Allowing outgoing DNS traffic (destination port 53, both TCP and UDP) to the root servers is BCP for some reasons. First, RFC 5011 assumes resolvers are able to fetch new trust ancors from the root servers for a certain time period in order to do key rollovers.
Second, Unbound shows some side effects if it cannot do trust anchor signaling (see RFC 8145) or fetch the current trust anchor, resulting in SERVFAILs for arbitrary requests a few minutes.
There is little security implication of allowing DNS traffic to the root servers: An attacker might abuse this for exfiltrating data via DNS queries, but is unable to infiltrate data unless he gains control over at least one root server instance. If there is no firewall ruleset in place which prohibits any other DNS traffic than to chosen DNS servers, this patch will not have security implications at all.
Fixes #12183
Cc: Michael Tremer michael.tremer@ipfire.org Suggested-by: Horace Michael horace.michael@gmx.com Signed-off-by: Peter Müller peter.mueller@ipfire.org --- config/rootfiles/core/137/filelists/files | 1 + src/initscripts/system/firewall | 16 ++++++++++++++-- 2 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/config/rootfiles/core/137/filelists/files b/config/rootfiles/core/137/filelists/files index ce4e51768..a02840d12 100644 --- a/config/rootfiles/core/137/filelists/files +++ b/config/rootfiles/core/137/filelists/files @@ -1,4 +1,5 @@ etc/system-release etc/issue +etc/rc.d/init.d/firewall srv/web/ipfire/cgi-bin/credits.cgi var/ipfire/langs diff --git a/src/initscripts/system/firewall b/src/initscripts/system/firewall index ec396c708..ff63a2ede 100644 --- a/src/initscripts/system/firewall +++ b/src/initscripts/system/firewall @@ -6,10 +6,11 @@ eval $(/usr/local/bin/readhash /var/ipfire/ppp/settings) eval $(/usr/local/bin/readhash /var/ipfire/ethernet/settings) eval $(/usr/local/bin/readhash /var/ipfire/optionsfw/settings) -IFACE=`/bin/cat /var/ipfire/red/iface 2> /dev/null | /usr/bin/tr -d '\012'` +ROOTHINTS="/etc/unbound/root.hints" +IFACE=$( /bin/cat /var/ipfire/red/iface 2> /dev/null | /usr/bin/tr -d '\012' )
if [ -f /var/ipfire/red/device ]; then - DEVICE=`/bin/cat /var/ipfire/red/device 2> /dev/null | /usr/bin/tr -d '\012'` + DEVICE=$( /bin/cat /var/ipfire/red/device 2> /dev/null | /usr/bin/tr -d '\012' ) fi
function iptables() { @@ -307,6 +308,17 @@ iptables_init() { iptables -A INPUT -j TOR_INPUT iptables -N TOR_OUTPUT iptables -A OUTPUT -j TOR_OUTPUT + + # Allow outgoing DNS traffic (TCP and UDP) to DNS root servers + ROOTSERVERIPS="$( awk '/\s+A\s+/ { print $4 }' ${ROOTHINTS} | xargs )" + ipset -N root-servers iphash + + for ip in ${ROOTSERVERIPS}; do + ipset add root-servers $ip + done + + iptables -A OUTPUT -m set --match-set root-servers dst -p tcp --dport 53 -j ACCEPT + iptables -A OUTPUT -m set --match-set root-servers dst -p udp --dport 53 -j ACCEPT # Jump into the actual firewall ruleset. iptables -N INPUTFW
Hi,
On 25 Sep 2019, at 20:45, peter.mueller@ipfire.org wrote:
Allowing outgoing DNS traffic (destination port 53, both TCP and UDP) to the root servers is BCP for some reasons. First, RFC 5011 assumes resolvers are able to fetch new trust ancors from the root servers for a certain time period in order to do key rollovers.
Second, Unbound shows some side effects if it cannot do trust anchor signaling (see RFC 8145) or fetch the current trust anchor, resulting in SERVFAILs for arbitrary requests a few minutes.
There is little security implication of allowing DNS traffic to the root servers: An attacker might abuse this for exfiltrating data via DNS queries, but is unable to infiltrate data unless he gains control over at least one root server instance. If there is no firewall ruleset in place which prohibits any other DNS traffic than to chosen DNS servers, this patch will not have security implications at all.
I think we need to document this on the wiki before we merge this patch.
