ssh connects to originating host

[Christopher K. Johnson]

Geoffrey Leach wrote:
> Two systems A and B, connected via wireless. A and B both have the same 
> /etc/hosts. Connecting from B to A, "ssh A", works fine. However on A, 
> "ssh B" logs me into A. This used to work fine; the only clue I have is 
> that ssh did not like the stored RSA key. I let it fix it, and that's 
> when the trouble started. Rebooting A did not fix, nor did removing the 
> saved key and repeating.
>
> Any suggestions?
>
> Thanks.
>
>
>   
My best guess:
The stored key issue was symptomatic of the problem resolving host to ip 
address incorrectly.

There are three things to check:
1) Logged on at host A, what does 'host B' command return for 
information?  Is it the correct address for B?  If the wrong address 
then you need to research whether your dns server or an /etc/hosts entry 
is the cause.
2) Whatever user you do this as on host A, is there a ~/.ssh/config 
file?  And if so, does it have a stanza that defines how to contact host 
B, but do so with the wrong name or ip address?
3) It is also possible, but less likely, that on host A you have dnat 
rules in iptables causing the endpoint for that ssh tcp connection to be 
changed to a local host based address.

Chris