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Re: [Astlinux-users] Large number of Firewall entries
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From: Lonnie A. <li...@lo...> - 2023-01-02 22:07:31
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Hi Michael,
I rolled up my sleeves, and gave this a test in my lab:
-- snip /etc/arno-iptables-firewall/custom-rules --
ipset_ext_input_allow()
{
local proto="$1" port="$2" set="$3" file="$4"
if [ ! -f "$file" ]; then
echo "[CUSTOM RULE] ipset_ext_input_allow: File not found: $file"
return
fi
echo "[CUSTOM RULE] IPSet Pass EXT->Local for Proto: $proto, Port: $port, Set: $set, IPsetFile: $file"
ipset create -exist $set hash:net
ipset flush $set
sed -n -r -e "s/^([0-9][0-9./]+)([[:space:]].*|)$/add -exist ${set} \1/p" "$file" | ipset restore
ip4tables -A EXT_INPUT_CHAIN -m set --match-set $set src -p $proto --dport $port -j ACCEPT
}
ipset_ext_input_allow udp 5060 udp_sip_hosts /tmp/sip-whitelist.netset
--
-- /tmp/sip-whitelist.netset --
##
1.2.3.4 #test
#10.10.50.1
10.10.50.55
#10.10.0.0/16
--
It worked as expected. Restarting the firewall "arno-iptables-firewall restart" applies the current IPv4 .netset file.
> If I then remove the address and restart the firewall, the address is removed from the list (ipset list confirms this) but the address is still open in the firewall. I cannot remove it unless I reboot the system.
What you are seeing is the iptables conntrack state table, eventually the UDP state will expire after 120 seconds (unless traffic resets the state)
Source Port (#'s) Destination Port Protocol Packets Bytes TTL
10.10.50.1 5060 10.10.50.64 5060 UDP 24 13856 1:29
After the TTL counts down to 0 then the conntrack state disappears. The iptables conntrack state table makes the firewall much more efficient. This behavior has always existed.
So in your testing, if you wait 2 minutes after you remove an IP and apply the change, the IP will be blocked for UDP 5060 traffic.
If you are getting a constant stream of UDP 5060 traffic from that IP then you would need to take additional measures to block further traffic. For example, if you allowed a remote SIP endpoint to register more often than 120 seconds, removing the IP from the "allowed" ipset would not "block" it until the conntrack state disappears.
Make sense?
Lonnie
> On Jan 2, 2023, at 2:26 PM, Michael Knill <mic...@ip...> wrote:
>
> Hi Lonnie
>
> Thanks for this. Unfortunately I still need to reboot the system for it to reread the netset rules if I remove an ipset entry.
> Here is my custom-rules.conf:
> --------
> ipset create -exist udp_sip_hosts hash:net
> ipset flush udp_sip_hosts
> ipset add -exist udp_sip_hosts <my ip address added here>
> iptables -A EXT_INPUT_CHAIN -m set --match-set udp_sip_hosts src -p udp --dport 5060 -j ACCEPT
> --------
>
> If I add another IP Address to the list as below and restart the firewall it works fine and I see it when I do an ipset list:
> ipset add -exist udp_sip_hosts <1st ip address>
> ipset add -exist udp_sip_hosts <2nd ip address>
>
> If I then remove the address and restart the firewall, the address is removed from the list (ipset list confirms this) but the address is still open in the firewall. I cannot remove it unless I reboot the system.
> Obviously not workable I'm afraid.
>
> Regards
> Michael Knill
>
>
>
> On 3/1/2023, 3:22 am, "Lonnie Abelbeck" <li...@lo... <mailto:li...@lo...>> wrote:
>
>
> Hi Michael,
>
>
> Referring to the "apply_ipset_netset()" function (here [1])
>
>
> Add "-exist" to the "create" and "add" (man-page [2]) commands.
>
>
> Note that you can create the ipset from a text file within the /etc/arno-iptables-firewall/custom-rules script. Edit your text file and reload the firewall.
>
>
> Using "ipset create -exist ..." will not fail if the ipset already exists. "ipset flush ..." will clear any pre-existing ipset.