Fixes #12183
Cc: Michael Tremer michael.tremer@ipfire.org Suggested-by: Horace Michael horace.michael@gmx.com Signed-off-by: Peter Müller peter.mueller@ipfire.org
config/rootfiles/core/137/filelists/files | 1 + src/initscripts/system/firewall | 16 ++++++++++++++-- 2 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/config/rootfiles/core/137/filelists/files b/config/rootfiles/core/137/filelists/files index ce4e51768..a02840d12 100644 --- a/config/rootfiles/core/137/filelists/files +++ b/config/rootfiles/core/137/filelists/files @@ -1,4 +1,5 @@ etc/system-release etc/issue +etc/rc.d/init.d/firewall srv/web/ipfire/cgi-bin/credits.cgi var/ipfire/langs diff --git a/src/initscripts/system/firewall b/src/initscripts/system/firewall index ec396c708..ff63a2ede 100644 --- a/src/initscripts/system/firewall +++ b/src/initscripts/system/firewall @@ -6,10 +6,11 @@ eval $(/usr/local/bin/readhash /var/ipfire/ppp/settings) eval $(/usr/local/bin/readhash /var/ipfire/ethernet/settings) eval $(/usr/local/bin/readhash /var/ipfire/optionsfw/settings) -IFACE=`/bin/cat /var/ipfire/red/iface 2> /dev/null | /usr/bin/tr -d '\012'` +ROOTHINTS="/etc/unbound/root.hints" +IFACE=$( /bin/cat /var/ipfire/red/iface 2> /dev/null | /usr/bin/tr -d '\012' )
if [ -f /var/ipfire/red/device ]; then
- DEVICE=`/bin/cat /var/ipfire/red/device 2> /dev/null | /usr/bin/tr -d '\012'`
- DEVICE=$( /bin/cat /var/ipfire/red/device 2> /dev/null | /usr/bin/tr -d '\012' )
fi
Why the added whitespace? Should have been an extra patch.
function iptables() { @@ -307,6 +308,17 @@ iptables_init() { iptables -A INPUT -j TOR_INPUT iptables -N TOR_OUTPUT iptables -A OUTPUT -j TOR_OUTPUT
- # Allow outgoing DNS traffic (TCP and UDP) to DNS root servers
- ROOTSERVERIPS="$( awk '/\s+A\s+/ { print $4 }' ${ROOTHINTS} | xargs )"
- ipset -N root-servers iphash
ROOTSERVERIPS could have been an array and could have been local.
You do not need to call xargs. It is a rather expensive way to remove line breaks.
- for ip in ${ROOTSERVERIPS}; do
ipset add root-servers $ip- done
It is also interesting that ipset does not allow to add more IP addresses in one go. This looks like a very expensive loop for a lot of IP addresses. I think this is fine here for about a dozen addresses, but importing a blacklist of thousands or tens of thousands of IP addresses will take a long time.
iptables -A OUTPUT -m set --match-set root-servers dst -p tcp --dport 53 -j ACCEPT
iptables -A OUTPUT -m set --match-set root-servers dst -p udp --dport 53 -j ACCEPT
# Jump into the actual firewall ruleset. iptables -N INPUTFW
-- 2.16.4
-Michael
Hi all,
On Do, 2019-09-26 at 16:25 +0100, Michael Tremer wrote:
Hi,
On 25 Sep 2019, at 20:45, peter.mueller@ipfire.org wrote:
Allowing outgoing DNS traffic (destination port 53, both TCP and UDP) to the root servers is BCP for some reasons. First, RFC 5011 assumes resolvers are able to fetch new trust ancors from the root servers for a certain time period in order to do key rollovers.
Second, Unbound shows some side effects if it cannot do trust anchor signaling (see RFC 8145) or fetch the current trust anchor, resulting in SERVFAILs for arbitrary requests a few minutes.
There is little security implication of allowing DNS traffic to the root servers: An attacker might abuse this for exfiltrating data via DNS queries, but is unable to infiltrate data unless he gains control over at least one root server instance. If there is no firewall ruleset in place which prohibits any other DNS traffic than to chosen DNS servers, this patch will not have security implications at all.
I think we need to document this on the wiki before we merge this patch.
