From 974a2520586b808e1e1b878b6ae9a1822d3c0f77 Mon Sep 17 00:00:00 2001
From: Hippolyte Chauvin <hchauvin38@outlook.fr>
Date: Fri, 5 May 2023 20:10:39 +0200
Subject: [PATCH] =?UTF-8?q?V=C3=A9rifier=20si=20le=20port=20est=20libre=20?=
 =?UTF-8?q?avant=20de=20faire=20une=20connection=20SSH?=
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---
 bin/ssh-fwd | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/bin/ssh-fwd b/bin/ssh-fwd
index 465a704..9d5c356 100755
--- a/bin/ssh-fwd
+++ b/bin/ssh-fwd
@@ -14,11 +14,17 @@ Usage: $(basename "$0") SSH_HOST LOCAL_PORT DISTANT_PORT [TARGET] [-- SSH_OPTION
 EOF
 }
 
+# Show an error
 function error {
     >&2 usage
     exit "${1:-1}"
 }
 
+# Check if TCP port number is free
+port_is_free() {
+    ! lsof -i -P -n | grep -q ':'"${1}"' (LISTEN)'
+}
+
 # Arguments
 while [[ -n $* ]]; do
     case "$1" in
@@ -54,5 +60,9 @@ ssh_com=(
 
 # Execution
 set -x
-"${ssh_com[@]}"
+if port_is_free "${args[1]}"; then
+    "${ssh_com[@]}"
+else
+    echo "Port is not free, skipping."
+fi