fix #2284 (#2317)

Send a configurable NOTICE on first connection that hopm can
detect via target_string

default.yaml

@@ -180,6 +180,10 @@ server:
     # if this is true, the motd is escaped using formatting codes like $c, $b, and $i
     motd-formatting: true
 
+    # send a configurable notice to clients immediately after they connect,
+    # as a way of detecting open proxies
+    #initial-notice: "*** Welcome to the Ergo IRC server"
+
     # idle timeouts for inactive clients
     idle-timeouts:
         # give the client this long to complete connection registration (i.e. the initial

docs/MANUAL.md

@@ -1072,9 +1072,12 @@ You can import user and channel registrations from an Anope or Atheme database i
 
 ## Hybrid Open Proxy Monitor (HOPM)
 
-[hopm](https://github.com/ircd-hybrid/hopm) can be used to monitor your server for connections from open proxies, then automatically ban them. To configure hopm to work with Ergo, add operator blocks like this to your Ergo config file, which grant hopm the necessary privileges:
+[hopm](https://github.com/ircd-hybrid/hopm) can be used to monitor your server for connections from open proxies, then automatically ban them. To configure hopm to work with Ergo, configure `server.initial_notice` and add operator blocks like this to your Ergo config file, which grant hopm the necessary privileges:
 
 ````yaml
+server:
+    initial-notice: "Welcome to the Ergo IRC server"
+
 # operator classes
 oper-classes:
     # hopm
@@ -1109,6 +1112,9 @@ opers:
 Then configure hopm like this:
 
 ````
+/* replace with the exact notice your server sends on first connection */
+target_string = ":ergo.test NOTICE * :*** Welcome to the Ergo IRC server"
+
 /* ergo */
 connregex = ".+-.+CONNECT.+-.+ Client Connected \\[([^ ]+)\\] \\[u:([^ ]+)\\] \\[h:([^ ]+)\\] \\[ip:([^ ]+)\\] .+";
 

irc/client.go

@@ -414,6 +414,11 @@ func (server *Server) RunClient(conn IRCConn) {
 		session.certfp, session.peerCerts, _ = utils.GetCertFP(wConn.Conn, RegisterTimeout)
 	}
 
+	if config.Server.InitialNotice != "" {
+		// send initial notice for HOPM to recognize
+		client.Send(nil, client.server.name, "NOTICE", "*", config.Server.InitialNotice)
+	}
+
 	if session.isTor {
 		session.rawHostname = config.Server.TorListeners.Vhost
 		client.rawHostname = session.rawHostname

irc/config.go

@@ -580,7 +580,8 @@ type Config struct {
 		CoerceIdent             string `yaml:"coerce-ident"`
 		MOTD                    string
 		motdLines               []string
-		MOTDFormatting          bool `yaml:"motd-formatting"`
+		MOTDFormatting          bool   `yaml:"motd-formatting"`
+		InitialNotice           string `yaml:"initial-notice"`
 		IdleTimeouts            struct {
 			Registration time.Duration
 			Ping         time.Duration

traditional.yaml

@@ -154,6 +154,10 @@ server:
     # if this is true, the motd is escaped using formatting codes like $c, $b, and $i
     motd-formatting: true
 
+    # send a configurable notice to clients immediately after they connect,
+    # as a way of detecting open proxies
+    #initial-notice: "*** Welcome to the Ergo IRC server"
+
     # idle timeouts for inactive clients
     idle-timeouts:
         # give the client this long to complete connection registration (i.e. the initial