[PATCH] Fix tcpdump.

[Ricardo Wurmus]

Hi Guix,

libpcap comes with a couple of backends that are disabled by default.
Among those available backends is “pcap-linux”.  By default the only
backends are

    pcap-null
    pcap-usb-linux
    pcap-can-linux
    pcap-netfilter-linux
    pcap-common

‘netfilter-linux’ doesn’t work out of the box and I think it requires
loading iptables/netfilter kernel modules (I have not yet found the
correct modules to load, so I can only guess).  When “--with-pcap=linux”
is passed “pcap-linux.c” is compiled as well, which makes tcpdump work
out of the box without the need to load any further modules.

Thanks to Ludovic for providing a crucial bit of information!

~~ Ricardo

>From 7ca2d0dc5cc1232605e2b78167ea3ae5c92be531 Mon Sep 17 00:00:00 2001
From: Ricardo Wurmus <address@hidden>
Date: Wed, 15 Jul 2015 16:11:50 +0200
Subject: [PATCH] gnu: libpcap: Enable plain "linux" backend.

* gnu/packages/admin.scm (libpcap)[arguments]: Add "--with-pcap=linux"
  configure flag.
---
 gnu/packages/admin.scm | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gnu/packages/admin.scm b/gnu/packages/admin.scm
index c96e116..5b56599 100644
--- a/gnu/packages/admin.scm
+++ b/gnu/packages/admin.scm
@@ -476,7 +476,8 @@ tools: server, client, and relay agent.")
                 "14wyjywrdi1ikaj6yc9c72m6m2r64z94lb0gm7k1a3q6q5cj3scs"))))
     (build-system gnu-build-system)
     (native-inputs `(("bison" ,bison) ("flex" ,flex)))
-    (arguments '(#:tests? #f))                    ; no 'check' target
+    (arguments '(#:configure-flags '("--with-pcap=linux")
+                 #:tests? #f))                    ; no 'check' target
     (home-page "http://www.tcpdump.org";)
     (synopsis "Network packet capture library")
     (description
-- 
2.4.3