Re: [gentoo-user] Proxy server problem

[Mick]

On Sunday 25 Aug 2013 11:13:07 Grant wrote:
> >> >> I set up squid on a remote system so I can browse the internet from
> >> >> that IP address.  It works but it stalls frequently.  I had similar
> >> >> results with ziproxy.  I went over this with the squid list but we
> >> >> got nowhere as it seems to be some kind of a system or network
> >> >> problem.
> >> >>
> >> >> http://squid-web-proxy-cache.1019090.n4.nabble.com/squid-3-3-5-hangs-> >> >> the -en tire-system-td4660893.html
> >> >>
> >> >> Can anyone here help me figure out what is wrong?  I'm not sure where
> >> >> to start.
> >> >>
> >> >> - Grant
> >> >
> >> > Just a quick pointer in case it applies to you:  if you tunnel into
> >> > the proxy machine (using ssh, VPN, proxychains and what not) you
> >> > would suffer from packet fragmentation, which could quickly snowball.
> >> >  In this case try reducing your mtu to lower values, than the default
> >> > ethernet 1500 byte packets, to cater for the overhead of the larger
> >> > tunnelling headers.
> >>
> >> I've tried disconnecting from my SSH tunnel and changing the mtu on my
> >> laptop and on the remote proxy server via ifconfig and there is some
> >> kind of an improvement but I can't narrow it down.  I've tried mtu
> >> down to 1000 on both systems but the proxy server still stalls
> >> sometimes.  Any tips for narrowing this down further?
> >>
> >> - Grant
> >
> > Now that you mentioned using ssh, I don't think that you can improve
> > this.  An mtu at 1000 bytes is lower than I thought might have helped.
> > The problem is caused by stacking tcp packets (tcp within tcp) each of
> > which is using its own timeout for failed fragments.
>
> I think I may have misunderstood you.  I do SSH into the machine
> running squid, but I don't tunnel through that connection in order to
> use the proxy.  I connect to the remote squid instance directly via my
> browser and I also happen to SSH into the same machine to run
> commands.  Do any of your recommendations apply in this scenario?

Ahh!  I misunderstood your set up too.  The problem I described only applies 
to setting up an application layer tunnel (e.g. SSH) and running tcp within 
that secure tunnel.  In your case, you establish a direct connection to your 
server over http or https and a separate connection using SSH.  No tunnelling 
involved and no tcp stacking.

Sorry for the bum steer.

Is this stalling problem happening when you just browse the internet, visiting 
websites, or do you get it when you are downloading large files such as 
videos, or music?  If it is the former, then I am not sure what causes it.  If 
it is the latter, then this may be relevant to http timeout settings. 

I don't have in depth knowledge of this, other than increasing timeout and 
data rates from default values on a hosted server to avoid this problem 
(apache's mod_reqtimeout).  Eventually, I ended up using ftp to download large 
files, instead of http.
-- 
Regards,
Mick