Fixes #12183
Cc: Michael Tremer michael.tremer@ipfire.org Suggested-by: Horace Michael horace.michael@gmx.com Signed-off-by: Peter Müller peter.mueller@ipfire.org
config/rootfiles/core/137/filelists/files | 1 + src/initscripts/system/firewall | 16 ++++++++++++++-- 2 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/config/rootfiles/core/137/filelists/files b/config/rootfiles/core/137/filelists/files index ce4e51768..a02840d12 100644 --- a/config/rootfiles/core/137/filelists/files +++ b/config/rootfiles/core/137/filelists/files @@ -1,4 +1,5 @@ etc/system-release etc/issue +etc/rc.d/init.d/firewall srv/web/ipfire/cgi-bin/credits.cgi var/ipfire/langs diff --git a/src/initscripts/system/firewall b/src/initscripts/system/firewall index ec396c708..ff63a2ede 100644 --- a/src/initscripts/system/firewall +++ b/src/initscripts/system/firewall @@ -6,10 +6,11 @@ eval $(/usr/local/bin/readhash /var/ipfire/ppp/settings) eval $(/usr/local/bin/readhash /var/ipfire/ethernet/settings) eval $(/usr/local/bin/readhash /var/ipfire/optionsfw/settings) -IFACE=`/bin/cat /var/ipfire/red/iface 2> /dev/null | /usr/bin/tr -d '\012'` +ROOTHINTS="/etc/unbound/root.hints" +IFACE=$( /bin/cat /var/ipfire/red/iface 2> /dev/null | /usr/bin/tr -d '\012' )
if [ -f /var/ipfire/red/device ]; then
- DEVICE=`/bin/cat /var/ipfire/red/device 2> /dev/null |
/usr/bin/tr -d '\012'`
- DEVICE=$( /bin/cat /var/ipfire/red/device 2> /dev/null |
/usr/bin/tr -d '\012' ) fi
Why the added whitespace? Should have been an extra patch.
function iptables() { @@ -307,6 +308,17 @@ iptables_init() { iptables -A INPUT -j TOR_INPUT iptables -N TOR_OUTPUT iptables -A OUTPUT -j TOR_OUTPUT
- # Allow outgoing DNS traffic (TCP and UDP) to DNS root servers
- ROOTSERVERIPS="$( awk '/\s+A\s+/ { print $4 }' ${ROOTHINTS} |
xargs )"
- ipset -N root-servers iphash
ROOTSERVERIPS could have been an array and could have been local.
You do not need to call xargs. It is a rather expensive way to remove line breaks.
- for ip in ${ROOTSERVERIPS}; do
ipset add root-servers $ip- done
It is also interesting that ipset does not allow to add more IP addresses in one go. This looks like a very expensive loop for a lot of IP addresses. I think this is fine here for about a dozen addresses, but importing a blacklist of thousands or tens of thousands of IP addresses will take a long time.
there is the possiblity to speed this process significantly up via 'ipset restore' whereby the format from 'ipset save' can be used which looks like this (if no counters has been set) -->
... add ipset_setname 11.22.33.44 -exist add ipset_setname 22.33.44.55 -exist ...
so if there is a vast list you can convert it e.g. via perl and pipe it to 'ipset restore'.
Example: IP list called 'vast_list' is formatted one per line
... 11.22.33.44 22.33.44.55 ...
can be formatted and restored with a
perl -pe 'chomp; $_ = "add ipset_setname $_ -exist\n"' vast_list | ipset restore
Just as a little gimmick :-).
- iptables -A OUTPUT -m set --match-set root-servers dst -p tcp
--dport 53 -j ACCEPT
- iptables -A OUTPUT -m set --match-set root-servers dst -p udp
--dport 53 -j ACCEPT
# Jump into the actual firewall ruleset. iptables -N INPUTFW -- 2.16.4
-Michael
Best,
Erik
Hi,
On 26 Sep 2019, at 20:17, ummeegge ummeegge@ipfire.org wrote:
Hi all,
On Do, 2019-09-26 at 16:25 +0100, Michael Tremer wrote:
Hi,
On 25 Sep 2019, at 20:45, peter.mueller@ipfire.org wrote:
Allowing outgoing DNS traffic (destination port 53, both TCP and UDP) to the root servers is BCP for some reasons. First, RFC 5011 assumes resolvers are able to fetch new trust ancors from the root servers for a certain time period in order to do key rollovers.
Second, Unbound shows some side effects if it cannot do trust anchor signaling (see RFC 8145) or fetch the current trust anchor, resulting in SERVFAILs for arbitrary requests a few minutes.
There is little security implication of allowing DNS traffic to the root servers: An attacker might abuse this for exfiltrating data via DNS queries, but is unable to infiltrate data unless he gains control over at least one root server instance. If there is no firewall ruleset in place which prohibits any other DNS traffic than to chosen DNS servers, this patch will not have security implications at all.
I think we need to document this on the wiki before we merge this patch.
