i have some problems connecting to my pi from my pc. i am using a ethernet cable to connect to my pi througg ssh. But my problem is that i cannot always stablish a connection. When i use arp -a in cmd i can sometimes see the ip adress for my pi but when i try to ping it it says host unreachable. i am not sure but i think it has something to do with my pc i am using windows 7. Can anyone help me. thanks
It could mean that you are pinging the wrong IP address. If you are using dhcp your router may well have allocated it a different IP address.
One way of finding out is to log into your router and see which IP addresses have been allocated. While you are there it is a good idea to give static addresses to any computers that are always at that location (assuming soho environment) Alternatively use a Windows command I think that one of these might do it:
From a Linux computer the command is:
nmap -sP 192.168.1.0/24
These should show a list of all computers on your network (assuming it is using 192.168.1.0 as the network
If the computer in question does not show up reboot it. If it still does not show up it is most likely a hardware problem. Check the cables (substitute them if possible) and look at the lights on the router.
Host unreachable would mean that either the Pi has frozen, or the Pi's ethernet interface has been taken down.
When the ping says host unreachable, plug a screen and keyboard into the Pi so you can run ifconfig to check the status of eth0
If eth0 is not UP or the Pi is frozen, that would be why you cannot ssh into the Pi.