very strange network problem.

bruse · 09-26-2005, 01:59 AM

just think two system 10.255.240.230 and 10.255.240.102 are in network.
i can connect system 10.255.240.230 to system 10.255.240.102.
but i can not connect system B to system A but i can ping a system.

[root@localhost root]# ssh 10.255.240.230
ssh: connect to host 10.255.240.230 port 22: no route to host.
[root@localhost root]# ping 10.255.240.230
PING 10.255.240.230 (10.255.240.230) 56(84) bytes of data.
64 bytes from 10.255.240.230: icmp_seq=1 ttl=64 time=0.504 ms
64 bytes from 10.255.240.230: icmp_seq=2 ttl=64 time=0.500 ms
64 bytes from 10.255.240.230: icmp_seq=3 ttl=64 time=0.497 ms
64 bytes from 10.255.240.230: icmp_seq=4 ttl=64 time=0.494 ms
64 bytes from 10.255.240.230: icmp_seq=5 ttl=64 time=0.498 ms

--- 10.255.240.230 ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 3996ms
rtt min/avg/max/mdev = 0.494/0.498/0.504/0.024 ms
[root@localhost root]#

but system 10.255.240.230 can ssh to 10.255.240.102.
and ftp telnet samba nothing is working other than the ping.

how to tackle this issue.?

m0rg · 09-26-2005, 02:05 AM

have you checked that sshd is running on the computer you can't connect to?

bruse · 09-26-2005, 02:16 AM

see i can connect an other system too. so it means sshd running on both the machines.and this is not only the case. ftp telnet samba NFS are not working.
so obviously there is a problem in internaly.

now my question is how to handle this issue.?

Snowbat · 09-26-2005, 06:23 AM

Did you review the firewall configuration on both systems?

bruse · 09-27-2005, 07:05 AM

i have stopped all the firewall's.but still not working.
it seems that there is a route config problem.

bruse · 09-27-2005, 07:11 AM

i have stopped all the firewall's.but still not working.
it seems that there is a route config problem.

linuxmanju · 09-27-2005, 10:57 AM

what is the subnet mask assigned to both ?

bruse · 09-28-2005, 04:29 AM

the ip address is 10.255.240.xxx so that ...

Mask:255.255.240.0

Snowbat · 09-28-2005, 04:54 AM

That netmask covers 10.255.240.0 - 10.255.255.255 - a large subnet but if you've configured ALL your equipment to use that netmask, it shouldn't be a problem.

What is the output of /sbin/route on machine 10.255.240.102? It is very strange that this machine can ping 10.255.240.230 but ssh reports no route to that host.

bruse · 09-28-2005, 05:33 AM

[student@localhost student]$ /sbin/route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.1.0 * 255.255.255.0 U 0 0 0 eth0
10.255.240.0 * 255.255.240.0 U 0 0 0 eth0
127.0.0.0 * 255.0.0.0 U 0 0 0 lo
default 10.255.240.1 0.0.0.0 UG 0 0 0 eth0
[student@localhost student]$

Snowbat · 09-28-2005, 06:59 AM

I think the second entry may be causing problems. Why is it there?
What is the output of /sbin/ifconfig eth0 on this machine?

bruse · 09-28-2005, 07:10 AM

debian:~# /sbin/ifconfig eth0
eth0 Link encap:Ethernet HWaddr 00:11:09:17:3D:87
inet addr:10.255.240.102 Bcast:10.255.255.255 Mask:255.0.0.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:18153 errors:0 dropped:0 overruns:0 frame:0
TX packets:460 errors:0 dropped:0 overruns:0 carrier:0
collisions:18 txqueuelen:1000
RX bytes:1320793 (1.2 MiB) TX bytes:112756 (110.1 KiB)
Interrupt:23 Base address:0xc000

debian:~#

should my route match with that system ?

Snowbat · 09-28-2005, 07:45 AM

Well, the interface uses netmask 255.0.0.0.

Try this and then check if ssh works:
route del -net 192.168.1.0 netmask 255.255.255.0 eth0
route del -net 10.255.240.0 netmask 255.255.240.0 eth0

If you have some reason for the 192.168.1.0 routing entry, you can probably put it back in (I *think* it won't cause problems) but the 10.255.240.0 entry is certainly redundant given your default route.
route add -net 192.168.1.0 netmask 255.255.255.0 eth0