I would guess from your logs that your DomU simply misses a
default route, so it can only send out packets to the 143.215.129.0 network.
 
Try adding a default route in your DomU, e.g. by calling “ip
route add default via $gateway_ip_address dev eth0”. $gateway_ip_address
should be your routing box that connects to outside networks.
 
From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Sarika Ray
Sent: 03 December 2008 06:19
To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] strange networking issue in xen DomU
 
 
 
I have a xen 3.2.0 setup with 2.6.18. XenoLinux kernel and FC8 Dom0 file system. I have
used xen-tools to create a Debian-Etch DomU. 
With the default setup I was not able to  ping to any other host except
Dom0. I guess that was due to forward chaining issue with my Dom0. But then I
modified my iptables configuration in Dom0 to comment out the  forwarding
rule that was rejecting everything. So now I am being able to ping to all the
hosts in the same L3 subnet as my DomU but not not anything other than that.
So could any please tell me what I am doing wrong? I am including some details
below. Let me know if I am missing to provide some necessary information.
**********
my  DomU  config file is as  follows:
#
# Configuration file for the Xen instance dmvirt1.xxx, created
# by xen-tools 3.9 on Tue Dec  2 17:51:45 2008.
#
#
#  Kernel + memory size
#
kernel      = '/boot/vmlinuz-2.6.18.8-xen'
ramdisk     = '/boot/initrd-2.6.18.8-xen.img'
memory      = '128'
#
#  Disk device(s).
#
root        = '/dev/sda2 ro'
disk        = [
                 
'phy:/dev/DomUVols/dmvirt1.xxx-swap,sda1,w',
                 
'phy:/dev/DomUVols/dmvirt1.xxx-disk,sda2,w',
             
]
#
#  Hostname
#
name        = 'dmvirt1.xxxx'
#
#  Networking
#
vif         = [
'ip=143.215.129.1xx,mac=00:16:3E:88:22:AA' ]
vfb = ['type=vnc']
#
#  Behaviour
#
on_reboot   = 'restart'
on_crash    = 'restart'
extra = "xencons=xvc console=xvc console=tty"
*******************
*****************
Some other DomU Details
dmvirt1:~# ifconfig
eth0      Link encap:Ethernet  HWaddr
00:16:3E:88:22:AA  
          inet addr:143.215.129.157  Bcast:143.215.129.255  Mask:255.255.255.0
          inet6 addr:
fe80::216:3eff:fe88:22aa/64 Scope:Link
          UP BROADCAST RUNNING
MULTICAST  MTU:1500  Metric:1
          RX packets:1206 errors:0
dropped:0 overruns:0 frame:0
          TX packets:68 errors:0
dropped:0 overruns:0 carrier:0
          collisions:0
txqueuelen:1000 
          RX bytes:114259 (111.5
KiB)  TX bytes:10024 (9.7 KiB)
lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128
Scope:Host
          UP LOOPBACK
RUNNING  MTU:16436  Metric:1
          RX packets:0 errors:0
dropped:0 overruns:0 frame:0
          TX packets:0 errors:0
dropped:0 overruns:0 carrier:0
          collisions:0
txqueuelen:0 
          RX bytes:0 (0.0 b) 
TX bytes:0 (0.0 b)
dmvirt1:~# route -n
Kernel IP routing table
Destination     Gateway        
Genmask         Flags Metric
Ref    Use Iface
143.215.129.0   0.0.0.0        
255.255.255.0  
U     0     
0        0 eth0
dmvirt1:/etc# cat /etc/network/interfaces 
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
auto eth0
iface eth0 inet static
 address 143.215.129.1xx
 gateway 143.215.129.1
 netmask 255.255.255.0
  broadcast ${broadcast}
 
