Re: Unreliable TCP?

[Valdis . Kletnieks]

On Sat, 19 Mar 2005 21:59:16 EST, Ioan Ionita said:

> applications which use the UDP protocol.  However, certain firewalls
> don't allow UDP traffic, therefore I tried UDP over TCP as a
> workaround.

That's the firewall's problem, not yours.  There's very few firewalls
that prohibit *all* UDP traffic (for starters, DNS becomes interesting).
Usually a firewall stops *most* UDP traffic only because the firewall admin
has decided that there's few UDP-based applications that they want to allow
through...

Explain why you think that your application will be let through the firewall
if it's TCP-based?  If the firewall admin thinks enough of your application to
open a port, it's equally likely to get you an open UDP port.

(For bonus points, work out the ethics of trying to circumvent a firewall that's
there for presumably good reasons - the people who installed the firewall did so
because they only want to allow certain traffic through.  Having the user
ask "Can I have port 99343 opened so application XYZ works?" is much more likely
to be useful *LONG-TERM* than getting into a long-term pissing match with the
firewall admin, who gets upset at your attempts to bypass his firewall and
starts playing whack-a-mole.  If you *do* get UDP-over-TCP working, you're
looking at having to move the port around all the time because it will get
blocked...)

>                                             So I was wondering if
> there's any way to disable the whole reliability checking of TCP in
> the linux kernel. Maybe configure the kernel to never request the
> retransmission of a packet, even if it detects packet loss/bad order?

Yes, it's called UDP. :)

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