Re: [gentoo-user] ssh connections time out

[Dale]

Mick wrote:
> Thank you all for your replies,
>
> On Tuesday 27 November 2007, Chris Frederick wrote:
>
>> Dale wrote:
>>
>
>
>>> I also ran into something like this on a local network.  I corrected
>>> this by adding the remote systems to my hosts file and putting the entry
>>> in the host file on the remote system.
>>>
> [ship...]
>
>
>> I've had this problem as well.  I've added "UseDNS no" to the
>> sshd_config file and that had the same result.  I usually only had high
>> latency establishing the connection though.  Once the connection was
>> established and I was logged in, everything was fast again.
>>
>
> The problem is not with the DNS servers.  I use IP addresses to access these
> machines and when I have tried FQDNs it makes no odds.
>
>
>> I've also had connection issues while transferring files through ssh,
>> and I got around that (somewhat) by added "-l" to the scp command.  This
>> tries to throttle the connection speed, and I can usually keep a
>> connection going with that.  I say that is somewhat fixed the issue
>> because I also need to use ssh to port forward to an internal database
>> and run scripts there, but there's no way that I know to do the same
>> throttling with a port forwarding ssh command.
>>
>
> The -l option is to apply a protocol specific type of QoS and limit the
> bandwidth consumed by scp so that other critical services on the server don't
> run dry.  My problem is that I do not seem to have enough bandwidth to start
> with.
>
> The ports of the servers are random numbers in the 200+ and 12000+ range and I
> have checked that no other applications are using/listening on these ports.
> I've not tried port 22 yet, but I'll give it a go tonight.  I tend to use
> higher random ports just to achieve some basic 'security by obscurity' from
> script kiddies and botnets.  The issue with port 22 is that the
> world-and-his-wife will try to hack in and cause DoS to the little bandwidth
> that seems to be available.  :p  Ha!  I'll deal with this at the firewall.
>
> The datacenter servers are listening on port 22.  This difference in
> performance between the production and the domestic servers also made me
> think that there may well be some traffic shaping by the ISPs at their
> routers, but don't know if I can test this for definite somehow.
>
> I don't think that setting up QoS at the domestic servers is going to make any
> difference.  These machines are not stressed at all and off peak I can access
> them fine.  It is at peak times that things really go pear shape, hence it
> should be a network congestion/traffic shaping issue.  I don't know if people
> started going mad at the pre-Christmas online shopping and things have been
> particularly bad since last Saturday, or if it is just some ISP network
> maintenance that made my connections impossible.
>
> More about my trials and tribulations on port 22 tomorrow . . .
>

Just to add to this, I was using the IP address too and it was very
slow.  This was also on a local network.  After adding the lines to my
host files, it was fast no matter whether I used the name or the IP
address.  I still don't understand why this matters tho.

Just a thought.

Dale

:-)  :-)  :-)