GNU bug report logs - #48975
New firewall service

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Solene Rapenne <solene <at> perso.pw>
To: guix-patches <at> gnu.org
Subject: New firewall service
Date: Sat, 12 Jun 2021 19:19:59 +0200

Hello,

I wrote a new firewall service, I already wrote an email to guix-devel
about it and I've been suggested to submit it here.

The idea is to propose an easy way to manage your firewall. On a
personal computer or a server with no fancy network, you certainly want
to block access from the outside to all the ports except a few ones.

The configuration looks like this, currently it only supports TCP and
UDP ports. Maybe NAT could be added later or other feature, I'm opened
to suggestions.

(service firewall-service-type
  (firewall-configuration
    (udp '(53))
    (tcp '(22 70 1965))))


Here is the code, I took bits from iptables as a base and then used the
Tor service way to generate the configuration file.

diff --git a/gnu/services/networking.scm b/gnu/services/networking.scm
index 87b3d754a3..d311f95448 100644
--- a/gnu/services/networking.scm
+++ b/gnu/services/networking.scm
@@ -221,7 +221,11 @@
 
             keepalived-configuration
             keepalived-configuration?
-            keepalived-service-type))
+            keepalived-service-type
+
+            firewall-service-type
+            firewall-configuration
+            firewall-configuration?))
 
 ;;; Commentary:
 ;;;
@@ -2190,4 +2194,76 @@ of the IPFS peer-to-peer storage network.")))
                  "Run @uref{https://www.keepalived.org/, Keepalived}
 routing software.")))
 
+
+;;;
+;;; Firewall
+;;;
+
+(define-record-type* <firewall-configuration>
+  firewall-configuration make-firewall-configuration
+  firewall-configuration?
+  (tcp firewall-configuration-tcp
+       (default '()))
+  (udp firewall-configuration-udp
+       (default '())))
+
+(define (firewall-configuration->file tcp udp)
+  "Return the iptables rules from the ports list"
+  (computed-file
+   "firewall-generated-rules"
+   (with-imported-modules '((guix build utils))
+     #~(begin
+         (use-modules (guix build utils)
+                      (ice-9 match))
+         (call-with-output-file #$output
+           (lambda (out)
+             (display "\
+*filter
+:INPUT DROP
+:FORWARD DROP
+:OUTPUT ACCEPT
+-A INPUT -i lo -j ACCEPT
+-A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT\n" out)
+
+             ;; tcp rules
+             (when (not (null? (list #$@tcp)))
+               (format out "\
+~{-A INPUT -p tcp --dport ~a -j ACCEPT~%~}"
+                       (list #$@tcp)))
+
+             ;; udp rules
+             (when (not (null? (list #$@udp)))
+               (format out "\
+~{-A INPUT -p udp --dport ~a -j ACCEPT~%~}"
+                       (list #$@udp)))
+
+             (display "COMMIT\n" out)
+             #t))))))
+
+(define firewall-shepherd-service
+  (match-lambda
+    (($ <firewall-configuration> tcp udp)
+     (let* ((iptables-restore (file-append iptables "/sbin/iptables-restore"))
+            (ip6tables-restore (file-append iptables "/sbin/ip6tables-restore"))
+            (ruleset (firewall-configuration->file tcp udp)))
+       (shepherd-service
+        (documentation "Easy firewall management")
+        (provision '(firewall))
+        (start #~(lambda _
+                   (invoke #$iptables-restore  #$ruleset)
+                   (invoke #$ip6tables-restore #$ruleset)))
+        (stop #~(lambda _
+                  (invoke #$iptables-restore #$ruleset)
+                  (invoke #$ip6tables-restore #$ruleset))))))))
+
+(define firewall-service-type
+  (service-type
+   (name 'firewall)
+   (description
+    "Run @command{iptables-restore}, setting up the specified rules.")
+   (extensions
+    (list (service-extension shepherd-root-service-type
+                             (compose list firewall-shepherd-service))))))
+
+
 ;;; networking.scm ends here

