[tor-relays] max TCP interruption before Tor circuit teardown?

[Gordon Morehouse]

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David Serrano:
> On 2013-10-27 12:29:33 (-0700), Gordon Morehouse wrote:
>> 
>> I've implemented these and I'd really love for anyone who's great
>> at
>>  iptables to sanity-check my rules[1] because I am an iptables
>> relative
>>  noob.
>> 
> 
>> 5: # TODO: don't know if fail2ban will override this if a host
>> with established
>>  6: # connections gets temp banned. We don't want it to. Need to
>> find out.
>> 
> 
> It depends on the spot fail2ban inserts the new firewall rules. If
> it's before
>  the '--state ESTABLISHED' rule, then the ban will be enforced.
> Otherwise, the
>  kernel will let the packets through when they reach that rule.


Here's my 'iptables -L' output, on pastebin because it's a mess when
formatted for email:  http://pastebin.com/f1VZNeTF

That's not a fresh boot, though, I did:

'iptables -F'
'service fail2ban reload'

and then ran the iptables commands by hand, in order.


>> 12: iptables -A INPUT -p tcp -m multiport --dports 31923,31924 -m
>> state --state NEW -j SYN_THROTTLE
>>  [...]
>>  17: /sbin/iptables -A SYN_THROTTLE -m state --state NEW -j LOG
>>  18: /sbin/iptables -A SYN_THROTTLE -m state --state NEW -j
>> REJECT
>> 
> 
> You don't need '-m state --state NEW' in lines 17 and 18 because
> all packets in that chain are already known to be new.

Ah, right - thanks! That might save a few cycles, assuming iptables
wouldn't optimize it out.  Important for the Raspberry Pi!

> I recommend to use always --log-prefix for easy future grepping.

Another good idea, thanks again.  I've committed these changes to the
repo.

Best,
- -Gordon M.


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