>
>
> Tip -> I would probably use "hash:net" instead of "hash:ip" so you could use CIDRs if you wanted.
>
>
> custom-rules script snippet
> --
> ipset create -exist udp_sip_hosts hash:net
> ipset flush udp_sip_hosts
>
>
> ## either a one-liner from a text file "sip-whitelist.netset"
> sed -n -r -e "s/^([0-9][0-9./]+)([[:space:]].*|)$/add -exist udp_sip_hosts \1/p" sip-whitelist.netset | ipset restore
>
>
> ## Or, loop getting IPv4s from a text file "sip-whitelist.netset"
> ipset add -exist udp_sip_hosts <IP Address>
> ## done-loop
>
>
> iptables -A EXT_INPUT_CHAIN -m set --match-set udp_sip_hosts src -p udp --dport 5060 -j ACCEPT
> --
>
>
> Lonnie
>
>
> [1] https://github.com/astlinux-project/astlinux/blob/d95ba9c3914b135da4440cb95f32af61a41d4650/package/arnofw/aif/bin/arno-iptables-firewall#L4275 <https://github.com/astlinux-project/astlinux/blob/d95ba9c3914b135da4440cb95f32af61a41d4650/package/arnofw/aif/bin/arno-iptables-firewall#L4275>
>
>
> [2] https://ipset.netfilter.org/ipset.man.html <https://ipset.netfilter.org/ipset.man.html>
>
>
>
>
>> On Jan 1, 2023, at 11:44 PM, Michael Knill <mic...@ip... <mailto:mic...@ip...>> wrote:
>>
>> Hi All
>> Merry Christmas and Happy New Year.
>>
>> Just rejuvenating this thread as I am building our new softswitch and playing with ipset as you offered below.
>> We have done the following:
>>
>> Using CLI:
>> ipset create udp_sip_hosts hash:ip
>> ipset add udp_sip_hosts <IP Address>
>>
>> In custom-rules.conf
>> iptables -A EXT_INPUT_CHAIN -m set --match-set udp_sip_hosts src -p udp --dport 5060 -j ACCEPT
>>
>> It all seems to work fine but I obviously am an iptables noob as I have no idea what to do when I make changes to the ipset as it does not change even after a firewall restart.
>> I'm sure there is something I need to do which will get iptables to reread the ipset?
>>
>> Thanks guys.
>>
>> Regards
>> Michael Knill
>>
>>
>>
>> On 27/9/2021, 10:54 am, "Lonnie Abelbeck" <li...@lo... <mailto:li...@lo...> <mailto:li...@lo... <mailto:li...@lo...>>> wrote:
>>
>>
>> Michael,
>>
>>
>> The /mnt/kd/arno-iptables-firewall/custom-rules is a basic shell script, so parsing sip.conf using 'sed' or such should be reasonably straightforward.
>>
>>
>> BTW, for extra credit, if you combined all the allowed SIP IPs into an ipset (ex. udp_sip_hosts), you can very efficiently match all of them with only one rule:
>> --
>> iptables -A EXT_INPUT_CHAIN -m set --match-set udp_sip_hosts src -p udp --dport 5060 -j ACCEPT
>> --
>> That would allow you to rebuild only the "udp_sip_hosts" ipset when the sip.conf got changed, without rebuilding the firewall. Though requires some 'ipset' command knowledge, though not complex at all.
>>
>>
>> Example 'ipset' usage in AstLinux:
>> https://github.com/astlinux-project/astlinux/blob/d95ba9c3914b135da4440cb95f32af61a41d4650/package/arnofw/aif/bin/arno-iptables-firewall#L4275 <https://github.com/astlinux-project/astlinux/blob/d95ba9c3914b135da4440cb95f32af61a41d4650/package/arnofw/aif/bin/arno-iptables-firewall#L4275> <https://github.com/astlinux-project/astlinux/blob/d95ba9c3914b135da4440cb95f32af61a41d4650/package/arnofw/aif/bin/arno-iptables-firewall#L4275> <https://github.com/astlinux-project/astlinux/blob/d95ba9c3914b135da4440cb95f32af61a41d4650/package/arnofw/aif/bin/arno-iptables-firewall#L4275>>
>>
>>
>> If you only use IPv4 a lot of the example can be simplified.