Message #8 received at 48975 <at> debbugs.gnu.org (full text, mbox):

From: Jonathan Brielmaier <jonathan.brielmaier <at> web.de>
To: Solene Rapenne <solene <at> perso.pw>, 48975 <at> debbugs.gnu.org
Subject: Re: [bug#48975] New firewall service
Date: Sat, 12 Jun 2021 21:59:53 +0200

On 12.06.21 19:19, Solene Rapenne via Guix-patches via wrote:
> Hello,
>
> I wrote a new firewall service, I already wrote an email to guix-devel
> about it and I've been suggested to submit it here.
>
> The idea is to propose an easy way to manage your firewall. On a
> personal computer or a server with no fancy network, you certainly want
> to block access from the outside to all the ports except a few ones.

Hi Solene,

that is a really good idea. So I could get rid of my growing lines of
plain iptables in my Guix config :)

> The configuration looks like this, currently it only supports TCP and
> UDP ports. Maybe NAT could be added later or other feature, I'm opened
> to suggestions.
>
> (service firewall-service-type
>    (firewall-configuration
>      (udp '(53))
>      (tcp '(22 70 1965))))

I think we could improve the syntax as to be honest I'm unsure if the
listed ports are the open or the closed ones.

Maybe we could call this service simple-firewall-service-type or
something along this.

>
> Here is the code, I took bits from iptables as a base and then used the
> Tor service way to generate the configuration file.
>
> diff --git a/gnu/services/networking.scm b/gnu/services/networking.scm
> index 87b3d754a3..d311f95448 100644
> --- a/gnu/services/networking.scm
> +++ b/gnu/services/networking.scm

You should add a copyright line for yourself at the top of the file.

> @@ -221,7 +221,11 @@
>
>               keepalived-configuration
>               keepalived-configuration?
> -            keepalived-service-type))
> +            keepalived-service-type
> +
> +            firewall-service-type
> +            firewall-configuration
> +            firewall-configuration?))
>
>   ;;; Commentary:
>   ;;;
> @@ -2190,4 +2194,76 @@ of the IPFS peer-to-peer storage network.")))
>                    "Run @uref{https://www.keepalived.org/, Keepalived}
>   routing software.")))
>
> +
> +;;;
> +;;; Firewall
> +;;;
> +
> +(define-record-type* <firewall-configuration>
> +  firewall-configuration make-firewall-configuration
> +  firewall-configuration?
> +  (tcp firewall-configuration-tcp
> +       (default '()))
> +  (udp firewall-configuration-udp
> +       (default '())))
> +
> +(define (firewall-configuration->file tcp udp)
> +  "Return the iptables rules from the ports list"
> +  (computed-file
> +   "firewall-generated-rules"
> +   (with-imported-modules '((guix build utils))
> +     #~(begin
> +         (use-modules (guix build utils)
> +                      (ice-9 match))
> +         (call-with-output-file #$output
> +           (lambda (out)
> +             (display "\
> +*filter
> +:INPUT DROP
> +:FORWARD DROP
> +:OUTPUT ACCEPT
> +-A INPUT -i lo -j ACCEPT
> +-A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT\n" out)
> +
> +             ;; tcp rules
> +             (when (not (null? (list #$@tcp)))
> +               (format out "\
> +~{-A INPUT -p tcp --dport ~a -j ACCEPT~%~}"
> +                       (list #$@tcp)))
> +
> +             ;; udp rules
> +             (when (not (null? (list #$@udp)))
> +               (format out "\
> +~{-A INPUT -p udp --dport ~a -j ACCEPT~%~}"
> +                       (list #$@udp)))
> +
> +             (display "COMMIT\n" out)
> +             #t))))))

I'm not an iptables expert but does this config block/open IPv4 as well
as IPv6?

