Bob Metelsky
2007-Nov-17 00:25 UTC
[CentOS] Basic Network question pinging different subnets
Hi Im a little perplexed by this situation
I have centos 4.5 installed on 2 pcs - each with 2 network cards
machine 1
eth0 Link encap:Ethernet HWaddr 00:14:2A:6B:C8:CC
inet addr:10.54.7.2 Bcast:10.54.7.255 Mask:255.255.255.0
eth1 Link encap:Ethernet HWaddr 00:11:50:9B:A2:90
inet addr:10.54.0.2 Bcast:10.54.0.255 Mask:255.255.255.0
machine 2
eth0 Link encap:Ethernet HWaddr 00:14:2A:69:4C:47
inet addr:10.54.7.3 Bcast:10.54.7.255 Mask:255.255.255.0
eth1 Link encap:Ethernet HWaddr 00:11:50:9B:A5:0A
inet addr:10.54.0.3 Bcast:10.54.0.255 Mask:255.255.255.0
machine 1 & 2 can ping each other on either subnets
machine 3 (windows)...
C:\>ipconfig
Connection-specific DNS Suffix . :
IP Address. . . . . . . . . . . . : 10.54.7.16
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 10.54.7.1
cant ping anything on the 10.54.0 subnet, nor does that subnet show up
ip using a port scanner...
C:\>ping 10.54.0.2
Pinging 10.54.0.2 with 32 bytes of data:
Request timed out.
Request timed out.
C:\>ping 10.54.7.2
Pinging 10.54.7.2 with 32 bytes of data:
Reply from 10.54.7.2: bytes=32 time<1ms TTL=64
Reply from 10.54.7.2: bytes=32 time<1ms TTL=64
Any ideas why this is happening? I dont have a firewall on the 10.54
address,
Thanks
Bob
Scott Silva
2007-Nov-17 00:44 UTC
[CentOS] Re: Basic Network question pinging different subnets
on 11/16/2007 4:25 PM Bob Metelsky spake the following:> Hi Im a little perplexed by this situation > > I have centos 4.5 installed on 2 pcs - each with 2 network cards > > machine 1 > > eth0 Link encap:Ethernet HWaddr 00:14:2A:6B:C8:CC > inet addr:10.54.7.2 Bcast:10.54.7.255 Mask:255.255.255.0 > eth1 Link encap:Ethernet HWaddr 00:11:50:9B:A2:90 > inet addr:10.54.0.2 Bcast:10.54.0.255 Mask:255.255.255.0 > > machine 2 > > eth0 Link encap:Ethernet HWaddr 00:14:2A:69:4C:47 > inet addr:10.54.7.3 Bcast:10.54.7.255 Mask:255.255.255.0 > > eth1 Link encap:Ethernet HWaddr 00:11:50:9B:A5:0A > inet addr:10.54.0.3 Bcast:10.54.0.255 Mask:255.255.255.0 > > > machine 1 & 2 can ping each other on either subnets > > machine 3 (windows)... > > C:\>ipconfig > > Connection-specific DNS Suffix . : > IP Address. . . . . . . . . . . . : 10.54.7.16 > Subnet Mask . . . . . . . . . . . : 255.255.255.0 > Default Gateway . . . . . . . . . : 10.54.7.1 > > cant ping anything on the 10.54.0 subnet, nor does that subnet show up > ip using a port scanner... > > C:\>ping 10.54.0.2 > > Pinging 10.54.0.2 with 32 bytes of data: > Request timed out. > Request timed out. > > C:\>ping 10.54.7.2 > > Pinging 10.54.7.2 with 32 bytes of data: > Reply from 10.54.7.2: bytes=32 time<1ms TTL=64 > Reply from 10.54.7.2: bytes=32 time<1ms TTL=64 > > > Any ideas why this is happening? I dont have a firewall on the 10.54 > address, >Machine 3 is locked to its subnet by the subnet mask. Your above mask of 255.255.255.0 only lets the windows machine talk to 10.54.7.1 through 10.54.7.254. Without adding a route to that other address, or a virtual IP address in that address space, the windows machine can't see or communicate on the other subnet. -- MailScanner is like deodorant... You hope everybody uses it, and you notice quickly if they don't!!!!
