It may seem like a stupid question (again, I don't know docker) but, are
the VMs' virtual network interfaces, and the host's network interface,
in the same zone?
On 2025-03-20 4:19 a.m., Sean Murphy via Shorewall-users wrote:
Thanks Winston - I had hoped to avoid getting my hands dirty with tcpdump but it
looks like I might have to. Do you find it straightforward to track movements
through
the chains and tables with tcpdump?
The client runs in a docker container - my main objective is to use curl from
within a docker
container as the client and a http server running on the host but I've also
been trying it
out with and ssh client and a ping client (both working inside the container).
We have basically 3 zones: the firewall zone, the network zone and the docker
zone.
The firewall zone is as defined by shorewall. The network zone refers to
traffic on the
(single) network interface and the docker zone refer to traffic originating and
terminating
on the docker bridge.
Thanks for any insights.
BR,
Sean.
__________________________________
Sean Murphy
Senior Platform Engineer
sean.mur...@datahouse.ch
T +41 44 289-84-22
www.datahouse.ch
Linkedin:
https://www.linkedin.com/company/wuestpartner/posts/?feedView=all&viewAsMember=true
YouTube: https://www.youtube.com/channel/UC4Esiu5N_zg2JRERufw5HvA
__________________________________
________________________________________
From: Winston Sorfleet <w...@romanus.ca>
Sent: Wednesday, March 19, 2025 7:16 PM
To: shorewall-users@lists.sourceforge.net
<shorewall-users@lists.sourceforge.net>
Subject: Re: [Shorewall-users] Problems accessing host from docker container
running on host
[You don't often get email from w...@romanus.ca. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
Normally I'd start with tcpdump as the lowest-level tracing tool, but
first I'd want to know a bit more about your scenario. Instead of using
"host" and "docker" terminology (I am not familiar with docker, so I am
not sure if you are implying a VM trying to communicate with the
underlying host), could you perhaps re-frame your question with "client"
and "server" and explain which are in which zones (and networks)? Or
are the client and server on the same host?
On 2025-03-19 05:49, Sean Murphy via Shorewall-users wrote:
Hi all,,
We have been (ab)using shorewall for some years now and we're v happy with it -
thanks everyone and Tom in particular for such a great tool.
We have been using it to manage security for a set of VMs running applications
with docker-compose. Almost all of our hosts have a single external network
interface; this is perhaps not the use case for which shorewall was designed
but it has been working for us so far.
We now have a scenario which is proving more difficult: we want to access a
service running on a host from within a container.
We have tried the most open configuration possible - a policy with all:all
ACCEPT and no rules; it seems the service is accessible from anywhere except
inside the docker container.
Accessing the service from inside the container results in timeouts, so
presumably
the packets are being dropped somewhere. We tried ping, ssh (on standard ports)
and an http service running on a high port number.
Zone configuration:
root@dhit-disposable01:/etc/shorewall# cat zones
###############################################################################
#ZONE TYPE OPTIONS IN OUT
# OPTIONS
OPTIONS
fw firewall
net ipv4
dock ipv4
Interface configuration:
root@dhit-disposable01:/etc/shorewall# cat interfaces
###############################################################################
?FORMAT 2
###############################################################################
#ZONE INTERFACE OPTIONS
net eth physical=eth+,dhcp,nosmurfs
net en physical=en+,dhcp,nosmurfs
dock docker0 physical=docker+,routeback=1
dock br physical=br-+,routeback=1
Policy configuration:
root@dhit-disposable01:/etc/shorewall# cat policy
#SOURCE DEST POLICY LOGLEVEL LIMIT
all all ACCEPT
Rules configuration:
root@dhit-disposable01:/etc/shorewall# cat rules
#ACTION SOURCE DEST PROTO DPORT
# No rules
Docker configuration as per shorewall.conf
root@dhit-disposable01:/etc/shorewall# grep -i docker shorewall.conf
# Default shorewall config, except for DOCKER=Yes (and this comment).
DOCKER=Yes
DOCKER_BRIDGE=docker0
I did shorewall compile, safe-reload and then restarted the docker deamon but
the packets still seem to be being dropped. I tried iptables-tracer [1] to get
some
info on where they disappear and it seems packets are being dropped on the
return path.
I checked the documentation and could not find any answer in the FAQs. I
could not generate a shorewall dump as we are using journald rather than
syslog and it's unclear to me how such a dump can be generated in this case.
Happy to provide further information as required.
Any thoughts/pointers appreciated...
Best rgds,
Sean.
[1] https://github.com/x-way/iptables-tracer
__________________________________
Sean Murphy
Senior Platform Engineer
sean.mur...@datahouse.ch
T +41 44 289-84-22
www.datahouse.ch
Linkedin:
https://www.linkedin.com/company/wuestpartner/posts/?feedView=all&viewAsMember=true
YouTube: https://www.youtube.com/channel/UC4Esiu5N_zg2JRERufw5HvA
__________________________________
_______________________________________________
Shorewall-users mailing list
Shorewall-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/shorewall-users
_______________________________________________
Shorewall-users mailing list
Shorewall-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/shorewall-users
_______________________________________________
Shorewall-users mailing list
Shorewall-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/shorewall-users
_______________________________________________
Shorewall-users mailing list
Shorewall-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/shorewall-users