> +(define firewall-shepherd-service
> +  (match-lambda
> +    (($ <firewall-configuration> tcp udp)
> +     (let* ((iptables-restore (file-append iptables "/sbin/iptables-restore"))
> +            (ip6tables-restore (file-append iptables "/sbin/ip6tables-restore"))
> +            (ruleset (firewall-configuration->file tcp udp)))
> +       (shepherd-service
> +        (documentation "Easy firewall management")
> +        (provision '(firewall))
> +        (start #~(lambda _
> +                   (invoke #$iptables-restore  #$ruleset)
> +                   (invoke #$ip6tables-restore #$ruleset)))
> +        (stop #~(lambda _
> +                  (invoke #$iptables-restore #$ruleset)
> +                  (invoke #$ip6tables-restore #$ruleset))))))))
> +
> +(define firewall-service-type
> +  (service-type
> +   (name 'firewall)
> +   (description
> +    "Run @command{iptables-restore}, setting up the specified rules.")
> +   (extensions
> +    (list (service-extension shepherd-root-service-type
> +                             (compose list firewall-shepherd-service))))))
> +
> +
>   ;;; networking.scm ends here
>
>
>

Message #11 received at 48975 <at> debbugs.gnu.org (full text, mbox):

From: Solene Rapenne <solene <at> perso.pw>
To: Jonathan Brielmaier <jonathan.brielmaier <at> web.de>
Cc: 48975 <at> debbugs.gnu.org
Subject: Re: [bug#48975] New firewall service
Date: Sun, 13 Jun 2021 00:13:58 +0200

On Sat, 12 Jun 2021 21:59:53 +0200
Jonathan Brielmaier <jonathan.brielmaier <at> web.de>:

> On 12.06.21 19:19, Solene Rapenne via Guix-patches via wrote:
> > Hello,
> >
> > I wrote a new firewall service, I already wrote an email to guix-devel
> > about it and I've been suggested to submit it here.
> >
> > The idea is to propose an easy way to manage your firewall. On a
> > personal computer or a server with no fancy network, you certainly want
> > to block access from the outside to all the ports except a few ones.  
> 
> Hi Solene,
> 
> that is a really good idea. So I could get rid of my growing lines of
> plain iptables in my Guix config :)
> 
> > The configuration looks like this, currently it only supports TCP and
> > UDP ports. Maybe NAT could be added later or other feature, I'm opened
> > to suggestions.
> >
> > (service firewall-service-type
> >    (firewall-configuration
> >      (udp '(53))
> >      (tcp '(22 70 1965))))  
> 
> I think we could improve the syntax as to be honest I'm unsure if the
> listed ports are the open or the closed ones.
> 
> Maybe we could call this service simple-firewall-service-type or
> something along this.

hello, thanks a lot for your feedback.

I have no argument for a rename, as long as it's understandable.
As it's simple, I like simple-firewall.

Do you think this would be easier to understand by adding "open"
to the names?

(service simple-firewall-service-type
  (simple-firewall-configuration
    (open-udp '(53))
    (open-tcp '(22 ...))))

I think we must decided if ICMP is allowed by default or not and
the syntax to enable/disable it. Maybe this? I would disable it by
default.

    (allow-icmp? #t)

If you stop simple-firewall with the current code, it will block
every inbound ports, I'm not sure if it's the correct way to proceed, I suppose
it should flush absolutely everything.

To match most simple use case, a simple NAT and port redirection
could be done too.

    ;; do NAT on eth0 and set the according sysctl
    (nat-on "eth0")

    ;; redirect incoming connections on ports 22 and 8080 to another box
    (redirect '((22 "192.168.1.50:22")
                (8080 "192.168.1.50:80"))
 
> >
> > Here is the code, I took bits from iptables as a base and then used the
> > Tor service way to generate the configuration file.
> >
> > diff --git a/gnu/services/networking.scm b/gnu/services/networking.scm
> > index 87b3d754a3..d311f95448 100644
> > --- a/gnu/services/networking.scm
> > +++ b/gnu/services/networking.scm  
> 
> You should add a copyright line for yourself at the top of the file.
> 

I've been told it's not mandatory.  I have no issue adding it though.

