diff --git a/classes.py b/classes.py
index 681b25d..3ea0669 100644
--- a/classes.py
+++ b/classes.py
@@ -172,6 +172,13 @@ class Irc():
         while True:
             self.aborted.clear()
             self.initVars()
+
+            try:
+                self.proto.validateServerConf()
+            except AssertionError as e:
+                log.exception("(%s) Configuration error: %s", self.name, e)
+                return
+
             ip = self.serverdata["ip"]
             port = self.serverdata["port"]
             checks_ok = True
@@ -1144,6 +1151,18 @@ class Protocol():
         # Lock for updateTS to make sure only one thread can change the channel TS at one time.
         self.ts_lock = threading.Lock()
 
+        # Lists required conf keys for the server block.
+        self.conf_keys = {'ip', 'port', 'hostname', 'sid', 'sidrange', 'protocol', 'sendpass',
+                          'recvpass'}
+
+    def validateServerConf(self):
+        """Validates that the server block given contains the required keys."""
+        for k in self.conf_keys:
+            assert k in self.irc.serverdata, "Missing option %r in server block for network %s." % (k, self.irc.name)
+
+        port = self.irc.serverdata['port']
+        assert type(port) == int and 0 < port < 65535, "Invalid port %r for network %s" % (port, self.irc.name)
+
     def parseArgs(self, args):
         """Parses a string of RFC1459-style arguments split into a list, where ":" may
         be used for multi-word arguments that last until the end of a line.
diff --git a/conf.py b/conf.py
index 37679fd..2ae379f 100644
--- a/conf.py
+++ b/conf.py
@@ -50,10 +50,6 @@ def validateConf(conf):
     for section in ('bot', 'servers', 'login', 'logging'):
         assert conf.get(section), "Missing %r section in config." % section
 
-    for netname, serverblock in conf['servers'].items():
-        for section in ('ip', 'port', 'hostname', 'sid', 'sidrange', 'protocol'):
-            assert serverblock.get(section), "Missing %r in server block for %r." % (section, netname)
-
     assert type(conf['login'].get('password')) == type(conf['login'].get('user')) == str and \
         conf['login']['password'] != "changeme", "You have not set the login details correctly!"
 
diff --git a/protocols/clientbot.py b/protocols/clientbot.py
index 0017626..125ffaf 100644
--- a/protocols/clientbot.py
+++ b/protocols/clientbot.py
@@ -10,6 +10,9 @@ class ClientbotWrapperProtocol(Protocol):
     def __init__(self, irc):
         super().__init__(irc)
 
+        # Remove conf key checks for those not needed for Clientbot.
+        self.conf_keys -= {'recvpass', 'sendpass'}
+
         # This is just a fallback. Actual casemapping is fetched by handle_005()
         self.casemapping = 'ascii'
 
diff --git a/protocols/ircs2s_common.py b/protocols/ircs2s_common.py
index 7f78724..93afdb0 100644
--- a/protocols/ircs2s_common.py
+++ b/protocols/ircs2s_common.py
@@ -39,7 +39,6 @@ class IRCS2SProtocol(Protocol):
 
         return {'target': killed, 'text': killmsg, 'userdata': data}
 
-
     def handle_squit(self, numeric, command, args):
         """Handles incoming SQUITs."""
         return self._squit(numeric, command, args)