diff --git a/plugins/inputs/syslog/testcases/rfc5424_best_effort_toolong_appname/expected.err b/plugins/inputs/syslog/testcases/rfc5424_best_effort_toolong_appname/expected.err
new file mode 100644
index 000000000..a7b4e4e3a
--- /dev/null
+++ b/plugins/inputs/syslog/testcases/rfc5424_best_effort_toolong_appname/expected.err
@@ -0,0 +1 @@
+expecting an app-name (from 1 to max 48 US-ASCII characters) or a nil value
\ No newline at end of file
diff --git a/plugins/inputs/syslog/testcases/rfc5424_best_effort_toolong_appname/expected.out b/plugins/inputs/syslog/testcases/rfc5424_best_effort_toolong_appname/expected.out
new file mode 100644
index 000000000..7111aee8b
--- /dev/null
+++ b/plugins/inputs/syslog/testcases/rfc5424_best_effort_toolong_appname/expected.out
@@ -0,0 +1 @@
+syslog,facility=local4,hostname=mymachine.example.com,severity=err,source=127.0.0.1 facility_code=20i,severity_code=3i,timestamp=1065910455003000000i,version=1u 1708596337291396420
diff --git a/plugins/inputs/syslog/testcases/rfc5424_best_effort_toolong_appname/input.txt b/plugins/inputs/syslog/testcases/rfc5424_best_effort_toolong_appname/input.txt
new file mode 100644
index 000000000..2ed91f0f9
--- /dev/null
+++ b/plugins/inputs/syslog/testcases/rfc5424_best_effort_toolong_appname/input.txt
@@ -0,0 +1 @@
+<163>1 2003-10-11T22:14:15.003Z mymachine.example.com ALongApplicationNameContainingMoreThanTheAllowed48Character - ID47 - BOM'su root' failed for lonvick on /dev/pts/8
diff --git a/plugins/inputs/syslog/testcases/rfc5426_best_effort_udp/telegraf.conf b/plugins/inputs/syslog/testcases/rfc5424_best_effort_toolong_appname/telegraf.conf
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_best_effort_udp/telegraf.conf
rename to plugins/inputs/syslog/testcases/rfc5424_best_effort_toolong_appname/telegraf.conf
diff --git a/plugins/inputs/syslog/testcases/rfc5426_best_effort_udp/expected.out b/plugins/inputs/syslog/testcases/rfc5424_best_effort_udp/expected.out
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_best_effort_udp/expected.out
rename to plugins/inputs/syslog/testcases/rfc5424_best_effort_udp/expected.out
diff --git a/plugins/inputs/syslog/testcases/rfc5426_best_effort_udp/input.txt b/plugins/inputs/syslog/testcases/rfc5424_best_effort_udp/input.txt
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_best_effort_udp/input.txt
rename to plugins/inputs/syslog/testcases/rfc5424_best_effort_udp/input.txt
diff --git a/plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_average/telegraf.conf b/plugins/inputs/syslog/testcases/rfc5424_best_effort_udp/telegraf.conf
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_average/telegraf.conf
rename to plugins/inputs/syslog/testcases/rfc5424_best_effort_udp/telegraf.conf
diff --git a/plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_average/expected.out b/plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_average/expected.out
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_average/expected.out
rename to plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_average/expected.out
diff --git a/plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_average/input.txt b/plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_average/input.txt
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_average/input.txt
rename to plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_average/input.txt
diff --git a/plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_max/telegraf.conf b/plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_average/telegraf.conf
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_max/telegraf.conf
rename to plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_average/telegraf.conf
diff --git a/plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_max/expected.out b/plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_max/expected.out
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_max/expected.out
rename to plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_max/expected.out
diff --git a/plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_max/input.txt b/plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_max/input.txt
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_max/input.txt
