Hello,
for quite some time, IPFire includes Tor via Pakfire as an add-on.
Trying to set up a Tor relay there, I stumbled into several problems regarding firewall rule configuration:
(a) Inbound It turns out that Tor is not working correctly if GeoIP block is active (this occurred after a reboot - strange). Of course, one possibility is to disable GeoIP block at all, allow access to the Tor relay ports, and deny any except those of legitimate countries to other services on the firewall machine.
Since this enlarges the ruleset (already quite complex here :-| ), I am wondering if there is a more simple way to achieve this.
(b) Outbound For security reasons (surprise!), outgoing connections are heavily limited here - only DNS, NTP and web traffic is allowed, and only to a certain list of countries. Some call that "racist routing"...
This does not work with Tor since it needs to open connections to almost any port on almost any IP address. Allowing outbound traffic in general is out of question, so there seems to possibility left.
Besides from running a Tor relay in the local DMZ and apply the firewall rules for this machine, is there another way?
Thanks, and best regards, Peter Müller
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512
Hello,
On Wed, 2018-06-27 at 22:53 +0200, Peter Müller wrote:
Hello,
for quite some time, IPFire includes Tor via Pakfire as an add-on.
Trying to set up a Tor relay there, I stumbled into several problems regarding firewall rule configuration:
(a) Inbound It turns out that Tor is not working correctly if GeoIP block is active (this occurred after a reboot - strange). Of course, one possibility is to disable GeoIP block at all, allow access to the Tor relay ports, and deny any except those of legitimate countries to other services on the firewall machine.
You can use the normal firewall rules for a more granular configuration.
The geoip filter comes first and then all the rest. Depending on how many countries you block here, Tor connectivity becomes a little bit useless.
Since this enlarges the ruleset (already quite complex here :-| ), I am wondering if there is a more simple way to achieve this.
We could move tor rules before the GeoIP filter, but I am not sure if that is very intuitive.
(b) Outbound For security reasons (surprise!), outgoing connections are heavily limited here - only DNS, NTP and web traffic is allowed, and only to a certain list of countries. Some call that "racist routing"...
This does not work with Tor since it needs to open connections to almost any port on almost any IP address. Allowing outbound traffic in general is out of question, so there seems to possibility left.
Besides from running a Tor relay in the local DMZ and apply the firewall rules for this machine, is there another way?
Not that I am aware of.
You can build something custom here by using the -m owner module of iptables and make an exception in the OUTPUT chain for the tor process. You just need a little script that puts the pid into it if you cannot check by uid.
Best, - -Michael
Thanks, and best regards, Peter Müller
Hello Michael,
thanks for the clarification.
Hello,
On Wed, 2018-06-27 at 22:53 +0200, Peter Müller wrote:
Hello,
for quite some time, IPFire includes Tor via Pakfire as an add-on.
Trying to set up a Tor relay there, I stumbled into several problems regarding firewall rule configuration:
(a) Inbound It turns out that Tor is not working correctly if GeoIP block is active (this occurred after a reboot - strange). Of course, one possibility is to disable GeoIP block at all, allow access to the Tor relay ports, and deny any except those of legitimate countries to other services on the firewall machine.
You can use the normal firewall rules for a more granular configuration.
The geoip filter comes first and then all the rest. Depending on how many countries you block here, Tor connectivity becomes a little bit useless.
Indeed. And I block many... :-)
Since this enlarges the ruleset (already quite complex here :-| ), I am wondering if there is a more simple way to achieve this.
We could move tor rules before the GeoIP filter, but I am not sure if that is very intuitive.
I do not think so since users may expect anything is blocked then and wonder why Tor still works fine. We should keep firewall things intentional in order not to puzzle users.
OK, incoming way is solved then.
(b) Outbound For security reasons (surprise!), outgoing connections are heavily limited here - only DNS, NTP and web traffic is allowed, and only to a certain list of countries. Some call that "racist routing"...
