Robert Moskowitz wrote:
>I just got Shorewall up and running on a Centos box with the aid of Webmin.
>
>I have the luxury of 64 public addresses and thus both sides of this
>firewall have routable addresses.  No NATing! (I am a co-author of RFC
>1918).
>
>This particular firewalls' life purpose is protecting my Asterisk
>servers (one is also an NTP server).  I **thought** I was setting up the
>rules right.  It looks like I have a SIP registration with my VoIP
>provider (Broadvoice), but calling is not working.  Here is what I have:
>
>cat interfaces
>#
>Pub     eth0    detect
>VoIP    eth1    detect
>
>
>cat zones
>#
>fw      firewall
>Pub     ipv4                            #
>VoIP    ipv4                            #
>
>cat cat rules
>#
>#SECTION ESTABLISHED
>#SECTION RELATED
>SECTION NEW
>ACCEPT  all     all     icmp
>ACCEPT  all     all     udp     53
>ACCEPT  Pub     VoIP    tcp     80
>ACCEPT  Pub     VoIP    tcp     443
># SIP on UDP port 5060. Other SIP servers may need TCP port 5060 as well
>ACCEPT  all-    all-    udp     5004:5082

I would suggest limiting that to just dport 5060.

>ACCEPT  all-    all-    tcp     5060

I've never heard of SIP using TCP

># RTP - the media stream
>ACCEPT  all-    all-    udp     10000:20000

I would cut that down a bit - do you really need 10,000 simultaneous 
call capacity ! Don't forget to alter /etc/asterisk/rtp.conf (IIRC) 
to suit. Also, start at 10001 not 10000 as that is used for Webmin.

># IAX2- the IAX protocol
>ACCEPT  all-    all-    udp     4569
># IAX - most have switched to IAX v2, or ought to
>ACCEPT  all-    all-    udp     5036

Do you have AIX configured and in use - if not then I'd leave that rule out.

>
>See anything obvious here?  Other than wireshark on the firewall, how
>might I figure out what is being blocked?  All I get is a fast busy on a
>call.

I would also suggest being more specific with your rules - all to all 
is generating rules for stuff you may not need/want. I personally 
favour listing specific servers unless there are a few - so only 
traffic to known servers gets allowed. The params file is useful for 
creating names that can be used in the rules files - eg $AstBoxes 
instead of listing Ip addresses.

>On a related note, I want a low-overhead reporting on usage and
>through-put on this firewall.   The box is low end (per /proc/cpuinfo -
>bogomips        : 731.66, and 256Mb memory) and I don't want to steal
>cycles from the voice traffic to measure any firewall induced voice
>degradation.

See /etc/shorewall/accounting.

You can quickly set up some rules to count traffic, and it's then 
fairly simple to knock up a script to read the counters (I find 
"iptables -L account-ip -vxn" gives a reasonably parsable output), 
you may need to change account-ip to whatever your accounting chain 
is called. I feed the results into an rrd database and graph things 
from there.

It doesn't take a lot of overhead to do.

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