diff -Nru vtun-3.0.4/debian/changelog vtun-3.0.4/debian/changelog
--- vtun-3.0.4/debian/changelog	2019-11-11 01:05:19.000000000 +0000
+++ vtun-3.0.4/debian/changelog	2024-02-18 14:37:36.000000000 +0000
@@ -1,3 +1,11 @@
+vtun (3.0.4-2ubuntu0.20.04.1) focal; urgency=medium
+
+  * Fix failure to run vtun in standalone server mode. (LP: #1881522)
+    - run autoupdate to update configure.in to use the syntax of
+      current version of Autoconf.
+
+ -- Sudip Mukherjee <sudipm.mukherjee@gmail.com>  Sun, 18 Feb 2024 14:37:36 +0000
+
 vtun (3.0.4-2) unstable; urgency=medium
 
   * Fix HAVE_WORKING_FORK configure check. Patch by Sylvain Rochet.
diff -Nru vtun-3.0.4/debian/control vtun-3.0.4/debian/control
--- vtun-3.0.4/debian/control	2019-11-11 00:17:37.000000000 +0000
+++ vtun-3.0.4/debian/control	2024-02-18 14:37:34.000000000 +0000
@@ -1,7 +1,8 @@
 Source: vtun
 Section: net
 Priority: optional
-Maintainer: Rodrigo Carvalho <rodrigorsdc@gmail.com>
+Maintainer: Ubuntu Developers <ubuntu-devel-discuss@lists.ubuntu.com>
+XSBC-Original-Maintainer: Rodrigo Carvalho <rodrigorsdc@gmail.com>
 Build-Depends: debhelper (>= 10), autotools-dev, liblzo2-dev,
  zlib1g-dev, libssl-dev, bison, flex
 Standards-Version: 4.4.0
diff -Nru vtun-3.0.4/debian/rules vtun-3.0.4/debian/rules
--- vtun-3.0.4/debian/rules	2019-11-11 00:17:43.000000000 +0000
+++ vtun-3.0.4/debian/rules	2024-02-18 14:37:34.000000000 +0000
@@ -18,6 +18,7 @@
 endif
 
 config.status: $(QUILT_STAMPFN) configure
+	autoupdate
 	autoconf
 	dh_testdir
 	[ -e orig_config ] || mkdir orig_config