Revert "networkd: change UseMTU default to true. (#6837)" (#6950)

This reverts commit 22043e4317ecd2bc7834b48a6d364de76bb26d91.
UseMTU is broken on real hardware and should not be enabled by default.

diff --git a/NEWS b/NEWS
index dc5c8acdff483052d289b66e3ae64b8df5a9af58..ecff646aa505796c6efd57582f9a5fdc5cba2f56 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -16,11 +16,6 @@ CHANGES WITH 235:
           respectively. They complement the existing "set-log-level" and
           "set-log-target" verbs, which can be used to change those values.
 
-        * systemd-networkd .network DHCP setting UseMTU default has changed
-          from false to true. Meaning, DHCP server advertised MTU setting is
-          now applied by default. This resolves networking issues on low-mtu
-          networks.
-
         * journald.conf gained a new boolean setting ReadKMsg= which defaults
           to on. If turned off kernel log messages will not be read by
           systemd-journald and not be included in the logs. It also gained a

diff --git a/man/systemd.network.xml b/man/systemd.network.xml
index 40e302c90d02e31ba58401925098834a76a97bb8..b1759677f98f56508efdf3fd2c02a484fed72ad0 100644 (file)
--- a/man/systemd.network.xml
+++ b/man/systemd.network.xml
@@ -1063,7 +1063,7 @@
           <listitem>
             <para>When true, the interface maximum transmission unit
             from the DHCP server will be used on the current link.
-            Defaults to true.</para>
+            Defaults to false.</para>
           </listitem>
         </varlistentry>
         <varlistentry>

diff --git a/src/network/networkd-network.c b/src/network/networkd-network.c
index 72ba0916c9483407a1eb679a0b2102025b56cc44..3a7eb2c2a8a873bf0afd64521ab85331dc58ba57 100644 (file)
--- a/src/network/networkd-network.c
+++ b/src/network/networkd-network.c
@@ -223,7 +223,8 @@ static int network_load_one(Manager *manager, const char *filename) {
          * even if they are commented in the man?
          * These vars might be overwriten by network_apply_anonymize_if_set */
         network->dhcp_vendor_class_identifier = false;
-        network->dhcp_use_mtu = true;
+        /* NOTE: from man: UseMTU=... Defaults to false*/
+        network->dhcp_use_mtu = false;
         /* NOTE: from man: UseTimezone=... Defaults to "no".*/
         network->dhcp_use_timezone = false;