rename to plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_max/input.txt
diff --git a/plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_min_incomplete/telegraf.conf b/plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_max/telegraf.conf
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_min_incomplete/telegraf.conf
rename to plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_max/telegraf.conf
diff --git a/plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_min_incomplete/expected.err b/plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_min_incomplete/expected.err
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_min_incomplete/expected.err
rename to plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_min_incomplete/expected.err
diff --git a/plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_min_incomplete/expected.out b/plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_min_incomplete/expected.out
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_min_incomplete/expected.out
rename to plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_min_incomplete/expected.out
diff --git a/plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_min_incomplete/input.txt b/plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_min_incomplete/input.txt
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_min_incomplete/input.txt
rename to plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_min_incomplete/input.txt
diff --git a/plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_one_per_packet/telegraf.conf b/plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_min_incomplete/telegraf.conf
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_one_per_packet/telegraf.conf
rename to plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_min_incomplete/telegraf.conf
diff --git a/plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_one_per_packet/expected.out b/plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_one_per_packet/expected.out
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_one_per_packet/expected.out
rename to plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_one_per_packet/expected.out
diff --git a/plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_one_per_packet/input.txt b/plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_one_per_packet/input.txt
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_one_per_packet/input.txt
rename to plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_one_per_packet/input.txt
diff --git a/plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_trim_message/telegraf.conf b/plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_one_per_packet/telegraf.conf
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_trim_message/telegraf.conf
rename to plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_one_per_packet/telegraf.conf
diff --git a/plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_trim_message/expected.out b/plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_trim_message/expected.out
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_trim_message/expected.out
rename to plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_trim_message/expected.out
diff --git a/plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_trim_message/input.txt b/plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_trim_message/input.txt
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_best_effort_udp_trim_message/input.txt
rename to plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_trim_message/input.txt
diff --git a/plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_trim_message/telegraf.conf b/plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_trim_message/telegraf.conf
new file mode 100644
index 000000000..03575cff4
--- /dev/null
+++ b/plugins/inputs/syslog/testcases/rfc5424_best_effort_udp_trim_message/telegraf.conf
@@ -0,0 +1,4 @@
+[[inputs.syslog]]
+  server = "udp://127.0.0.1:0"
+  syslog_standard = "RFC5424"
+  best_effort = true
\ No newline at end of file
diff --git a/plugins/inputs/syslog/testcases/rfc5424_long_appname/expected.out b/plugins/inputs/syslog/testcases/rfc5424_long_appname/expected.out
new file mode 100644
index 000000000..43049dc95
--- /dev/null
