" .

> Now, my bet:
> Does whatever sit on the far end of your ppp link holding IP address 
> 10.10.10.10 know how to return packets to 192.168.0.0/24?

Sorry, I do not know. All I know about this is that host2 gets pings it
sends and host1 - does not.

I have tried
ftp 91.121.86.213
w/ the same effect.