This does not work with Tor since it needs to open connections to almost any port on almost any IP address. Allowing outbound traffic in general is out of question, so there seems to possibility left.
Besides from running a Tor relay in the local DMZ and apply the firewall rules for this machine, is there another way?
Not that I am aware of.
You can build something custom here by using the -m owner module of iptables and make an exception in the OUTPUT chain for the tor process. You just need a little script that puts the pid into it if you cannot check by uid.
Hm, I never used the "owner" module before...
I guess these custom firewall will need to be placed in "firewall.local" (https://wiki.ipfire.org/configuration/firewall/firewall.local)? According to the firewall processing scheme (https://wiki.ipfire.org/_media/configuration/firewall/ipfire_fw_chains.jpg), it is processed before anything else, so this would suit.
Will test this and get back if problems occur.
Best regards, Peter Müller
Hello,
while incoming firewall rules seem to work by now, there are still some issues with outgoing traffic:
(a) Since tor runs as "nobody" (why?), allowing traffic from this user is out of questions because also untrusted services like Apache occupy this user. (b) Filtering by PID seems the only way, but creates error messages:
iptables v1.4.21: unknown option "--pid-owner" Try `iptables -h' or 'iptables --help' for more information.
In firewall.local, this rule is currently placed:
iptables -A CUSTOMOUTPUT -o ppp0 -m owner --pid-owner $TORPID -p tcp -d 0.0.0.0/0 -j ACCEPT
Besides from making things more easy in the future (development ;-) ), is "--pid-owner" even supported by iptables running here? Or does it require some special module?
Best regards, Peter Müller
Am 28.06.2018 um 19:14 schrieb Peter Müller:
Hello Michael,
thanks for the clarification.
Hello,
On Wed, 2018-06-27 at 22:53 +0200, Peter Müller wrote:
Hello,
for quite some time, IPFire includes Tor via Pakfire as an add-on.
Trying to set up a Tor relay there, I stumbled into several problems regarding firewall rule configuration:
(a) Inbound It turns out that Tor is not working correctly if GeoIP block is active (this occurred after a reboot - strange). Of course, one possibility is to disable GeoIP block at all, allow access to the Tor relay ports, and deny any except those of legitimate countries to other services on the firewall machine.
You can use the normal firewall rules for a more granular configuration.
The geoip filter comes first and then all the rest. Depending on how many countries you block here, Tor connectivity becomes a little bit useless.
Indeed. And I block many... :-)
Since this enlarges the ruleset (already quite complex here :-| ), I am wondering if there is a more simple way to achieve this.
We could move tor rules before the GeoIP filter, but I am not sure if that is very intuitive.
I do not think so since users may expect anything is blocked then and wonder why Tor still works fine. We should keep firewall things intentional in order not to puzzle users.
OK, incoming way is solved then.
(b) Outbound For security reasons (surprise!), outgoing connections are heavily limited here - only DNS, NTP and web traffic is allowed, and only to a certain list of countries. Some call that "racist routing"...
This does not work with Tor since it needs to open connections to almost any port on almost any IP address. Allowing outbound traffic in general is out of question, so there seems to possibility left.
Besides from running a Tor relay in the local DMZ and apply the firewall rules for this machine, is there another way?
Not that I am aware of.
You can build something custom here by using the -m owner module of iptables and make an exception in the OUTPUT chain for the tor process. You just need a little script that puts the pid into it if you cannot check by uid.
Hm, I never used the "owner" module before...
I guess these custom firewall will need to be placed in "firewall.local" (https://wiki.ipfire.org/configuration/firewall/firewall.local)? According to the firewall processing scheme (https://wiki.ipfire.org/_media/configuration/firewall/ipfire_fw_chains.jpg), it is processed before anything else, so this would suit.
Will test this and get back if problems occur.