Fixes #12183
Cc: Michael Tremer michael.tremer@ipfire.org Suggested-by: Horace Michael horace.michael@gmx.com Signed-off-by: Peter Müller peter.mueller@ipfire.org
config/rootfiles/core/137/filelists/files | 1 + src/initscripts/system/firewall | 16 ++++++++++++++-- 2 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/config/rootfiles/core/137/filelists/files b/config/rootfiles/core/137/filelists/files index ce4e51768..a02840d12 100644 --- a/config/rootfiles/core/137/filelists/files +++ b/config/rootfiles/core/137/filelists/files @@ -1,4 +1,5 @@ etc/system-release etc/issue +etc/rc.d/init.d/firewall srv/web/ipfire/cgi-bin/credits.cgi var/ipfire/langs diff --git a/src/initscripts/system/firewall b/src/initscripts/system/firewall index ec396c708..ff63a2ede 100644 --- a/src/initscripts/system/firewall +++ b/src/initscripts/system/firewall @@ -6,10 +6,11 @@ eval $(/usr/local/bin/readhash /var/ipfire/ppp/settings) eval $(/usr/local/bin/readhash /var/ipfire/ethernet/settings) eval $(/usr/local/bin/readhash /var/ipfire/optionsfw/settings) -IFACE=`/bin/cat /var/ipfire/red/iface 2> /dev/null | /usr/bin/tr -d '\012'` +ROOTHINTS="/etc/unbound/root.hints" +IFACE=$( /bin/cat /var/ipfire/red/iface 2> /dev/null | /usr/bin/tr -d '\012' )
if [ -f /var/ipfire/red/device ]; then
- DEVICE=`/bin/cat /var/ipfire/red/device 2> /dev/null |
/usr/bin/tr -d '\012'`
- DEVICE=$( /bin/cat /var/ipfire/red/device 2> /dev/null |
/usr/bin/tr -d '\012' ) fi
Why the added whitespace? Should have been an extra patch.
function iptables() { @@ -307,6 +308,17 @@ iptables_init() { iptables -A INPUT -j TOR_INPUT iptables -N TOR_OUTPUT iptables -A OUTPUT -j TOR_OUTPUT
- # Allow outgoing DNS traffic (TCP and UDP) to DNS root servers
- ROOTSERVERIPS="$( awk '/\s+A\s+/ { print $4 }' ${ROOTHINTS} |
xargs )"
- ipset -N root-servers iphash
ROOTSERVERIPS could have been an array and could have been local.
You do not need to call xargs. It is a rather expensive way to remove line breaks.
- for ip in ${ROOTSERVERIPS}; do
ipset add root-servers $ip- done
It is also interesting that ipset does not allow to add more IP addresses in one go. This looks like a very expensive loop for a lot of IP addresses. I think this is fine here for about a dozen addresses, but importing a blacklist of thousands or tens of thousands of IP addresses will take a long time.
there is the possiblity to speed this process significantly up via 'ipset restore' whereby the format from 'ipset save' can be used which looks like this (if no counters has been set) -->
... add ipset_setname 11.22.33.44 -exist add ipset_setname 22.33.44.55 -exist ...
so if there is a vast list you can convert it e.g. via perl and pipe it to 'ipset restore’.
Ah, that is what I was looking for.
Example: IP list called 'vast_list' is formatted one per line
... 11.22.33.44 22.33.44.55 ...
can be formatted and restored with a
perl -pe 'chomp; $_ = "add ipset_setname $_ -exist\n"' vast_list | ipset restore
Just as a little gimmick :-).
You can also do this without perl:
xargs printf — “add ipset_setname %s -exist\n” | ipset restore
It is quite expensive to launch the perl interpreter and this solution should be a little bit more lightweight. It has become a little bit of a sport now to have minimal bash snippets :)
Best, -Michael
- iptables -A OUTPUT -m set --match-set root-servers dst -p tcp
--dport 53 -j ACCEPT
- iptables -A OUTPUT -m set --match-set root-servers dst -p udp
--dport 53 -j ACCEPT
# Jump into the actual firewall ruleset. iptables -N INPUTFW -- 2.16.4
-Michael
Best,
Erik
Hello Michael, hello Erik,
thank you for your replies on this.
I think we need to document this on the wiki before we merge this patch.
Certainly, yes. I will do so if a patch covering this is merged.
Why the added whitespace? Should have been an extra patch.
All right. shellcheck complained here, and I thought this would be a low-hanging fruit. Shall I change something like this for multiple scripts in a patch?
Quality of our scripts in IPFire 2.x is quite poor at some points, and since we will have do deal with it for some time, I thought improving might be a good idea...
ROOTSERVERIPS could have been an array and could have been local.
Okay.
You do not need to call xargs. It is a rather expensive way to remove line breaks. Does this suit you:
local ROOTSERVERIPS="$( awk '/\s+A\s+/ { print $4 }' ${ROOTHINTS} )" [...] for ip in "${ROOTSERVERIPS[@]}"; do [...]