I found a ^L character at many paces in networking.scm, I don't
know if its appearance is legit or not. I think it's a garbage
character that got copy/pasted over and over. I copied it just in
case.

> >
> > +
> > +;;;
> > +;;; Firewall
> > +;;;
> > +

Message #14 received at 48975 <at> debbugs.gnu.org (full text, mbox):

From: Arun Isaac <arunisaac <at> systemreboot.net>
To: Solene Rapenne <solene <at> perso.pw>, 48975 <at> debbugs.gnu.org
Cc: Jonathan Brielmaier <jonathan.brielmaier <at> web.de>
Subject: Re: [bug#48975] New firewall service
Date: Sun, 13 Jun 2021 14:59:31 +0530

[Message part 1 (text/plain, inline)]

Hi Solene,

Thanks for the great work! I wrote the iptables service in the hope of
some day extending it to something like this, but you've beaten me to
it! :-) Some feedback follows.

Your implementation duplicates some of the code in the iptables
service. How about making it simply /extend/ the iptables service with
the generated rules? This way, you won't have to handle the start/stop
iptables-restore gexps. The iptables service, when stopped, already has
the correct behaviour of opening all ports.

WDYT?

Regards,
Arun

[signature.asc (application/pgp-signature, inline)]

Message #17 received at 48975 <at> debbugs.gnu.org (full text, mbox):

From: antlers <autumnalantlers <at> gmail.com>
To: 48975 <at> debbugs.gnu.org
Cc: antlers <antlers <at> luris.net>
Subject: [PATCH] gnu: simple-firewall-service: Add a simple service wrapping
 iptables
Date: Fri,  4 Nov 2022 00:25:50 -0700

From: antlers <antlers <at> luris.net>

 * gnu/services/networking.scm (simple-firewall-service): Add.
   (iptables-service): Allow a crude sort of service extension.

I tried out a keyword-based syntax:
```
(simple-firewall-configuration
  (allow-forwarding? #t)
  (allowed-ports '(#:both 51234
                   #:tcp  80 443
                   #:udp  4444))
```
But kept the more verbose tcp and udp fields because I don't want
people to have to use quasiquotes to splice in evaluated port-numbers
after the keywords.

I like the suggestion that there should be a field for redirecting
packets, whether to loopback or another box, as it took me a while to
learn about eg. masquerading last time I needed to set something like
that up. Not sure what command would be equivalent to the NAT
suggestion?

I guess nftables has superseded iptables, but I'm not as familiar with
it? Perhaps I can add it as a second back-end in the future. My
primary concern right now is a pure Scheme interface for networking
configuration; most notably via service inheritance! Simple-firewall
now lets you open ports via extensions in other services; in order for
this option to be widely available, perhaps it's the
{nf,ip}tables-services that should be extensible? It's a tricky
problem atm because we don't really want services that need ports
depending on a specific backend, there are existing API's, they use
plain-file's over structs or strings, and rule orders need to be
really specific/coordinated. Idk, maybe that isn't something we really
want in the first place, but it sure feels good from a configuration /
organizational point-of-view. Happy to tweak this again if anyone has
ideas.
---
 gnu/services/networking.scm | 79 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 77 insertions(+), 2 deletions(-)

diff --git a/gnu/services/networking.scm b/gnu/services/networking.scm
index 19aba8c266..0866c10b34 100644
--- a/gnu/services/networking.scm
+++ b/gnu/services/networking.scm
@@ -18,6 +18,8 @@
 ;;; Copyright © 2021 Christine Lemmer-Webber <cwebber <at> dustycloud.org>
 ;;; Copyright © 2021 Maxime Devos <maximedevos <at> telenet.be>
 ;;; Copyright © 2021 Guillaume Le Vaillant <glv <at> posteo.net>
+;;; Copyright © 2021 Solene Rapenne
+;;; Copyright © 2022 antlers <autumnalantlers <at> gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -225,7 +227,11 @@ (define-module (gnu services networking)
 