Best regards, Peter Müller
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512
On Fri, 2018-06-29 at 23:26 +0200, Peter Müller wrote:
Hello,
while incoming firewall rules seem to work by now, there are still some issues with outgoing traffic:
(a) Since tor runs as "nobody" (why?), allowing traffic from this user is out of questions because also untrusted services like Apache occupy this user.
Everything that is non-privileged runs as this. In IPFire 3 everything has its own user.
(b) Filtering by PID seems the only way, but creates error messages:
iptables v1.4.21: unknown option "--pid-owner" Try `iptables -h' or 'iptables --help' for more information.
Did you try the updated iptables that you submitted this week?
In firewall.local, this rule is currently placed:
iptables -A CUSTOMOUTPUT -o ppp0 -m owner --pid-owner $TORPID -p tcp -d 0.0.0.0/0 -j ACCEPT
Besides from making things more easy in the future (development ;-) ), is "--pid-owner" even supported by iptables running here? Or does it require some special module?
Not that I am aware of.
- -Michael
Best regards, Peter Müller
Am 28.06.2018 um 19:14 schrieb Peter Müller:
Hello Michael,
thanks for the clarification.
Hello,
On Wed, 2018-06-27 at 22:53 +0200, Peter Müller wrote:
Hello, for quite some time, IPFire includes Tor via Pakfire as an add-on. Trying to set up a Tor relay there, I stumbled into several problems regarding firewall rule configuration: (a) Inbound It turns out that Tor is not working correctly if GeoIP block is active (this occurred after a reboot - strange). Of course, one possibility is to disable GeoIP block at all, allow access to the Tor relay ports, and deny any except those of legitimate countries to other services on the firewall machine.
You can use the normal firewall rules for a more granular configuration.
The geoip filter comes first and then all the rest. Depending on how many countries you block here, Tor connectivity becomes a little bit useless.
Indeed. And I block many... :-)
Since this enlarges the ruleset (already quite complex here :-| ), I am wondering if there is a more simple way to achieve this.
We could move tor rules before the GeoIP filter, but I am not sure if that is very intuitive.
I do not think so since users may expect anything is blocked then and wonder why Tor still works fine. We should keep firewall things intentional in order not to puzzle users.
OK, incoming way is solved then.
(b) Outbound For security reasons (surprise!), outgoing connections are heavily limited here - only DNS, NTP and web traffic is allowed, and only to a certain list of countries. Some call that "racist routing"... This does not work with Tor since it needs to open connections to almost any port on almost any IP address. Allowing outbound traffic in general is out of question, so there seems to possibility left. Besides from running a Tor relay in the local DMZ and apply the firewall rules for this machine, is there another way?
Not that I am aware of.
You can build something custom here by using the -m owner module of iptables and make an exception in the OUTPUT chain for the tor process. You just need a little script that puts the pid into it if you cannot check by uid.
Hm, I never used the "owner" module before...
I guess these custom firewall will need to be placed in "firewall.local" (https://wiki.ipfire.org/configuration/firewall/firewall.local)? According to the firewall processing scheme (https://wiki.ipfire.org/_media/configuration/firewall/ipfire_fw_chains.jpg) , it is processed before anything else, so this would suit.
Will test this and get back if problems occur.
Best regards, Peter Müller
Hello Michael,
On Fri, 2018-06-29 at 23:26 +0200, Peter Müller wrote:
Hello,
while incoming firewall rules seem to work by now, there are still some issues with outgoing traffic:
(a) Since tor runs as "nobody" (why?), allowing traffic from this user is out of questions because also untrusted services like Apache occupy this user.
Everything that is non-privileged runs as this. In IPFire 3 everything has its own user.
Is there a technical reason why we did not split this up into several users in 2.x as well? How much work would it be to change this for 2.x too?
(b) Filtering by PID seems the only way, but creates error messages:
iptables v1.4.21: unknown option "--pid-owner" Try `iptables -h' or 'iptables --help' for more information.