If yes, I will hand in a second patch. If not, please give me some suggestion. :-)
It is also interesting that ipset does not allow to add more IP addresses in one go. This looks like a very expensive loop for a lot of IP addresses. I think this is fine here for about a dozen addresses, but importing a blacklist of thousands or tens of thousands of IP addresses will take a long time.
there is the possiblity to speed this process significantly up via 'ipset restore' whereby the format from 'ipset save' can be used which looks like this (if no counters has been set) -->
... add ipset_setname 11.22.33.44 -exist add ipset_setname 22.33.44.55 -exist ...
so if there is a vast list you can convert it e.g. via perl and pipe it to 'ipset restore’.
Ah, that is what I was looking for.
Example: IP list called 'vast_list' is formatted one per line
... 11.22.33.44 22.33.44.55 ...
can be formatted and restored with a
perl -pe 'chomp; $_ = "add ipset_setname $_ -exist\n"' vast_list | ipset restore
Just as a little gimmick :-).
You can also do this without perl:
xargs printf — “add ipset_setname %s -exist\n” | ipset restore
It is quite expensive to launch the perl interpreter and this solution should be a little bit more lightweight. It has become a little bit of a sport now to have minimal bash snippets :)
Well, I consider processing 13 IP addresses not that problematic. How often does one a reboot, and how much extra time will ipset need here?
This simply is not a problem. Anyway, thank you for the hints - there still is an issue for processing some blacklists via firewall engine... :-)
Thanks, and best regards, Peter Müller
Hi Michael and Peter, just another beside one sorry for that...
On Mo, 2019-09-30 at 14:35 +0000, peter.mueller@ipfire.org wrote:
Hello Michael, hello Erik,
thank you for your replies on this.
I think we need to document this on the wiki before we merge this patch.
Certainly, yes. I will do so if a patch covering this is merged.
Why the added whitespace? Should have been an extra patch.
All right. shellcheck complained here, and I thought this would be a low-hanging fruit. Shall I change something like this for multiple scripts in a patch?
Quality of our scripts in IPFire 2.x is quite poor at some points, and since we will have do deal with it for some time, I thought improving might be a good idea...
ROOTSERVERIPS could have been an array and could have been local.
Okay.
You do not need to call xargs. It is a rather expensive way to remove line breaks. Does this suit you:
local ROOTSERVERIPS="$( awk '/\s+A\s+/ { print $4 }' ${ROOTHINTS} )" [...] for ip in "${ROOTSERVERIPS[@]}"; do [...]
If yes, I will hand in a second patch. If not, please give me some suggestion. :-)
It is also interesting that ipset does not allow to add more IP addresses in one go. This looks like a very expensive loop for a lot of IP addresses. I think this is fine here for about a dozen addresses, but importing a blacklist of thousands or tens of thousands of IP addresses will take a long time.
there is the possiblity to speed this process significantly up via 'ipset restore' whereby the format from 'ipset save' can be used which looks like this (if no counters has been set) -->
... add ipset_setname 11.22.33.44 -exist add ipset_setname 22.33.44.55 -exist ...
so if there is a vast list you can convert it e.g. via perl and pipe it to 'ipset restore’.
Ah, that is what I was looking for.
Example: IP list called 'vast_list' is formatted one per line
... 11.22.33.44 22.33.44.55 ...
can be formatted and restored with a
perl -pe 'chomp; $_ = "add ipset_setname $_ -exist\n"' vast_list | ipset restore
Just as a little gimmick :-).
You can also do this without perl:
xargs printf — “add ipset_setname %s -exist\n” | ipset restore
It is quite expensive to launch the perl interpreter and this solution should be a little bit more lightweight. It has become a little bit of a sport now to have minimal bash snippets :)
Did a fast test with awk, sed and Perl which looks like this:
+ perl -pe 'chomp; $_ = "add ipset_setname $_ -exist\n"' ip
real 0m0.071s user 0m0.060s sys 0m0.010s + sed -e 's/.*/add ipset_name & -exist/' ip
real 0m0.151s user 0m0.129s sys 0m0.012s + awk '{ print "add ipset_name "$0" -exist" }' ip
real 0m0.073s user 0m0.059s sys 0m0.014s + echo
++ wc -l ip + echo 'Number of IPs: 18985' Number of IPs: 18985 + exit 0
The printf command didn´t work.
Well, I consider processing 13 IP addresses not that problematic. How often does one a reboot, and how much extra time will ipset need here?
This simply is not a problem. Anyway, thank you for the hints - there still is an issue for processing some blacklists via firewall engine... :-)
Yes true, am handling some bigger lists at this time so it was a beneath info in general so to say ;-)
Thanks, and best regards, Peter Müller
Best,
Erik
Allowing outgoing DNS traffic (destination port 53, both TCP and UDP) to the root servers is BCP for some reasons. First, RFC 5011 assumes resolvers are able to fetch new trust ancors from the root servers for a certain time period in order to do key rollovers.
