On 11/16/2020 12:34 PM, Łukasz Czerpak wrote:
> Hi,
> 
> I've been struggling to setup filtering on a bridge interface. When I
> added "routeback=0", shorewall started blocking communication on the
> bridge. Then I added rules to allow certain connections and Shorewall
> processes them when building iptables script, but it still doesn't work
> (connections are blocked).
> 
> Here is my setup:
> 
> **interfaces:**
> 
> net     eth0 dhcp,tcpflags,nosmurfs,routefilter,logmartians,sourceroute=0
> lxd     lxdbr0
> dhcp,tcpflags,nosmurfs,routefilter,logmartians,bridge,routeback=0
> 
> 
> **policy:**
> 
> lxd     net             ACCEPT
> fw      net             ACCEPT
> fw      lxd             ACCEPT
> net     all             DROP            $LOG_LEVEL
> all     all             REJECT          $LOG_LEVEL
> 
> 
> **relevant fragment from rules:**
> 
> # access to mysql database from containers
> ACCEPT          lxd             lxd:$DB_IP     tcp     mysql
> 
> **some traces from Shorewall's execution:**
> 
> # shorewall trace restart -c 2>&1 | grep mysql
> IN===> ACCEPT          lxd             lxd:10.0.0.11     tcp     mysql
> 
> # shorewall -vv restart -c | grep lxd-lxd
>    Policy ACCEPT from lxd to lxd using chain lxd-lxd
>    Chain lxd-lxd deleted
> 
> **Sample log line:**
> 
> kernel: FORWARD REJECT IN=lxdbr0 OUT=lxdbr0 PHYSIN=veth17392b4a
> PHYSOUT=veth7e32a5a5 MAC=00:16:3e:24:31:30:00:16:3e:51:d6:59:08:00
> SRC=10.0.0.13 DST=10.0.0.11 LEN=60 TOS=0x10 PREC=0x00 TTL=64 ID=30577 DF
> PROTO=TCP SPT=54706 DPT=3306 WINDOW=64240 RES=0x00 SYN URGP=0
> 
> 
> What I do not understand is the following:
> - why lxd-lxd policy is ACCEPT (I haven't defined it explicitly anywhere..)
> - why lxd-lxd chain is deleted (although have a gut feeling it's
> consequence of the above)
> 
> When I add iptables rule manually it all works fine. I have no idea why
> I can't get it workin in Shorewall, it's simple setup :(
> If anyone have any suggestion on how to troubleshoot further, or how to
> fix it, I would very appreciate any such help.
> 

Are you using lxd firewall capabilities (1)?:
- If yes, This is unlikely to work as Shorewall will probably modify
what is created by lxd
- If no, have you looked at (2)

1)  https://lxd.readthedocs.io/en/latest/networks/
2)  https://shorewall.org/bridge-Shorewall-perl.html

-- 
Matt Darfeuille <[email protected]>
Community: https://sourceforge.net/p/shorewall/mailman/message/37107049/
SPC: https://sourceforge.net/p/shorewall/mailman/message/36596609/
Homepage: https://shorewall.org


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