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Old 02-29-2016, 03:34 AM   #1
v7-27
LQ Newbie
 
Registered: Feb 2016
Posts: 3

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ubuntu tries send broadcast packets to another network


hi all. help me please.
we have two servers in the different networks: 1st 10.170.0.41/23, 2nd 10.150.0.40/23. they can’t reach each other. i think problem on the 1st server because it have correct ifconfig
Code:
eth0      Link encap:Ethernet  HWaddr 9e:e3:2d:71:d5:f8
          inet addr:10.170.0.41  Bcast:10.170.1.255  Mask:255.255.254.0
correct routes
Code:
root@server1:~# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         10.170.0.254    0.0.0.0         UG    100    0        0 eth0
10.150.0.0      10.170.1.93     255.255.0.0     UG    0      0        0 eth0
10.170.0.0      0.0.0.0         255.255.254.0   U     0      0        0 eth0
BUT!!! it tries send arp packets using broadcast to find server in another network
Code:
root@server1:~# tshark host 10.150.0.40
tshark: Lua: Error during loading:
 [string "/usr/share/wireshark/init.lua"]:45: dofile has been disabled
Running as user "root" and group "root". This could be dangerous.
Capturing on eth0
  0.000000 9e:e3:2d:71:d5:f8 -> Broadcast    ARP 42 Who has 10.150.0.40?  Tell 10.170.0.41
  0.999919 9e:e3:2d:71:d5:f8 -> Broadcast    ARP 42 Who has 10.150.0.40?  Tell 10.170.0.41
  1.999901 9e:e3:2d:71:d5:f8 -> Broadcast    ARP 42 Who has 10.150.0.40?  Tell 10.170.0.41
Code:
root@server1:~# traceroute 10.150.0.40
traceroute to 10.150.0.40 (10.150.0.40), 30 hops max, 60 byte packets
 1  10.170.0.41 (10.170.0.41)  1564.138 ms !H  1564.124 ms !H *
it thinks that 2nd server in the same network

P.S. 1st server can reach any servers in network of the 2nd server

Thank you for the help

Last edited by v7-27; 03-07-2016 at 07:53 AM.
 
Old 02-29-2016, 12:51 PM   #2
smallpond
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Location: Massachusetts, USA
Distribution: Fedora
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What's the output of:
Code:
ip route get to 10.150.0.40
 
Old 03-02-2016, 05:56 AM   #3
v7-27
LQ Newbie
 
Registered: Feb 2016
Posts: 3

Original Poster
Rep: Reputation: Disabled
Unfortunately i restarted this server. and problem disappeared. but the same problem on another pair of servers
i try to reach 10.150.10.42 from 10.170.0.51/23
Code:
root@server1:~# ifconfig
eth0      Link encap:Ethernet  HWaddr 76:a7:c4:0a:2a:b2
          inet addr:10.170.0.51  Bcast:10.170.1.255  Mask:255.255.254.0
Code:
root@server1:~# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         10.170.0.254    0.0.0.0         UG    100    0        0 eth0
10.150.0.0      10.170.1.93     255.255.0.0     UG    0      0        0 eth0
10.170.0.0      0.0.0.0         255.255.254.0   U     0      0        0 eth0
but it try to find destination in its network
Code:
root@server1:~# tshark host 10.150.10.42
tshark: Lua: Error during loading:
 [string "/usr/share/wireshark/init.lua"]:45: dofile has been disabled
Running as user "root" and group "root". This could be dangerous.
Capturing on eth0
  0.000000 76:a7:c4:0a:2a:b2 -> Broadcast    ARP 42 Who has 10.150.10.42?  Tell 10.170.0.51
Code:
root@server1:~# traceroute 10.150.10.42
traceroute to 10.150.10.42 (10.150.10.42), 30 hops max, 60 byte packets
 1  10.170.0.51 (10.170.0.51)  3001.882 ms !H  3001.870 ms !H  3001.854 ms !H
this is a command which you asked

Code:
root@server1:~# ip route get to 10.150.10.42
10.150.10.42 dev eth0  src 10.170.0.51
    cache <redirected>  rtt 89ms rttvar 59ms cwnd 28
p.s. both servers with the problem in one network and running on xen server. the problem exists in pair: from one source to one destination

Last edited by v7-27; 03-07-2016 at 07:56 AM.
 
  


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