Second, Unbound shows some side effects if it cannot do trust anchor signaling (see RFC 8145) or fetch the current trust anchor, resulting in SERVFAILs for arbitrary requests a few minutes.
There is little security implication of allowing DNS traffic to the root servers: An attacker might abuse this for exfiltrating data via DNS queries, but is unable to infiltrate data unless he gains control over at least one root server instance. If there is no firewall ruleset in place which prohibits any other DNS traffic than to chosen DNS servers, this patch will not have security implications at all.
The second version of this patch does not use unnecessary xargs- call nor changes anything else not related to this issue.
Fixes #12183
Cc: Michael Tremer michael.tremer@ipfire.org Suggested-by: Horace Michael horace.michael@gmx.com Signed-off-by: Peter Müller peter.mueller@ipfire.org --- config/rootfiles/core/137/filelists/files | 1 + src/initscripts/system/firewall | 12 ++++++++++++ 2 files changed, 13 insertions(+)
diff --git a/config/rootfiles/core/137/filelists/files b/config/rootfiles/core/137/filelists/files index ce4e51768..a02840d12 100644 --- a/config/rootfiles/core/137/filelists/files +++ b/config/rootfiles/core/137/filelists/files @@ -1,4 +1,5 @@ etc/system-release etc/issue +etc/rc.d/init.d/firewall srv/web/ipfire/cgi-bin/credits.cgi var/ipfire/langs diff --git a/src/initscripts/system/firewall b/src/initscripts/system/firewall index ec396c708..602bd6c5b 100644 --- a/src/initscripts/system/firewall +++ b/src/initscripts/system/firewall @@ -6,6 +6,7 @@ eval $(/usr/local/bin/readhash /var/ipfire/ppp/settings) eval $(/usr/local/bin/readhash /var/ipfire/ethernet/settings) eval $(/usr/local/bin/readhash /var/ipfire/optionsfw/settings) +ROOTHINTS="/etc/unbound/root.hints" IFACE=`/bin/cat /var/ipfire/red/iface 2> /dev/null | /usr/bin/tr -d '\012'`
if [ -f /var/ipfire/red/device ]; then @@ -307,6 +308,17 @@ iptables_init() { iptables -A INPUT -j TOR_INPUT iptables -N TOR_OUTPUT iptables -A OUTPUT -j TOR_OUTPUT + + # Allow outgoing DNS traffic (TCP and UDP) to DNS root servers + local rootserverips="$( awk '/\s+A\s+/ { print $4 }' ${ROOTHINTS} )" + ipset -N root-servers iphash + + for ip in "${rootserverips[@]}"; do + ipset add root-servers $ip + done + + iptables -A OUTPUT -m set --match-set root-servers dst -p tcp --dport 53 -j ACCEPT + iptables -A OUTPUT -m set --match-set root-servers dst -p udp --dport 53 -j ACCEPT # Jump into the actual firewall ruleset. iptables -N INPUTFW
Acked-by: Michael Tremer michael.tremer@ipfire.org
On 1 Oct 2019, at 16:22, peter.mueller@ipfire.org wrote:
Allowing outgoing DNS traffic (destination port 53, both TCP and UDP) to the root servers is BCP for some reasons. First, RFC 5011 assumes resolvers are able to fetch new trust ancors from the root servers for a certain time period in order to do key rollovers.
Second, Unbound shows some side effects if it cannot do trust anchor signaling (see RFC 8145) or fetch the current trust anchor, resulting in SERVFAILs for arbitrary requests a few minutes.
There is little security implication of allowing DNS traffic to the root servers: An attacker might abuse this for exfiltrating data via DNS queries, but is unable to infiltrate data unless he gains control over at least one root server instance. If there is no firewall ruleset in place which prohibits any other DNS traffic than to chosen DNS servers, this patch will not have security implications at all.
The second version of this patch does not use unnecessary xargs- call nor changes anything else not related to this issue.