>>
>>
>> Lonnie
>>
>>
>>
>>
>>
>>
>>> On Sep 26, 2021, at 7:17 PM, Michael Knill <mic...@ip... <mailto:mic...@ip...> <mailto:mic...@ip... <mailto:mic...@ip...>>> wrote:
>>>
>>> Thanks Lonnie.
>>>
>>> Actually now that I think about it, is there any reason why the custom rule could not parse sip.conf for host=<IP Address> and open up all Public IP's?
>>> It would mean that you would need to restart the firewall every time you modified sip.conf but I'm sure we could build this into our portal very simply.
>>>
>>> Regards
>>> Michael Knill
>>>
>>> On 27/9/21, 9:47 am, "Lonnie Abelbeck" <li...@lo... <mailto:li...@lo...> <mailto:li...@lo... <mailto:li...@lo...>>> wrote:
>>>
>>> Hi Michael,
>>>
>>> With 300 rules and the same across all your boxes, I would use /mnt/kd/arno-iptables-firewall/custom-rules to define these.
>>>
>>> Very similar to the deny_ext_local() example I posted recently, but the reverse ... pass_ext_local() using -j ACCEPT
>>>
>>> Without testing, something like ...
>>> --
>>> pass_ext_local()
>>> {
>>> local proto="$1" host="$2" port="$3"
>>>
>>> echo "[CUSTOM RULE] Pass EXT->Local for Proto: $proto, Host: $host, Port: $port"
>>> iptables -A EXT_INPUT_CHAIN -s $host -p $proto --dport $port -j ACCEPT
>>> }
>>> ## uncomment to enable ##
>>> #pass_ext_local udp 1.2.3.4 5060
>>> #pass_ext_local tcp 1.2.3.0/24 5061
>>> --
>>>
>>> If you only use udp/5060, you could simplify things, maybe only one "echo" statement and a variable defining all 300 IPs. Generic shell scripting.
>>>
>>> Again untested ...
>>> --
>>> pass_ext_local_udp_sip()
>>> {
>>> local host proto="udp" port="5060" IFS
>>> local sip_hosts="1.2.3.4 1.22.33.40 1.22.33.41 1.22.33.42 1.22.33.43 1.22.33.44 1.22.33.45 1.22.33.46 1.22.33.47 1.22.33.48"
>>>
>>> echo "[CUSTOM RULE] Pass EXT->Local for UDP/5060 SIP Hosts"
>>> unset IFS
>>> for host in $sip_hosts; do
>>> iptables -A EXT_INPUT_CHAIN -s $host -p $proto --dport $port -j ACCEPT
>>> done
>>> }
>>> pass_ext_local_udp_sip
>>> --
>>>
>>> Alternatively, you could define the sip_hosts variable with a file if desired.
>>>
>>> Lonnie
>>>
>>>
>>>
>>>
>>>
>>>> On Sep 26, 2021, at 5:32 PM, Michael Knill <mic...@ip... <mailto:mic...@ip...> <mailto:mic...@ip... <mailto:mic...@ip...>>> wrote:
>>>>
>>>> Hi Group
>>>>
>>>> I'm looking to have a large number of firewall entries in Astlinux e.g. 300. They would be all the same e.g. I want to open port 5060 from multiple sites.
>>>> Is there an easier/neater way to do this other than lots of firewall entries in the Firewall Tab?
>>>>
>>>> Regards
>>>>
>>>> Michael Knill
>>>> Managing Director
>>>>
>>>> D: +61 2 6189 1360
>>>> P: +61 2 6140 4656
>>>> E: mic...@ip... <mailto:mic...@ip...> <mailto:mic...@ip... <mailto:mic...@ip...>>
>>>> W: ipcsolutions.com.au
>>>>
>>>> <image001.png>
>>>> Smarter Business Communications
>>>>
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>>>>
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>>>
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