 # post-up  ethtool -K eth0 tx off
#
# The commented out line above will disable TCP checksumming which
# might resolve problems for some users.  It is disabled by default
#
dmvirt1:~# ping www.yahoo.com
ping: unknown host www.yahoo.com
dmvirt1:~# ping 69.147.76.15
connect: Network is unreachable
*******************
Dom0 Details
[root@kahn dev]# iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt
source              
destination         
RH-Firewall-1-INPUT  all  -- 
anywhere            
anywhere            
Chain FORWARD (policy ACCEPT)
target     prot opt
source              
destination         
ACCEPT     all  -- 
dmvirt1             
anywhere           
PHYSDEV match --physdev-in vif17.0 
ACCEPT     udp  -- 
anywhere            
anywhere           
PHYSDEV match --physdev-in vif17.0 udp spt:bootpc dpt:bootps 
Chain OUTPUT (policy ACCEPT)
target     prot opt
source              
destination         
Chain RH-Firewall-1-INPUT (1 references)
target     prot opt
source              
destination         
ACCEPT     all  -- 
anywhere            
anywhere            
ACCEPT     icmp -- 
anywhere            
anywhere            icmp
any 
ACCEPT     esp  -- 
anywhere            
anywhere            
ACCEPT     ah   -- 
anywhere            
anywhere            
ACCEPT     udp  -- 
anywhere            
224.0.0.251        
udp dpt:mdns 
ACCEPT     udp  -- 
anywhere            
anywhere            udp
dpt:ipp 
ACCEPT     tcp  -- 
anywhere            
anywhere            tcp
dpt:ipp 
ACCEPT     all  -- 
anywhere            
anywhere            state
RELATED,ESTABLISHED 
ACCEPT     tcp  -- 
anywhere            
anywhere           
state NEW tcp dpt:ssh 
ACCEPT     tcp  -- 
anywhere            
anywhere           
state NEW tcp dpt:http 
ACCEPT     tcp  -- 
anywhere            
anywhere            state
NEW tcp dpt:nfs 
ACCEPT     udp  -- 
anywhere            
anywhere           
state NEW udp dpt:nfs 
ACCEPT     tcp  -- 
anywhere            
anywhere           
state NEW tcp dpt:https 
ACCEPT     tcp  -- 
anywhere            
anywhere            state
NEW tcp dpt:domain 
ACCEPT     udp  -- 
anywhere            
anywhere           
state NEW udp dpt:domain 
ACCEPT     tcp  -- 
anywhere            
anywhere           
state NEW tcp dpt:sunrpc 
ACCEPT     tcp  -- 
anywhere            
anywhere           
state NEW tcp dpt:telnet 
ACCEPT     tcp  -- 
anywhere            
anywhere           
state NEW tcp dpt:cvspserver 
ACCEPT     tcp  -- 
anywhere            
anywhere           
state NEW tcp dpts:terabase:pxc-splr-ft 
ACCEPT     udp  -- 
anywhere            
anywhere           
state NEW udp dpts:terabase:pxc-splr-ft 
ACCEPT     tcp  -- 
anywhere            
anywhere           
state NEW tcp dpt:teradataordbms 
REJECT     all  -- 
anywhere            
anywhere           
reject-with icmp-host-prohibited 
[root@kahn dev]# ifconfig
eth0      Link encap:Ethernet  HWaddr
00:1A:A0:1B:88:E1  
          inet
addr:143.215.129.2xx  Bcast:143.215.129.255  Mask:255.255.255.0
          inet6 addr:
fe80::21a:a0ff:fe1b:88e1/64 Scope:Link
          UP BROADCAST RUNNING
MULTICAST  MTU:1500  Metric:1
          RX packets:506521
errors:0 dropped:0 overruns:0 frame:0
          TX packets:165558
errors:0 dropped:0 overruns:0 carrier:0
          collisions:0
txqueuelen:0 
          RX bytes:423458331
(403.8 MiB)  TX bytes:11964484 (11.4 MiB)
lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128
Scope:Host
          UP LOOPBACK
RUNNING  MTU:16436  Metric:1
          RX packets:235929
errors:0 dropped:0 overruns:0 frame:0
          TX packets:235929
errors:0 dropped:0 overruns:0 carrier:0
          collisions:0
txqueuelen:0 
          RX bytes:36772495 (35.0
MiB)  TX bytes:36772495 (35.0 MiB)
peth0     Link encap:Ethernet  HWaddr
00:1A:A0:1B:88:E1  
          inet6 addr: fe80::21a:a0ff:fe1b:88e1/64
Scope:Link
          UP BROADCAST RUNNING
MULTICAST  MTU:1500  Metric:1
          RX packets:553720
errors:0 dropped:0 overruns:0 frame:0
          TX packets:162980
errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:434130358
(414.0 MiB)  TX bytes:13050967 (12.4 MiB)
          Interrupt:20 
vif17.0   Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF  
          inet6 addr:
fe80::fcff:ffff:feff:ffff/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST 
MTU:1500  Metric:1
          RX packets:361 errors:0
dropped:0 overruns:0 frame:0
          TX packets:4092 errors:0
dropped:5 overruns:0 carrier:0
          collisions:0
txqueuelen:32 
          RX bytes:43052 (42.0
KiB)  TX bytes:393229 (384.0 KiB)
[root@kahn dev]# brctl show
bridge name     bridge
id              
STP enabled     interfaces
eth0           
8000.001aa01b88e1      
no             
peth0
                                                       
vif17.0
******************