Alain Spineux
2007-Nov-17 00:50 UTC
[CentOS] Basic Network question pinging different subnets
On Nov 17, 2007 1:25 AM, Bob Metelsky <bobmetelsky at comcast.net> wrote:> Hi Im a little perplexed by this situation > > I have centos 4.5 installed on 2 pcs - each with 2 network cards > > machine 1 > > eth0 Link encap:Ethernet HWaddr 00:14:2A:6B:C8:CC > inet addr:10.54.7.2 Bcast:10.54.7.255 Mask:255.255.255.0 > > eth1 Link encap:Ethernet HWaddr 00:11:50:9B:A2:90 > inet addr:10.54.0.2 Bcast:10.54.0.255 Mask:255.255.255.0 > > machine 2 > > eth0 Link encap:Ethernet HWaddr 00:14:2A:69:4C:47 > inet addr:10.54.7.3 Bcast:10.54.7.255 Mask:255.255.255.0 > > eth1 Link encap:Ethernet HWaddr 00:11:50:9B:A5:0A > inet addr:10.54.0.3 Bcast:10.54.0.255 Mask:255.255.255.0 > > > machine 1 & 2 can ping each other on either subnets > > machine 3 (windows)... > > C:\>ipconfig > > Connection-specific DNS Suffix . : > IP Address. . . . . . . . . . . . : 10.54.7.16 > Subnet Mask . . . . . . . . . . . : 255.255.255.0 > Default Gateway . . . . . . . . . : 10.54.7.1 > > cant ping anything on the 10.54.0 subnet, nor does that subnet show up > ip using a port scanner... > > C:\>ping 10.54.0.2 > > Pinging 10.54.0.2 with 32 bytes of data: > Request timed out. > Request timed out. > > C:\>ping 10.54.7.2 > > Pinging 10.54.7.2 with 32 bytes of data: > Reply from 10.54.7.2: bytes=32 time<1ms TTL=64 > Reply from 10.54.7.2: bytes=32 time<1ms TTL=64 > > > Any ideas why this is happening? I dont have a firewall on the 10.54 > address,Yes ! You have to learn how works IP networks :-) IP is wild and wide :-) you can try this on your windows : c:\> route add 10.54.0.2 MASK 255.255.255.255 10.54.7.2 OR do the same on your router at 10.54.7.1 OR (depend on how your linux box is configured) c:\> route add 10.54.0.0 MASK 255.255.255.0 10.54.7.16 But this should give you access on both 10.54.0.2 and 10.54.0.3 OR if routing is enable on 10.54.7.2 c:\> route add 10.54.0.0 MASK 255.255.255.0 10.54.7.2 should also give you access to both 10.54.0.2 and 10.54.0.3 You just have to understand the first one other are just to spread out my IP knowledges. Ops, the last one is sometime useful to configure a device on another IP range, without reconfiguring your IP. Like when unpacking a new router with IP 192.168.123.1 Regards.> > Thanks > Bob > > > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos >-- Alain Spineux aspineux gmail com May the sources be with you
John R Pierce
2007-Nov-17 01:11 UTC
[CentOS] Basic Network question pinging different subnets
Bob Metelsky wrote:> Hi Im a little perplexed by this situation > > I have centos 4.5 installed on 2 pcs - each with 2 network cards > > machine 1 > > eth0 Link encap:Ethernet HWaddr 00:14:2A:6B:C8:CC > inet addr:10.54.7.2 Bcast:10.54.7.255 Mask:255.255.255.0 > eth1 Link encap:Ethernet HWaddr 00:11:50:9B:A2:90 > inet addr:10.54.0.2 Bcast:10.54.0.255 Mask:255.255.255.0 > > machine 2 > > eth0 Link encap:Ethernet HWaddr 00:14:2A:69:4C:47 > inet addr:10.54.7.3 Bcast:10.54.7.255 Mask:255.255.255.0 > > eth1 Link encap:Ethernet HWaddr 00:11:50:9B:A5:0A > inet addr:10.54.0.3 Bcast:10.54.0.255 Mask:255.255.255.0 > > > machine 1 & 2 can ping each other on either subnets >so you have two seperate networks? the eth0's are connected to one hub or switch, and the eth1's to another hub or switch?> machine 3 (windows)... > > C:\>ipconfig > > Connection-specific DNS Suffix . : > IP Address. . . . . . . . . . . . : 10.54.7.16 > Subnet Mask . . . . . . . . . . . : 255.255.255.0 > Default Gateway . . . . . . . . . : 10.54.7.1 > > cant ping anything on the 10.54.0 subnet, nor does that subnet show up > ip using a port scanner... > > C:\>ping 10.54.0.2 > > Pinging 10.54.0.2 with 32 bytes of data: > Request timed out. > Request timed out. > > C:\>ping 10.54.7.2 > > Pinging 10.54.7.2 with 32 bytes of data: > Reply from 10.54.7.2: bytes=32 time<1ms TTL=64 > Reply from 10.54.7.2: bytes=32 time<1ms TTL=64 > > > Any ideas why this is happening? I dont have a firewall on the 10.54 > address,presumably, the windows machine is connected to the 'eth0' network that the centos machines are connected to? how exactly do you expect the packets to get from there to the other network? the windows machine has been instructed to forward all unknown packets to 10.54.7.1, which presumably is some other sort of router... chances are, said 10.54.7.1 has no clue where 10.54.0.xxx is. solution 1) configure a linux computer to do 'ip forwarding', and give the windows machine a route like... C> route add 10.54.0.0 mask 255.255.255.0 gw 10.54.7.2 or, solution 2) configure the router at 10.54.7.1 to have a route to this other network. if both networks are on the same hub/switch, then I can only ask... WHY?