I haveing something wierd going on, can't seem to figure why. I have two
private networks (neta & netb), being masq'ed behind RH 7.3
machines(east & west). I also have iptables running on both machines. I
could ping from west to east anytime with no problem, but when I try to
ping from east to west, it doesn't go through unless I first ping from
west to east (hoepfully this is understandable the way I'm descibing
it). Here is my setup:
------ ------------ ------------ ------
neta---|east|---|dsl router|--internet---|dsl router|--|west|--netb
------ ------------ ------------ ------
internal infaces on linux boxes eth0 on x.x.x.1neta=192.168.0.0/24
netb=192.168.1.0/24ip rules on east:
# ip tunnel add netb mode gre remote a.b.c.e local f.g.h.i ttl 255
# ip link set netb up arp on
# ip addr add 192.168.0.254/24 dev netb
# ip route add 192.168.1.0/24 dev netb
ip rules on west:
# ip tunnel add neta mode gre remote f.g.h.i local a.b.c.e ttl 255
# ip link set neta up arp on
# ip addr add 192.168.1.254/24 dev neta
# ip route add 192.168.0.0/24 dev neta
[east]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
a.b.c.w 0.0.0.0 255.255.255.248 U 0 0 0 eth0
192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 netb
192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 netb
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
0.0.0.0 a.b.c.x 0.0.0.0 UG 0 0 0 eth0
[west]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
f.g.h.y 0.0.0.0 255.255.255.248 U 0 0 0 eth0
192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 neta
192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 neta
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
0.0.0.0 f.g.h.z 0.0.0.0 UG 0 0 0 eth0
Iptables are the same on both boxes except on east I open allow ports 25
80 443 and specifically block port 1003.
If I'm listening on west at neta when I first try to ping anyone on
netb, nothing is coming though unless I have just pinged from netb to
neta first.
Hopefully this isn't too confusing or long winded.
TIA
Steve