+++ b/plugins/inputs/syslog/testcases/rfc5424_long_appname/expected.out
@@ -0,0 +1 @@
+syslog,appname=ALongApplicationNameContainingExactly48Character,facility=local3,hostname=mymachine.example.com,severity=emerg,source=127.0.0.1 facility_code=19i,message="BOM'su root' failed for lonvick on /dev/pts/8",msgid="ID47",severity_code=0i,timestamp=1065910455003000000i,version=1u 1708596139072781296
diff --git a/plugins/inputs/syslog/testcases/rfc5424_long_appname/input.txt b/plugins/inputs/syslog/testcases/rfc5424_long_appname/input.txt
new file mode 100644
index 000000000..1d28e783e
--- /dev/null
+++ b/plugins/inputs/syslog/testcases/rfc5424_long_appname/input.txt
@@ -0,0 +1 @@
+<152>1 2003-10-11T22:14:15.003Z mymachine.example.com ALongApplicationNameContainingExactly48Character - ID47 - BOM'su root' failed for lonvick on /dev/pts/8
diff --git a/plugins/inputs/syslog/testcases/rfc5426_strict_udp/telegraf.conf b/plugins/inputs/syslog/testcases/rfc5424_long_appname/telegraf.conf
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_strict_udp/telegraf.conf
rename to plugins/inputs/syslog/testcases/rfc5424_long_appname/telegraf.conf
diff --git a/plugins/inputs/syslog/testcases/rfc5424_strict_toolong_appname/expected.err b/plugins/inputs/syslog/testcases/rfc5424_strict_toolong_appname/expected.err
new file mode 100644
index 000000000..a7b4e4e3a
--- /dev/null
+++ b/plugins/inputs/syslog/testcases/rfc5424_strict_toolong_appname/expected.err
@@ -0,0 +1 @@
+expecting an app-name (from 1 to max 48 US-ASCII characters) or a nil value
\ No newline at end of file
diff --git a/plugins/inputs/syslog/testcases/rfc5424_strict_toolong_appname/input.txt b/plugins/inputs/syslog/testcases/rfc5424_strict_toolong_appname/input.txt
new file mode 100644
index 000000000..2ed91f0f9
--- /dev/null
+++ b/plugins/inputs/syslog/testcases/rfc5424_strict_toolong_appname/input.txt
@@ -0,0 +1 @@
+<163>1 2003-10-11T22:14:15.003Z mymachine.example.com ALongApplicationNameContainingMoreThanTheAllowed48Character - ID47 - BOM'su root' failed for lonvick on /dev/pts/8
diff --git a/plugins/inputs/syslog/testcases/rfc5426_strict_udp_average/telegraf.conf b/plugins/inputs/syslog/testcases/rfc5424_strict_toolong_appname/telegraf.conf
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_strict_udp_average/telegraf.conf
rename to plugins/inputs/syslog/testcases/rfc5424_strict_toolong_appname/telegraf.conf
diff --git a/plugins/inputs/syslog/testcases/rfc5426_strict_udp/expected.out b/plugins/inputs/syslog/testcases/rfc5424_strict_udp/expected.out
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_strict_udp/expected.out
rename to plugins/inputs/syslog/testcases/rfc5424_strict_udp/expected.out
diff --git a/plugins/inputs/syslog/testcases/rfc5426_strict_udp/input.txt b/plugins/inputs/syslog/testcases/rfc5424_strict_udp/input.txt
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_strict_udp/input.txt
rename to plugins/inputs/syslog/testcases/rfc5424_strict_udp/input.txt
diff --git a/plugins/inputs/syslog/testcases/rfc5426_strict_udp_max/telegraf.conf b/plugins/inputs/syslog/testcases/rfc5424_strict_udp/telegraf.conf
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_strict_udp_max/telegraf.conf
rename to plugins/inputs/syslog/testcases/rfc5424_strict_udp/telegraf.conf
diff --git a/plugins/inputs/syslog/testcases/rfc5426_strict_udp_average/expected.out b/plugins/inputs/syslog/testcases/rfc5424_strict_udp_average/expected.out
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_strict_udp_average/expected.out
rename to plugins/inputs/syslog/testcases/rfc5424_strict_udp_average/expected.out
diff --git a/plugins/inputs/syslog/testcases/rfc5426_strict_udp_average/input.txt b/plugins/inputs/syslog/testcases/rfc5424_strict_udp_average/input.txt
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_strict_udp_average/input.txt
rename to plugins/inputs/syslog/testcases/rfc5424_strict_udp_average/input.txt
diff --git a/plugins/inputs/syslog/testcases/rfc5426_strict_udp_min_incomplete/telegraf.conf b/plugins/inputs/syslog/testcases/rfc5424_strict_udp_average/telegraf.conf
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_strict_udp_min_incomplete/telegraf.conf
rename to plugins/inputs/syslog/testcases/rfc5424_strict_udp_average/telegraf.conf