Did you try the updated iptables that you submitted this week?
Not yet. It might be possible that "--pid-owner" is implemented there, as it does not appear in the documentation for 1.4.x .
Either way, filtering by PID has some disadvantages: (a) Every time a process changes its PID, we need to reload firewall.local. (What do we do with forks anyway?) Since PIDs may not be unique on Linux systems, some other program could obtain these network privileges.
(b) The initscript of Tor needs to be patched in order to reload firewall.local . During boot sequence, things are loaded the other way round, so the PID cannot be determined. A dedicated user would help here a lot.
At the moment, running a relay on an ARM board in the local DMZ seems to be a more elegant way. However, on systems with any outbound connection allowed (which I _strongly_ advise against), this is not a pity since inbound connections can be handled even by using the WebUI.
Best regards, Peter Müller
In firewall.local, this rule is currently placed:
iptables -A CUSTOMOUTPUT -o ppp0 -m owner --pid-owner $TORPID -p tcp -d 0.0.0.0/0 -j ACCEPT
Besides from making things more easy in the future (development ;-) ), is "--pid-owner" even supported by iptables running here? Or does it require some special module?
Not that I am aware of.
-Michael
Best regards, Peter Müller
Am 28.06.2018 um 19:14 schrieb Peter Müller:
Hello Michael,
thanks for the clarification.
Hello,
On Wed, 2018-06-27 at 22:53 +0200, Peter Müller wrote:
Hello, for quite some time, IPFire includes Tor via Pakfire as an add-on. Trying to set up a Tor relay there, I stumbled into several problems regarding firewall rule configuration: (a) Inbound It turns out that Tor is not working correctly if GeoIP block is active (this occurred after a reboot - strange). Of course, one possibility is to disable GeoIP block at all, allow access to the Tor relay ports, and deny any except those of legitimate countries to other services on the firewall machine.
You can use the normal firewall rules for a more granular configuration.
The geoip filter comes first and then all the rest. Depending on how many countries you block here, Tor connectivity becomes a little bit useless.
Indeed. And I block many... :-)
Since this enlarges the ruleset (already quite complex here :-| ), I am wondering if there is a more simple way to achieve this.
We could move tor rules before the GeoIP filter, but I am not sure if that is very intuitive.
I do not think so since users may expect anything is blocked then and wonder why Tor still works fine. We should keep firewall things intentional in order not to puzzle users.
OK, incoming way is solved then.
(b) Outbound For security reasons (surprise!), outgoing connections are heavily limited here - only DNS, NTP and web traffic is allowed, and only to a certain list of countries. Some call that "racist routing"... This does not work with Tor since it needs to open connections to almost any port on almost any IP address. Allowing outbound traffic in general is out of question, so there seems to possibility left. Besides from running a Tor relay in the local DMZ and apply the firewall rules for this machine, is there another way?
Not that I am aware of.
You can build something custom here by using the -m owner module of iptables and make an exception in the OUTPUT chain for the tor process. You just need a little script that puts the pid into it if you cannot check by uid.
Hm, I never used the "owner" module before...
I guess these custom firewall will need to be placed in "firewall.local" (https://wiki.ipfire.org/configuration/firewall/firewall.local)? According to the firewall processing scheme (https://wiki.ipfire.org/_media/configuration/firewall/ipfire_fw_chains.jpg) , it is processed before anything else, so this would suit.
Will test this and get back if problems occur.
Best regards, Peter Müller
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512
On Sun, 2018-07-01 at 08:00 +0200, Peter Müller wrote:
Hello Michael,
On Fri, 2018-06-29 at 23:26 +0200, Peter Müller wrote:
Hello, while incoming firewall rules seem to work by now, there are still some issues with outgoing traffic: (a) Since tor runs as "nobody" (why?), allowing traffic from this user is out of questions because also untrusted services like Apache occupy this user.
Everything that is non-privileged runs as this. In IPFire 3 everything has its own user.
