diff --git a/src/os.c b/src/os.c
index d5e4482..ee525aa 100644
--- a/src/os.c
+++ b/src/os.c
@@ -445,20 +445,25 @@ Cmds firewall_rules_cmds(int is_server)
 #ifdef __linux__
         static const char
             *set_cmds[] =
-                { "sysctl net.ipv4.ip_forward=1",
-                  "ip addr add $LOCAL_TUN_IP peer $REMOTE_TUN_IP dev $IF_NAME",
+                { "ip addr add $LOCAL_TUN_IP peer $REMOTE_TUN_IP dev $IF_NAME",
                   "ip -6 addr add $LOCAL_TUN_IP6 peer $REMOTE_TUN_IP6/96 dev $IF_NAME",
                   "ip link set dev $IF_NAME up",
+#ifndef NO_DEFAULT_FIREWALL
+                  "sysctl net.ipv4.ip_forward=1",
                   "iptables -t nat -A POSTROUTING -o $EXT_IF_NAME -s $REMOTE_TUN_IP -j MASQUERADE",
                   "iptables -t filter -A FORWARD -i $EXT_IF_NAME -o $IF_NAME -m state --state "
                   "RELATED,ESTABLISHED -j ACCEPT",
                   "iptables -t filter -A FORWARD -i $IF_NAME -o $EXT_IF_NAME -j ACCEPT",
+#endif
                   NULL },
             *unset_cmds[] = {
+#ifndef NO_DEFAULT_FIREWALL
                 "iptables -t nat -D POSTROUTING -o $EXT_IF_NAME -s $REMOTE_TUN_IP -j MASQUERADE",
                 "iptables -t filter -D FORWARD -i $EXT_IF_NAME -o $IF_NAME -m state --state "
                 "RELATED,ESTABLISHED -j ACCEPT",
-                "iptables -t filter -D FORWARD -i $IF_NAME -o $EXT_IF_NAME -j ACCEPT", NULL
+                "iptables -t filter -D FORWARD -i $IF_NAME -o $EXT_IF_NAME -j ACCEPT", 
+#endif
+                NULL
             };
 #elif defined(__APPLE__) || defined(__OpenBSD__) || defined(__FreeBSD__) || \
     defined(__DragonFly__) || defined(__NetBSD__)
@@ -492,7 +497,10 @@ Cmds firewall_rules_cmds(int is_server)
                           };
 #elif defined(__linux__)
         static const char
-            *set_cmds[]   = { "sysctl net.ipv4.tcp_congestion_control=bbr",
+            *set_cmds[]   = {
+#ifndef NO_DEFAULT_CONGESTION
+                            "sysctl net.ipv4.tcp_congestion_control=bbr",
+#endif
                             "ip link set dev $IF_NAME up",
                             "ip addr add $LOCAL_TUN_IP peer $REMOTE_TUN_IP dev $IF_NAME",
                             "ip -6 addr add $LOCAL_TUN_IP6 peer $REMOTE_TUN_IP6/96 dev $IF_NAME",
@@ -505,9 +513,13 @@ Cmds firewall_rules_cmds(int is_server)
                             "ip -6 rule add table main suppress_prefixlength 0",
 #endif
                             NULL },
-            *unset_cmds[] = { "ip rule delete table 42069", "ip -6 rule delete table 42069",
+            *unset_cmds[] = { 
+#ifndef NO_DEFAULT_ROUTES
+                              "ip rule delete table 42069", "ip -6 rule delete table 42069",
                               "ip rule delete table main suppress_prefixlength 0",
-                              "ip -6 rule delete table main suppress_prefixlength 0", NULL };
+                              "ip -6 rule delete table main suppress_prefixlength 0",
+#endif
+                               NULL };
 #else
         static const char *const *set_cmds = NULL, *const *unset_cmds = NULL;
 #endif