             keepalived-configuration
             keepalived-configuration?
-            keepalived-service-type))
+            keepalived-service-type
+
+            simple-firewall-service-type
+            simple-firewall-configuration
+            simple-firewall-configuration?))
 
 ;;; Commentary:
 ;;;
@@ -1721,7 +1727,13 @@ (define iptables-service-type
     "Run @command{iptables-restore}, setting up the specified rules.")
    (extensions
     (list (service-extension shepherd-root-service-type
-                             (compose list iptables-shepherd-service))))))
+                             (compose list iptables-shepherd-service))))
+   ;; Some services extend iptables, but such services are mutually exclusive,
+   ;; and should be either extended directly or superseded entirely depending
+   ;; the complexity of your desired configuration.
+   (compose identity)
+   (extend (lambda (config entries)
+             (last entries)))))
 
 ;;;
 ;;; nftables
@@ -2186,4 +2198,67 @@ (define keepalived-service-type
                  "Run @uref{https://www.keepalived.org/, Keepalived}
 routing software.")))
 
+
+;;;
+;;; Simple Firewall
+;;;
+
+(define-record-type* <simple-firewall-configuration>
+  simple-firewall-configuration make-simple-firewall-configuration
+  simple-firewall-configuration?
+  (allow-icmp? simple-firewall-configuration-allow-icmp?
+               (default #f))
+  (allow-forwarding? simple-firewall-configuration-allow-forwarding?
+                     (default #f))
+
+  (open-tcp-ports simple-firewall-configuration-open-tcp-ports
+                 (default '()))
+  (open-udp-ports simple-firewall-configuration-open-udp-ports
+                 (default '())))
+
+(define simple-firewall-configuration->iptables-rules
+  (match-lambda
+    (($ <simple-firewall-configuration>
+        allow-icmp? allow-forwarding?
+        open-tcp-ports open-udp-ports)
+     (string-join
+       `("*filter"
+         ":INPUT DROP"
+         ,(string-append ":FORWARD " (if allow-forwarding? "ACCEPT" "DROP"))
+         ":OUTPUT ACCEPT"
+         "-A INPUT -i lo -j ACCEPT"
+         "-A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT"
+         ,@(unless allow-icmp? '("-A INPUT -p icmp   -j DROP"
+                                 "-A INPUT -p icmpv6 -j DROP"))
+         ,@(map (cut string-append "-A INPUT -p tcp --dport " <>  " -j ACCEPT") (map number->string open-tcp-ports))
+         ,@(map (cut string-append "-A INPUT -p udp --dport " <>  " -j ACCEPT") (map number->string open-udp-ports))
+         "-A INPUT -j REJECT --reject-with icmp-port-unreachable"
+         "COMMIT")
+       "\n" 'suffix))))
+
+(define (simple-firewall-configuration->iptables-configuration config)
+  (let ((rules (simple-firewall-configuration->iptables-rules config)))
+    (iptables-configuration
+      (ipv4-rules (plain-file "iptables.rules" rules))
+      (ipv6-rules (plain-file "ip6tables.rules" rules)))))
+
+(define simple-firewall-service-type
+  (service-type
+   (name 'simple-firewall)
+   (description
+    "Run @command{iptables-restore}, setting up the specified rules.")
+   (extensions
+     (list (service-extension iptables-service-type
+                              simple-firewall-configuration->iptables-configuration)))
+   (compose concatenate)
+   (extend (lambda (config entries)
+             (simple-firewall-configuration
+              (inherit config)
+              (open-tcp-ports
+                (concatenate (map simple-firewall-configuration-open-tcp-ports
+                                  (cons config entries))))
+              (open-udp-ports
+                (concatenate (map simple-firewall-configuration-open-udp-ports
+                                  (cons config entries)))))))))
+
 ;;; networking.scm ends here
-- 
2.38.0

