diff --git a/vpnsetup_alpine.sh b/vpnsetup_alpine.sh
index bf538db..bd461f3 100755
--- a/vpnsetup_alpine.sh
+++ b/vpnsetup_alpine.sh
@@ -230,7 +230,7 @@ get_helper_scripts() {
 }
 
 get_swan_ver() {
-  SWAN_VER=4.7
+  SWAN_VER=4.9
   base_url="https://github.com/hwdsl2/vpn-extras/releases/download/v1.0.0"
   swan_ver_url="$base_url/v1-$os_type-$os_ver-swanver"
   swan_ver_latest=$(wget -t 2 -T 10 -qO- "$swan_ver_url" | head -n 1)
@@ -284,7 +284,6 @@ WERROR_CFLAGS=-w -s
 USE_DNSSEC=false
 USE_DH2=true
 FINALNSSDIR=/etc/ipsec.d
-USE_GLIBC_KERN_FLIP_HEADERS=true
 EOF
     NPROCS=$(grep -c ^processor /proc/cpuinfo)
     [ -z "$NPROCS" ] && NPROCS=1
diff --git a/vpnsetup_amzn.sh b/vpnsetup_amzn.sh
index 7566f22..6eafb22 100755
--- a/vpnsetup_amzn.sh
+++ b/vpnsetup_amzn.sh
@@ -244,7 +244,7 @@ get_helper_scripts() {
 }
 
 get_swan_ver() {
-  SWAN_VER=4.7
+  SWAN_VER=4.9
   base_url="https://github.com/hwdsl2/vpn-extras/releases/download/v1.0.0"
   swan_ver_url="$base_url/v1-amzn-2-swanver"
   swan_ver_latest=$(wget -t 2 -T 10 -qO- "$swan_ver_url" | head -n 1)
@@ -298,6 +298,8 @@ WERROR_CFLAGS=-w -s
 USE_DNSSEC=false
 USE_DH2=true
 USE_NSS_KDF=false
+USE_LINUX_AUDIT=false
+USE_SECCOMP=false
 FINALNSSDIR=/etc/ipsec.d
 EOF
     if ! grep -qs IFLA_XFRM_LINK /usr/include/linux/if_link.h; then
diff --git a/vpnsetup_centos.sh b/vpnsetup_centos.sh
index d3562f6..5e233bf 100755
--- a/vpnsetup_centos.sh
+++ b/vpnsetup_centos.sh
@@ -350,7 +350,7 @@ get_helper_scripts() {
 }
 
 get_swan_ver() {
-  SWAN_VER=4.7
+  SWAN_VER=4.9
   base_url="https://github.com/hwdsl2/vpn-extras/releases/download/v1.0.0"
   swan_ver_url="$base_url/v1-$os_type-$os_ver-swanver"
   swan_ver_latest=$(wget -t 2 -T 10 -qO- "$swan_ver_url" | head -n 1)
@@ -404,6 +404,8 @@ WERROR_CFLAGS=-w -s
 USE_DNSSEC=false
 USE_DH2=true
 USE_NSS_KDF=false
+USE_LINUX_AUDIT=false
+USE_SECCOMP=false
 FINALNSSDIR=/etc/ipsec.d
 EOF
     if ! grep -qs IFLA_XFRM_LINK /usr/include/linux/if_link.h; then
diff --git a/vpnsetup_ubuntu.sh b/vpnsetup_ubuntu.sh
index 5be3bf6..6090e9b 100755
--- a/vpnsetup_ubuntu.sh
+++ b/vpnsetup_ubuntu.sh
@@ -260,6 +260,34 @@ install_vpn_pkgs() {
   ) || exiterr2
 }
 
+install_nss_pkgs() {
+  os_arch=$(uname -m | tr -dc 'A-Za-z0-9_-')
+  if [ "$os_type" = "ubuntu" ] && [ "$os_ver" = "bustersid" ] && [ "$os_arch" = "x86_64" ]; then
+    nss_url1="https://mirrors.kernel.org/ubuntu/pool/main/n/nss"
+    nss_url2="https://mirrors.kernel.org/ubuntu/pool/universe/n/nss"
+    nss_deb1="libnss3_3.49.1-1ubuntu1.8_amd64.deb"
+    nss_deb2="libnss3-dev_3.49.1-1ubuntu1.8_amd64.deb"
+    nss_deb3="libnss3-tools_3.49.1-1ubuntu1.8_amd64.deb"
+    bigecho "Installing NSS packages on Ubuntu 18.04..."
+    if tmpdir=$(mktemp --tmpdir -d vpn.XXXXX 2>/dev/null); then
+      nss_dl=0
+      if wget -t 3 -T 30 -q -O "$tmpdir/1.deb" "$nss_url1/$nss_deb1" \
+        && wget -t 3 -T 30 -q -O "$tmpdir/2.deb" "$nss_url1/$nss_deb2" \
+        && wget -t 3 -T 30 -q -O "$tmpdir/3.deb" "$nss_url2/$nss_deb3"; then
+        apt-get -yqq install "$tmpdir/1.deb" "$tmpdir/2.deb" "$tmpdir/3.deb" >/dev/null
+      else
+        nss_dl=1
+        echo "Error: Could not download NSS packages." >&2
+      fi
+      /bin/rm -f "$tmpdir/1.deb" "$tmpdir/2.deb" "$tmpdir/3.deb"
+      /bin/rmdir "$tmpdir"
+      [ "$nss_dl" = 1 ] && exit 1
+    else
+      exiterr "Could not create temporary directory."
+    fi
+  fi
+}
+
 install_fail2ban() {
   bigecho "Installing Fail2Ban to protect SSH..."
   (
@@ -290,7 +318,7 @@ get_helper_scripts() {
 }
 
 get_swan_ver() {
-  SWAN_VER=4.7
+  SWAN_VER=4.9
   base_url="https://github.com/hwdsl2/vpn-extras/releases/download/v1.0.0"
   swan_ver_url="$base_url/v1-$os_type-$os_ver-swanver"
   swan_ver_latest=$(wget -t 2 -T 10 -qO- "$swan_ver_url" | head -n 1)
@@ -731,6 +759,7 @@ vpnsetup() {
   install_setup_pkgs
   detect_ip
   install_vpn_pkgs
+  install_nss_pkgs
   install_fail2ban
   get_helper_scripts
   get_libreswan