Fixes #12183
Cc: Michael Tremer michael.tremer@ipfire.org Suggested-by: Horace Michael horace.michael@gmx.com Signed-off-by: Peter Müller peter.mueller@ipfire.org
config/rootfiles/core/137/filelists/files | 1 + src/initscripts/system/firewall | 12 ++++++++++++ 2 files changed, 13 insertions(+)
diff --git a/config/rootfiles/core/137/filelists/files b/config/rootfiles/core/137/filelists/files index ce4e51768..a02840d12 100644 --- a/config/rootfiles/core/137/filelists/files +++ b/config/rootfiles/core/137/filelists/files @@ -1,4 +1,5 @@ etc/system-release etc/issue +etc/rc.d/init.d/firewall srv/web/ipfire/cgi-bin/credits.cgi var/ipfire/langs diff --git a/src/initscripts/system/firewall b/src/initscripts/system/firewall index ec396c708..602bd6c5b 100644 --- a/src/initscripts/system/firewall +++ b/src/initscripts/system/firewall @@ -6,6 +6,7 @@ eval $(/usr/local/bin/readhash /var/ipfire/ppp/settings) eval $(/usr/local/bin/readhash /var/ipfire/ethernet/settings) eval $(/usr/local/bin/readhash /var/ipfire/optionsfw/settings) +ROOTHINTS="/etc/unbound/root.hints" IFACE=`/bin/cat /var/ipfire/red/iface 2> /dev/null | /usr/bin/tr -d '\012'`
if [ -f /var/ipfire/red/device ]; then @@ -307,6 +308,17 @@ iptables_init() { iptables -A INPUT -j TOR_INPUT iptables -N TOR_OUTPUT iptables -A OUTPUT -j TOR_OUTPUT
# Allow outgoing DNS traffic (TCP and UDP) to DNS root servers
local rootserverips="$( awk '/\s+A\s+/ { print $4 }' ${ROOTHINTS} )"
ipset -N root-servers iphash
for ip in "${rootserverips[@]}"; do
ipset add root-servers $ipdone
iptables -A OUTPUT -m set --match-set root-servers dst -p tcp --dport 53 -j ACCEPT
iptables -A OUTPUT -m set --match-set root-servers dst -p udp --dport 53 -j ACCEPT
# Jump into the actual firewall ruleset. iptables -N INPUTFW
-- 2.16.4
this Code will not work:
- for ip in "${rootserverips[@]}"; do
ipset add root-servers $ip- done
it call ipset add ip1 ip2 ip3 ... because the doublequotes.
And if i fix this /etc/init.d/firewall restart complains because the ipset was not cleaned up before!
Arne
Am 2019-10-01 17:22, schrieb peter.mueller@ipfire.org:
Allowing outgoing DNS traffic (destination port 53, both TCP and UDP) to the root servers is BCP for some reasons. First, RFC 5011 assumes resolvers are able to fetch new trust ancors from the root servers for a certain time period in order to do key rollovers.
Second, Unbound shows some side effects if it cannot do trust anchor signaling (see RFC 8145) or fetch the current trust anchor, resulting in SERVFAILs for arbitrary requests a few minutes.
There is little security implication of allowing DNS traffic to the root servers: An attacker might abuse this for exfiltrating data via DNS queries, but is unable to infiltrate data unless he gains control over at least one root server instance. If there is no firewall ruleset in place which prohibits any other DNS traffic than to chosen DNS servers, this patch will not have security implications at all.
The second version of this patch does not use unnecessary xargs- call nor changes anything else not related to this issue.
Fixes #12183
Cc: Michael Tremer michael.tremer@ipfire.org Suggested-by: Horace Michael horace.michael@gmx.com Signed-off-by: Peter Müller peter.mueller@ipfire.org
config/rootfiles/core/137/filelists/files | 1 + src/initscripts/system/firewall | 12 ++++++++++++ 2 files changed, 13 insertions(+)
diff --git a/config/rootfiles/core/137/filelists/files b/config/rootfiles/core/137/filelists/files index ce4e51768..a02840d12 100644 --- a/config/rootfiles/core/137/filelists/files +++ b/config/rootfiles/core/137/filelists/files @@ -1,4 +1,5 @@ etc/system-release etc/issue +etc/rc.d/init.d/firewall srv/web/ipfire/cgi-bin/credits.cgi var/ipfire/langs diff --git a/src/initscripts/system/firewall b/src/initscripts/system/firewall index ec396c708..602bd6c5b 100644 --- a/src/initscripts/system/firewall +++ b/src/initscripts/system/firewall @@ -6,6 +6,7 @@ eval $(/usr/local/bin/readhash /var/ipfire/ppp/settings) eval $(/usr/local/bin/readhash /var/ipfire/ethernet/settings) eval $(/usr/local/bin/readhash /var/ipfire/optionsfw/settings) +ROOTHINTS="/etc/unbound/root.hints" IFACE=`/bin/cat /var/ipfire/red/iface 2> /dev/null | /usr/bin/tr -d '\012'`
if [ -f /var/ipfire/red/device ]; then @@ -307,6 +308,17 @@ iptables_init() { iptables -A INPUT -j TOR_INPUT iptables -N TOR_OUTPUT iptables -A OUTPUT -j TOR_OUTPUT
- # Allow outgoing DNS traffic (TCP and UDP) to DNS root servers
- local rootserverips="$( awk '/\s+A\s+/ { print $4 }' ${ROOTHINTS} )"
- ipset -N root-servers iphash
- for ip in "${rootserverips[@]}"; do
ipset add root-servers $ip- done
- iptables -A OUTPUT -m set --match-set root-servers dst -p tcp
--dport 53 -j ACCEPT
- iptables -A OUTPUT -m set --match-set root-servers dst -p udp
--dport 53 -j ACCEPT
# Jump into the actual firewall ruleset. iptables -N INPUTFW
I have also found another problem. This patch is useless because you need the rootserver only in recursor mode but in recursor mode you need access to all dns servers of the domain ownwers.