Message #20 received at 48975 <at> debbugs.gnu.org (full text, mbox):

From: antlers <autumnalantlers <at> gmail.com>
To: 48975 <at> debbugs.gnu.org
Subject: Re: [PATCH] gnu: simple-firewall-service: Add a simple service
 wrapping iptables
Date: Sun, 6 Nov 2022 12:39:26 -0800

[Message part 1 (text/plain, inline)]

After googling around a bit it looks like the `filter*` and `COMMIT`
commands in iptables configurations do in fact form a transactional block
that would allow us to accept additional plain-files via extensions and
just concatenate them, it's that's a road we want to go down

On Fri, Nov 4, 2022 at 12:26 AM antlers <autumnalantlers <at> gmail.com> wrote:

> From: antlers <antlers <at> luris.net>
>
>  * gnu/services/networking.scm (simple-firewall-service): Add.
>    (iptables-service): Allow a crude sort of service extension.
>
> I tried out a keyword-based syntax:
> ```
> (simple-firewall-configuration
>   (allow-forwarding? #t)
>   (allowed-ports '(#:both 51234
>                    #:tcp  80 443
>                    #:udp  4444))
> ```
> But kept the more verbose tcp and udp fields because I don't want
> people to have to use quasiquotes to splice in evaluated port-numbers
> after the keywords.
>
> I like the suggestion that there should be a field for redirecting
> packets, whether to loopback or another box, as it took me a while to
> learn about eg. masquerading last time I needed to set something like
> that up. Not sure what command would be equivalent to the NAT
> suggestion?
>
> I guess nftables has superseded iptables, but I'm not as familiar with
> it? Perhaps I can add it as a second back-end in the future. My
> primary concern right now is a pure Scheme interface for networking
> configuration; most notably via service inheritance! Simple-firewall
> now lets you open ports via extensions in other services; in order for
> this option to be widely available, perhaps it's the
> {nf,ip}tables-services that should be extensible? It's a tricky
> problem atm because we don't really want services that need ports
> depending on a specific backend, there are existing API's, they use
> plain-file's over structs or strings, and rule orders need to be
> really specific/coordinated. Idk, maybe that isn't something we really
> want in the first place, but it sure feels good from a configuration /
> organizational point-of-view. Happy to tweak this again if anyone has
> ideas.
> ---
>  gnu/services/networking.scm | 79 ++++++++++++++++++++++++++++++++++++-
>  1 file changed, 77 insertions(+), 2 deletions(-)
>
> diff --git a/gnu/services/networking.scm b/gnu/services/networking.scm
> index 19aba8c266..0866c10b34 100644
> --- a/gnu/services/networking.scm
> +++ b/gnu/services/networking.scm
> @@ -18,6 +18,8 @@
>  ;;; Copyright © 2021 Christine Lemmer-Webber <cwebber <at> dustycloud.org>
>  ;;; Copyright © 2021 Maxime Devos <maximedevos <at> telenet.be>
>  ;;; Copyright © 2021 Guillaume Le Vaillant <glv <at> posteo.net>
> +;;; Copyright © 2021 Solene Rapenne
> +;;; Copyright © 2022 antlers <autumnalantlers <at> gmail.com>
>  ;;;
>  ;;; This file is part of GNU Guix.
>  ;;;
> @@ -225,7 +227,11 @@ (define-module (gnu services networking)
>
>              keepalived-configuration
>              keepalived-configuration?
> -            keepalived-service-type))
> +            keepalived-service-type
> +
> +            simple-firewall-service-type
> +            simple-firewall-configuration
> +            simple-firewall-configuration?))
>
>  ;;; Commentary:
>  ;;;
> @@ -1721,7 +1727,13 @@ (define iptables-service-type
