op-mode: T2874: Add new utill for mtu-check

2 files changed, 86 insertions, 0 deletions

diff --git a/op-mode-definitions/force-mtu-host.xml b/op-mode-definitions/force-mtu-host.xml
new file mode 100644
index 000000000..b92179f11
--- /dev/null
+++ b/op-mode-definitions/force-mtu-host.xml
@@ -0,0 +1,34 @@
+<?xml version="1.0"?>
+<interfaceDefinition>
+  <node name="force">
+    <children>
+      <node name="mtu">
+        <properties>
+          <help>Show MTU max value for remote host protocol TCP</help>
+        </properties>
+        <children>
+          <tagNode name="host">
+            <properties>
+              <help>IP address of the remote host</help>
+              <completionHelp>
+                <list>&lt;hostname&gt; &lt;x.x.x.x&gt; &lt;h:h:h:h:h:h:h:h&gt;</list>
+              </completionHelp>
+            </properties>
+            <command>${vyos_op_scripts_dir}/force_mtu_host.sh $4</command>
+            <children>
+              <tagNode name="interface">
+                <properties>
+                  <help>Source interface</help>
+                  <completionHelp>
+                    <script>${vyos_completion_dir}/list_interfaces.py</script>
+                  </completionHelp>
+                </properties>
+                <command>${vyos_op_scripts_dir}/force_mtu_host.sh $4 $6</command>
+              </tagNode>
+            </children>
+          </tagNode>
+        </children>
+      </node>
+    </children>
+  </node>
+</interfaceDefinition>
diff --git a/src/op_mode/force_mtu_host.sh b/src/op_mode/force_mtu_host.sh
new file mode 100755
index 000000000..02955c729
--- /dev/null
+++ b/src/op_mode/force_mtu_host.sh
@@ -0,0 +1,52 @@
+#!/usr/bin/env bash
+#
+# Module: vyos-show-ram.sh
+# Displays memory usage information in minimalistic format
+#
+# Copyright (C) 2020 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+target=$1
+interface=$2
+
+# IPv4 header 20 byte + TCP header 20 byte
+ipv4_overhead=40
+
+# IPv6 headter 40 byte + TCP header 20 byte
+ipv6_overhead=60
+
+# If no arguments
+if [[ $# -eq 0 ]] ; then
+    echo "Target host not defined"
+    exit 1
+fi
+
+# If one argument, it's ip address. If 2, the second arg "interface"
+if [[ $# -eq 1 ]] ; then
+    mtu=$(sudo nmap -T4 --script path-mtu -F $target | grep "PMTU" | awk {'print $NF'})
+elif [[ $# -eq 2 ]]; then
+    mtu=$(sudo nmap -T4 -e $interface --script path-mtu -F $target | grep "PMTU" | awk {'print $NF'})
+fi
+
+tcpv4_mss=$(($mtu-$ipv4_overhead))
+tcpv6_mss=$(($mtu-$ipv6_overhead))
+
+echo "
+Recommended maximum values (or less) for target $target:
+---
+MTU:     $mtu
+TCP-MSS: $tcpv4_mss
+TCP-MSS_IPv6: $tcpv6_mss
+"
+