sysctl retries1 and retries2 are customizable via the interface

luci-app-openmptcprouter/luasrc/controller/openmptcprouter.lua

@@ -741,6 +741,16 @@ function settings_add()
 	luci.sys.exec("sysctl -w net.ipv4.tcp_syn_retries=%s" % tcp_syn_retries)
 	luci.sys.exec("sed -i 's:^net.ipv4.tcp_syn_retries=[0-9]*:net.ipv4.tcp_syn_retries=%s:' /etc/sysctl.d/zzz_openmptcprouter.conf" % tcp_syn_retries)
 
+	-- Set tcp_retries1
+	local tcp_retries1 = luci.http.formvalue("tcp_retries1")
+	luci.sys.exec("sysctl -w net.ipv4.tcp_retries1=%s" % tcp_retries1)
+	luci.sys.exec("sed -i 's:^net.ipv4.tcp_retries1=[0-9]*:net.ipv4.tcp_retries1=%s:' /etc/sysctl.d/zzz_openmptcprouter.conf" % tcp_retries1)
+
+	-- Set tcp_retries2
+	local tcp_retries2 = luci.http.formvalue("tcp_retries2")
+	luci.sys.exec("sysctl -w net.ipv4.tcp_retries2=%s" % tcp_retries2)
+	luci.sys.exec("sed -i 's:^net.ipv4.tcp_retries2=[0-9]*:net.ipv4.tcp_retries2=%s:' /etc/sysctl.d/zzz_openmptcprouter.conf" % tcp_retries2)
+
 	--local tcp_retries2 = luci.http.formvalue("tcp_retries2")
 	--luci.sys.exec("sysctl -w net.ipv4.tcp_retries2=%s" % tcp_retries2)
 	--luci.sys.exec("sed -i 's:^net.ipv4.tcp_retries2=[0-9]*:net.ipv4.tcp_retries2=%s:' /etc/sysctl.d/zzz_openmptcprouter.conf" % tcp_retries2)

luci-app-openmptcprouter/luasrc/view/openmptcprouter/settings.htm

@@ -118,18 +118,50 @@
 	        <label class="cbi-value-title"><%:IPv4 TCP Keepalive time%></label>
 	        <div class="cbi-value-field">
 		    <input type="text" name="tcp_keepalive_time" class="cbi-input-text" value="<%=tonumber((luci.sys.exec("sysctl net.ipv4.tcp_keepalive_time")):match(" %d+"))%>">
+		    <br />
+		    <div class="cbi-value-description">
+			<%:How often TCP sends out keepalive messages when keepalive is enabled.%>
+		    </div>
 		</div>
 	    </div>
 	    <div class="cbi-value">
 	        <label class="cbi-value-title"><%:IPv4 TCP FIN timeout%></label>
 	        <div class="cbi-value-field">
 		    <input type="text" name="tcp_fin_timeout" class="cbi-input-text" value="<%=tonumber((luci.sys.exec("sysctl net.ipv4.tcp_fin_timeout")):match(" %d+"))%>">
+		    <br />
+		    <div class="cbi-value-description">
+			<%:The length of time an orphaned (no longer referenced by any application) connection will remain in the FIN_WAIT_2 state before it is aborted at the local end.%>
+		    </div>
 		</div>
 	    </div>
 	    <div class="cbi-value">
 	        <label class="cbi-value-title"><%:IPv4 TCP SYN retries%></label>
 	        <div class="cbi-value-field">
 		    <input type="text" name="tcp_syn_retries" class="cbi-input-text" value="<%=tonumber((luci.sys.exec("sysctl net.ipv4.tcp_syn_retries")):match(" %d+"))%>">
+		    <br />
+		    <div class="cbi-value-description">
+			<%:Number of times initial SYNs for an active TCP connection attempt will be retransmitted.%>
+		    </div>
+		</div>
+	    </div>
+	    <div class="cbi-value">
+	        <label class="cbi-value-title"><%:IPv4 TCP SYN retries1%></label>
+	        <div class="cbi-value-field">
+		    <input type="text" name="tcp_retries1" class="cbi-input-text" value="<%=tonumber((luci.sys.exec("sysctl net.ipv4.tcp_retries1")):match(" %d+"))%>">
+		    <br />
+		    <div class="cbi-value-description">
+			<%:This value influences the time, after which TCP decides, that something is wrong due to unacknowledged RTO retransmissions, and reports this suspicion to the network layer.%>
+		    </div>
+		</div>
+	    </div>
+	    <div class="cbi-value">
+	        <label class="cbi-value-title"><%:IPv4 TCP SYN retries2%></label>
+	        <div class="cbi-value-field">
+		    <input type="text" name="tcp_retries2" class="cbi-input-text" value="<%=tonumber((luci.sys.exec("sysctl net.ipv4.tcp_retries2")):match(" %d+"))%>">
+		    <br />
+		    <div class="cbi-value-description">
+			<%:This value influences the timeout of an alive TCP connection, when RTO retransmissions remain unacknowledged.%>
+		    </div>
 		</div>
 	    </div>
 	    <div class="cbi-value">

luci-app-openmptcprouter/root/etc/init.d/openmptcprouter

@@ -83,8 +83,8 @@ start_service() {
 		}
 	}
 	# remove sysctl already defined in /etc/sysctl.d/
-	sed -i -e '/tcp_fin_timeout/d' -e '/tcp_keepalive_time/d' -e '/nf_conntrack_max/d' -e '/tcp_syn_retries/d' -e '/tcp_fastopen/d' -e '/tcp_retries2/d' /etc/sysctl.conf
+	sed -i -e '/tcp_fin_timeout/d' -e '/tcp_keepalive_time/d' -e '/nf_conntrack_max/d' -e '/tcp_syn_retries/d' -e '/tcp_fastopen/d' -e '/tcp_retries2/d' -e '/tcp_retries1/d' /etc/sysctl.conf
-	sed -i -e '/tcp_fin_timeout/d' -e '/tcp_keepalive_time/d' -e '/nf_conntrack_max/d' -e '/tcp_syn_retries/d' -e '/tcp_fastopen/d' -e '/tcp_retries2/d' /etc/sysctl.d/10-default.conf
+	sed -i -e '/tcp_fin_timeout/d' -e '/tcp_keepalive_time/d' -e '/nf_conntrack_max/d' -e '/tcp_syn_retries/d' -e '/tcp_fastopen/d' -e '/tcp_retries2/d' -e '/tcp_retries1/d' /etc/sysctl.d/10-default.conf
 }
 
 reload_service() {

luci-app-openmptcprouter/root/etc/sysctl.d/zzz_openmptcprouter.conf

@@ -2,6 +2,7 @@ net.ipv4.tcp_keepalive_time=7200
 net.ipv6.conf.all.disable_ipv6=0
 net.ipv4.tcp_fin_timeout=60
 net.ipv4.tcp_syn_retries=3
-net.ipv4.tcp_retries2=3
+net.ipv4.tcp_retries1=3
+net.ipv4.tcp_retries2=15
 net.ipv4.tcp_fastopen=3
 net.ipv4.tcp_low_latency=1