Is there a technical reason why we did not split this up into several users in 2.x as well? How much work would it be to change this for 2.x too?
Yes, useradd isn't very well configured and does (or did) not support system users and all this stuff. You can give it a try.
(b) Filtering by PID seems the only way, but creates error messages: iptables v1.4.21: unknown option "--pid-owner" Try `iptables -h' or 'iptables --help' for more information.
Did you try the updated iptables that you submitted this week?
Not yet. It might be possible that "--pid-owner" is implemented there, as it does not appear in the documentation for 1.4.x .
Either way, filtering by PID has some disadvantages: (a) Every time a process changes its PID, we need to reload firewall.local. (What do we do with forks anyway?) Since PIDs may not be unique on Linux systems, some other program could obtain these network privileges.
(b) The initscript of Tor needs to be patched in order to reload firewall.local . During boot sequence, things are loaded the other way round, so the PID cannot be determined. A dedicated user would help here a lot.
Agreed.
At the moment, running a relay on an ARM board in the local DMZ seems to be a more elegant way. However, on systems with any outbound connection allowed (which I _strongly_ advise against), this is not a pity since inbound connections can be handled even by using the WebUI.
Best regards, Peter Müller
In firewall.local, this rule is currently placed: iptables -A CUSTOMOUTPUT -o ppp0 -m owner --pid-owner $TORPID -p tcp -d 0.0.0.0/0 -j ACCEPT Besides from making things more easy in the future (development ;-) ), is "--pid-owner" even supported by iptables running here? Or does it require some special module?
Not that I am aware of.
-Michael
Best regards, Peter Müller Am 28.06.2018 um 19:14 schrieb Peter Müller:
Hello Michael,
thanks for the clarification.
Hello,
On Wed, 2018-06-27 at 22:53 +0200, Peter Müller wrote:
Hello, for quite some time, IPFire includes Tor via Pakfire as an add-on. Trying to set up a Tor relay there, I stumbled into several problems regarding firewall rule configuration: (a) Inbound It turns out that Tor is not working correctly if GeoIP block is active (this occurred after a reboot - strange). Of course, one possibility is to disable GeoIP block at all, allow access to the Tor relay ports, and deny any except those of legitimate countries to other services on the firewall machine.
You can use the normal firewall rules for a more granular configuration.
The geoip filter comes first and then all the rest. Depending on how many countries you block here, Tor connectivity becomes a little bit useless.
Indeed. And I block many... :-)
Since this enlarges the ruleset (already quite complex here :-| ), I am wondering if there is a more simple way to achieve this.
We could move tor rules before the GeoIP filter, but I am not sure if that is very intuitive.
I do not think so since users may expect anything is blocked then and wonder why Tor still works fine. We should keep firewall things intentional in order not to puzzle users.
OK, incoming way is solved then.
(b) Outbound For security reasons (surprise!), outgoing connections are heavily limited here - only DNS, NTP and web traffic is allowed, and only to a certain list of countries. Some call that "racist routing"... This does not work with Tor since it needs to open connections to almost any port on almost any IP address. Allowing outbound traffic in general is out of question, so there seems to possibility left. Besides from running a Tor relay in the local DMZ and apply the firewall rules for this machine, is there another way?
Not that I am aware of.
You can build something custom here by using the -m owner module of iptables and make an exception in the OUTPUT chain for the tor process. You just need a little script that puts the pid into it if you cannot check by uid.
Hm, I never used the "owner" module before...
I guess these custom firewall will need to be placed in "firewall.local" (https://wiki.ipfire.org/configuration/firewall/firewall.local)? According to the firewall processing scheme (https://wiki.ipfire.org/_media/configuration/firewall/ipfire_fw_chains. jpg) , it is processed before anything else, so this would suit.
Will test this and get back if problems occur.
Best regards, Peter Müller
-
Michael Tremer -
Peter Müller