So allowing only the rootservers is useless because you still cannot resolve domains.
Arne
Am 2019-10-18 09:08, schrieb Arne Fitzenreiter:
this Code will not work:
- for ip in "${rootserverips[@]}"; do
ipset add root-servers $ip- done
it call ipset add ip1 ip2 ip3 ... because the doublequotes.
And if i fix this /etc/init.d/firewall restart complains because the ipset was not cleaned up before!
Arne
Am 2019-10-01 17:22, schrieb peter.mueller@ipfire.org:
Allowing outgoing DNS traffic (destination port 53, both TCP and UDP) to the root servers is BCP for some reasons. First, RFC 5011 assumes resolvers are able to fetch new trust ancors from the root servers for a certain time period in order to do key rollovers.
Second, Unbound shows some side effects if it cannot do trust anchor signaling (see RFC 8145) or fetch the current trust anchor, resulting in SERVFAILs for arbitrary requests a few minutes.
There is little security implication of allowing DNS traffic to the root servers: An attacker might abuse this for exfiltrating data via DNS queries, but is unable to infiltrate data unless he gains control over at least one root server instance. If there is no firewall ruleset in place which prohibits any other DNS traffic than to chosen DNS servers, this patch will not have security implications at all.
The second version of this patch does not use unnecessary xargs- call nor changes anything else not related to this issue.
Fixes #12183
Cc: Michael Tremer michael.tremer@ipfire.org Suggested-by: Horace Michael horace.michael@gmx.com Signed-off-by: Peter Müller peter.mueller@ipfire.org
config/rootfiles/core/137/filelists/files | 1 + src/initscripts/system/firewall | 12 ++++++++++++ 2 files changed, 13 insertions(+)
diff --git a/config/rootfiles/core/137/filelists/files b/config/rootfiles/core/137/filelists/files index ce4e51768..a02840d12 100644 --- a/config/rootfiles/core/137/filelists/files +++ b/config/rootfiles/core/137/filelists/files @@ -1,4 +1,5 @@ etc/system-release etc/issue +etc/rc.d/init.d/firewall srv/web/ipfire/cgi-bin/credits.cgi var/ipfire/langs diff --git a/src/initscripts/system/firewall b/src/initscripts/system/firewall index ec396c708..602bd6c5b 100644 --- a/src/initscripts/system/firewall +++ b/src/initscripts/system/firewall @@ -6,6 +6,7 @@ eval $(/usr/local/bin/readhash /var/ipfire/ppp/settings) eval $(/usr/local/bin/readhash /var/ipfire/ethernet/settings) eval $(/usr/local/bin/readhash /var/ipfire/optionsfw/settings) +ROOTHINTS="/etc/unbound/root.hints" IFACE=`/bin/cat /var/ipfire/red/iface 2> /dev/null | /usr/bin/tr -d '\012'`
if [ -f /var/ipfire/red/device ]; then @@ -307,6 +308,17 @@ iptables_init() { iptables -A INPUT -j TOR_INPUT iptables -N TOR_OUTPUT iptables -A OUTPUT -j TOR_OUTPUT
- # Allow outgoing DNS traffic (TCP and UDP) to DNS root servers
- local rootserverips="$( awk '/\s+A\s+/ { print $4 }' ${ROOTHINTS} )"
- ipset -N root-servers iphash
- for ip in "${rootserverips[@]}"; do
ipset add root-servers $ip- done
- iptables -A OUTPUT -m set --match-set root-servers dst -p tcp
--dport 53 -j ACCEPT
- iptables -A OUTPUT -m set --match-set root-servers dst -p udp
--dport 53 -j ACCEPT
# Jump into the actual firewall ruleset. iptables -N INPUTFW
-
Arne Fitzenreiter -
Michael Tremer -
peter.mueller＠ipfire.org -
ummeegge