ssh through vista connection sharing not working, delayed acks fromclent.

I am trying to access a remote computer using ssh, but get no
response. Using strace, I see the client opening a socket to the
server, setting keep-alive, and hanging in the very first read system
call.

The general connectivity is in place, I browsed http://www.nytimes.com
without problems.

The ssh client is a linux (debian lenny) laptop. I am snooping the
connection with wireshark, and I see the response from the ssh server,
saying "SSH-2.0-OpenSSH_5.1\r\n". Then I see eight retransissions of
this datagram, and finally a FIN followed by a FIN-ACK response. There
is never an ACK response from my laptop, other than the final FIN-ACK.
Also the connection establishment itself looks strange, with multiple
retransmissions:

source: message:
client SYN
server SYN,ACK 70 ms response time
client SYN 3 seconds after the first SYN
server SYN,ACK 70 ms
server SYN,ACK retransmission 15 ms after previous

repeat the last three datagrams with increasing delays, 6 seconds, 12
seconds between tries. Then 24 seconds after last try,

client SYN
server SYN,ACK
client SYN,ACK 0,1 ms delay -- NB this is an ACK reponse
from my client
server "SSH-2.0-OpenSSH_5.1\r\n" (21 bytes) 70 ms
server retransmission of last message X 8
server FIN,ACK Seq=22, ack=21
client FIN,ACK Seq=1, ack=1 1270 seconds after server FIN

I checked the iptables state using iptables -v -L; got policy ACCEPT
and no rules on all chains. Same for tables nat, mangle, and raw.

Yet I could browse the internet.

The network topology is as follows.

I connect to the internet from a Vista laptop, using a wireless. The
linux laptop is connected to the Vista laptop using an ethernet cable.
Connection sharing is turned on in the Vista. I run putty (windows
telent/ssh client) on Vista and connect successfully to the ssh server
in question. I run wireshark on both laptops, snooping the ethernet
interface and see exactly the same datagrams.

What am I missing?

Thanks

On Nov 14, 12:41*pm, Cacadril <en...@online.no> wrote:
> I am trying to access a remote computer using ssh, but get no
> response. Using strace, I see the client opening a socket to the
> server, setting keep-alive, and hanging in the very first read system
> call.
>
> The general connectivity is in place, I browsedhttp://www.nytimes.com
> without problems.
>
> The ssh client is a linux (debian lenny) laptop. I am snooping the
> connection with wireshark, and I see the response from the ssh server,
> saying "SSH-2.0-OpenSSH_5.1\r\n". Then I see eight retransissions of
> this datagram, and finally a FIN followed by a FIN-ACK response.

I found something: All response datagrams, i.e., all datagrams issued
by the remote server, arrive at my linux box with an 802.1q "header"
inserted between the ethernet header and the ip header. I guess this
is something Vista introduces, see the quoted topology description
below. I will start a new thread to ask about this.

> There
> is never an ACK response from my laptop, other than the final FIN-ACK.

Not exactly correct, as there is an ack after a very long time delay.
This is also apparent in the quoted list of exchanges below.

> Also the connection establishment itself looks strange, with multiple
> retransmissions:
>
> * source: * *message:
> * client * * * SYN
> * server * * *SYN,ACK * * 70 ms response time
> * client * * * SYN * * * * * * 3 seconds after the first SYN
> * server * * *SYN,ACK * * 70 ms
> * server * * *SYN,ACK * * retransmission 15 ms after previous
>
> repeat the last three datagrams with increasing delays, 6 seconds, 12
> seconds between tries. Then 24 seconds after last try,
>
> * client * * SYN
> * server * *SYN,ACK
> * client * * SYN,ACK * * 0,1 ms delay * -- NB this is an ACK reponse
> from my client
> * server * *"SSH-2.0-OpenSSH_5.1\r\n" * *(21 bytes) *70 ms
> * server * *retransmission of last message X 8
> * server * *FIN,ACK *Seq=22, ack=21
> * client * * FIN,ACK *Seq=1, ack=1 * *1270 seconds after server FIN
>
> I checked the iptables state using iptables -v -L; got policy ACCEPT
> and no rules on all chains. *Same for tables nat, mangle, and raw.
>
> Yet I could browse the internet.
>
> The network topology is as follows.
>
> I connect to the internet from a Vista laptop, using a wireless. The
> linux laptop is connected to the Vista laptop using an ethernet cable.
> Connection sharing is turned on in the Vista. I run putty (windows
> telent/ssh client) on Vista and connect successfully to the ssh server
> in question. I run wireshark on both laptops, snooping the ethernet
> interface and see exactly the same datagrams.
>
> What am I missing?
>
> Thanks