diff --git a/plugins/inputs/syslog/testcases/rfc5426_strict_udp_max/expected.out b/plugins/inputs/syslog/testcases/rfc5424_strict_udp_max/expected.out
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_strict_udp_max/expected.out
rename to plugins/inputs/syslog/testcases/rfc5424_strict_udp_max/expected.out
diff --git a/plugins/inputs/syslog/testcases/rfc5426_strict_udp_max/input.txt b/plugins/inputs/syslog/testcases/rfc5424_strict_udp_max/input.txt
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_strict_udp_max/input.txt
rename to plugins/inputs/syslog/testcases/rfc5424_strict_udp_max/input.txt
diff --git a/plugins/inputs/syslog/testcases/rfc5426_strict_udp_one_per_packet/telegraf.conf b/plugins/inputs/syslog/testcases/rfc5424_strict_udp_max/telegraf.conf
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_strict_udp_one_per_packet/telegraf.conf
rename to plugins/inputs/syslog/testcases/rfc5424_strict_udp_max/telegraf.conf
diff --git a/plugins/inputs/syslog/testcases/rfc5426_strict_udp_min_incomplete/expected.err b/plugins/inputs/syslog/testcases/rfc5424_strict_udp_min_incomplete/expected.err
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_strict_udp_min_incomplete/expected.err
rename to plugins/inputs/syslog/testcases/rfc5424_strict_udp_min_incomplete/expected.err
diff --git a/plugins/inputs/syslog/testcases/rfc5426_strict_udp_min_incomplete/input.txt b/plugins/inputs/syslog/testcases/rfc5424_strict_udp_min_incomplete/input.txt
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_strict_udp_min_incomplete/input.txt
rename to plugins/inputs/syslog/testcases/rfc5424_strict_udp_min_incomplete/input.txt
diff --git a/plugins/inputs/syslog/testcases/rfc5426_strict_udp_trim_message/telegraf.conf b/plugins/inputs/syslog/testcases/rfc5424_strict_udp_min_incomplete/telegraf.conf
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_strict_udp_trim_message/telegraf.conf
rename to plugins/inputs/syslog/testcases/rfc5424_strict_udp_min_incomplete/telegraf.conf
diff --git a/plugins/inputs/syslog/testcases/rfc5426_strict_udp_one_per_packet/expected.out b/plugins/inputs/syslog/testcases/rfc5424_strict_udp_one_per_packet/expected.out
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_strict_udp_one_per_packet/expected.out
rename to plugins/inputs/syslog/testcases/rfc5424_strict_udp_one_per_packet/expected.out
diff --git a/plugins/inputs/syslog/testcases/rfc5426_strict_udp_one_per_packet/input.txt b/plugins/inputs/syslog/testcases/rfc5424_strict_udp_one_per_packet/input.txt
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_strict_udp_one_per_packet/input.txt
rename to plugins/inputs/syslog/testcases/rfc5424_strict_udp_one_per_packet/input.txt
diff --git a/plugins/inputs/syslog/testcases/rfc5424_strict_udp_one_per_packet/telegraf.conf b/plugins/inputs/syslog/testcases/rfc5424_strict_udp_one_per_packet/telegraf.conf
new file mode 100644
index 000000000..f8cb24155
--- /dev/null
+++ b/plugins/inputs/syslog/testcases/rfc5424_strict_udp_one_per_packet/telegraf.conf
@@ -0,0 +1,3 @@
+[[inputs.syslog]]
+  server = "udp://127.0.0.1:0"
+  syslog_standard = "RFC5424"
\ No newline at end of file
diff --git a/plugins/inputs/syslog/testcases/rfc5426_strict_udp_trim_message/expected.out b/plugins/inputs/syslog/testcases/rfc5424_strict_udp_trim_message/expected.out
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_strict_udp_trim_message/expected.out
rename to plugins/inputs/syslog/testcases/rfc5424_strict_udp_trim_message/expected.out
diff --git a/plugins/inputs/syslog/testcases/rfc5426_strict_udp_trim_message/input.txt b/plugins/inputs/syslog/testcases/rfc5424_strict_udp_trim_message/input.txt
similarity index 100%
rename from plugins/inputs/syslog/testcases/rfc5426_strict_udp_trim_message/input.txt
rename to plugins/inputs/syslog/testcases/rfc5424_strict_udp_trim_message/input.txt
diff --git a/plugins/inputs/syslog/testcases/rfc5424_strict_udp_trim_message/telegraf.conf b/plugins/inputs/syslog/testcases/rfc5424_strict_udp_trim_message/telegraf.conf
new file mode 100644
index 000000000..f8cb24155
--- /dev/null
+++ b/plugins/inputs/syslog/testcases/rfc5424_strict_udp_trim_message/telegraf.conf
@@ -0,0 +1,3 @@
+[[inputs.syslog]]
+  server = "udp://127.0.0.1:0"
+  syslog_standard = "RFC5424"
\ No newline at end of file