>      "Run @command{iptables-restore}, setting up the specified rules.")
>     (extensions
>      (list (service-extension shepherd-root-service-type
> -                             (compose list iptables-shepherd-service))))))
> +                             (compose list iptables-shepherd-service))))
> +   ;; Some services extend iptables, but such services are mutually
> exclusive,
> +   ;; and should be either extended directly or superseded entirely
> depending
> +   ;; the complexity of your desired configuration.
> +   (compose identity)
> +   (extend (lambda (config entries)
> +             (last entries)))))
>
>  ;;;
>  ;;; nftables
> @@ -2186,4 +2198,67 @@ (define keepalived-service-type
>                   "Run @uref{https://www.keepalived.org/, Keepalived}
>  routing software.")))
>
> +
> +;;;
> +;;; Simple Firewall
> +;;;
> +
> +(define-record-type* <simple-firewall-configuration>
> +  simple-firewall-configuration make-simple-firewall-configuration
> +  simple-firewall-configuration?
> +  (allow-icmp? simple-firewall-configuration-allow-icmp?
> +               (default #f))
> +  (allow-forwarding? simple-firewall-configuration-allow-forwarding?
> +                     (default #f))
> +
> +  (open-tcp-ports simple-firewall-configuration-open-tcp-ports
> +                 (default '()))
> +  (open-udp-ports simple-firewall-configuration-open-udp-ports
> +                 (default '())))
> +
> +(define simple-firewall-configuration->iptables-rules
> +  (match-lambda
> +    (($ <simple-firewall-configuration>
> +        allow-icmp? allow-forwarding?
> +        open-tcp-ports open-udp-ports)
> +     (string-join
> +       `("*filter"
> +         ":INPUT DROP"
> +         ,(string-append ":FORWARD " (if allow-forwarding? "ACCEPT"
> "DROP"))
> +         ":OUTPUT ACCEPT"
> +         "-A INPUT -i lo -j ACCEPT"
> +         "-A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT"
> +         ,@(unless allow-icmp? '("-A INPUT -p icmp   -j DROP"
> +                                 "-A INPUT -p icmpv6 -j DROP"))
> +         ,@(map (cut string-append "-A INPUT -p tcp --dport " <>  " -j
> ACCEPT") (map number->string open-tcp-ports))
> +         ,@(map (cut string-append "-A INPUT -p udp --dport " <>  " -j
> ACCEPT") (map number->string open-udp-ports))
> +         "-A INPUT -j REJECT --reject-with icmp-port-unreachable"
> +         "COMMIT")
> +       "\n" 'suffix))))
> +
> +(define (simple-firewall-configuration->iptables-configuration config)
> +  (let ((rules (simple-firewall-configuration->iptables-rules config)))
> +    (iptables-configuration
> +      (ipv4-rules (plain-file "iptables.rules" rules))
> +      (ipv6-rules (plain-file "ip6tables.rules" rules)))))
> +
> +(define simple-firewall-service-type
> +  (service-type
> +   (name 'simple-firewall)
> +   (description
> +    "Run @command{iptables-restore}, setting up the specified rules.")
> +   (extensions
> +     (list (service-extension iptables-service-type
> +
> simple-firewall-configuration->iptables-configuration)))
> +   (compose concatenate)
> +   (extend (lambda (config entries)
> +             (simple-firewall-configuration
> +              (inherit config)
> +              (open-tcp-ports
> +                (concatenate (map
> simple-firewall-configuration-open-tcp-ports
> +                                  (cons config entries))))
> +              (open-udp-ports
> +                (concatenate (map
> simple-firewall-configuration-open-udp-ports
> +                                  (cons config entries)))))))))
> +
>  ;;; networking.scm ends here
> --
> 2.38.0
>
>

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