diff --git a/config/linkcheckerrc b/config/linkcheckerrc
index 83e11fe0..767556c6 100644
--- a/config/linkcheckerrc
+++ b/config/linkcheckerrc
@@ -212,15 +212,17 @@
 #  ^https?://www\.example\.com/~calvin/ calvin mypass
 #  ^ftp://www\.example\.com/secret/ calvin
 
-# if the website requires a login the URL and optionally the user and
-# password CGI fieldnames can be provided.
+# if the website requires a login via a page with an HTML form the URL of the
+# page and optionally the username and password input element name attributes
+# can be provided.
 #loginurl=http://www.example.com/
 
-# The name of the user and password CGI field
+# The name attributes of the username and password HTML input elements
 #loginuserfield=login
 #loginpasswordfield=password
-# Optionally any additional CGI name/value pairs. Note that the default
-# values are submitted automatically.
+# Optionally the name attributes of any additional input elements and the values
+# to populate them with. Note that these are submitted without checking
+# whether matching input elements exist in the HTML form.
 #loginextrafields=
 #  name1:value1
 #  name 2:value 2
diff --git a/doc/en/linkcheckerrc.5 b/doc/en/linkcheckerrc.5
index 49526789..eee74d1d 100644
--- a/doc/en/linkcheckerrc.5
+++ b/doc/en/linkcheckerrc.5
@@ -1,4 +1,4 @@
-.TH LINKCHECKERRC 5 2020-04-24 "LinkChecker" "LinkChecker User Manual"
+.TH LINKCHECKERRC 5 2020-06-05 "LinkChecker" "LinkChecker User Manual"
 .SH NAME
 linkcheckerrc - configuration file for LinkChecker
 .
@@ -129,35 +129,40 @@ Command line option: \fB\-\-checkextern\fP
 .SS \fB[authentication]\fP
 .TP
 \fBentry=\fP\fIREGEX\fP \fIUSER\fP [\fIPASS\fP] (MULTILINE)
-Provide different user/password pairs for different link types.
-Entries are a triple (URL regex, username, password)
-or a tuple (URL regex, username), where the entries are
-separated by whitespace.
+Provide individual username/password pairs for different links. In addtion to a 
+single login page specified with \fBloginurl\fP multiple FTP,
+HTTP (Basic Authentication) and telnet links are supported. Entries are a
+triple (URL regex, username, password) or a tuple (URL regex, username),
+where the entries are separated by whitespace.
 .br
 The password is optional and if missing it has to be entered at the
 commandline.
 .br
-If the regular expression matches the checked URL, the given user/password
-pair is used for authentication. The commandline options
+If the regular expression matches the checked URL, the given username/password
+pair is used for authentication. The command line options
 \fB\-u\fP and \fB\-p\fP match every link and therefore override the entries
-given here. The first match wins. At the moment, authentication is
-used/needed for http[s] and ftp links.
+given here. The first match wins.
 .br
 Command line option: \fB\-u\fP, \fB\-p\fP
 .TP
 \fBloginurl=\fP\fIURL\fP
-A login URL to be visited before checking. Also needs authentication
-data set for it.
+The URL of a login page to be visited before link checking. The page is expected
+to contain an HTML form to collect credentials and submit them to the address in
+its action attribute using an HTTP POST request.
+The name attributes of the input elements of the form and the values to be
+submitted need to be available (see \fBentry\fP for an explanation of username
+and password values).
 .TP
 \fBloginuserfield=\fP\fISTRING\fP
-The name of the user CGI field. Default name is \fBlogin\fP.
+The name attribute of the username input element. Default: \fBlogin\fP.
 .TP
 \fBloginpasswordfield=\fP\fISTRING\fP
-The name of the password CGI field. Default name is \fBpassword\fP.
+The name attribute of the password input element. Default: \fBpassword\fP.
 .TP
 \fBloginextrafields=\fP\fINAME\fP\fB:\fP\fIVALUE\fP (MULTILINE)
-Optionally any additional CGI name/value pairs. Note that the default
-values are submitted automatically.
+Optionally the name attributes of any additional input elements and the values
+to populate them with. Note that these are submitted without
+checking whether matching input elements exist in the HTML form.
 .SS \fB[output]\fP
 .TP
 \fBdebug=\fP\fISTRING\fP[\fB,\fP\fISTRING\fP...]
diff --git a/doc/web/media/man5/linkcheckerrc.5.html b/doc/web/media/man5/linkcheckerrc.5.html
index 7debade5..72de8e1e 100644
--- a/doc/web/media/man5/linkcheckerrc.5.html
+++ b/doc/web/media/man5/linkcheckerrc.5.html
@@ -146,30 +146,38 @@ The default file location is <b>~/.linkchecker/linkcheckerrc</b> on Unix,
 <h2 class="Ss" id="_fB_authentication__fP"><a class="permalink" href="#_fB_authentication__fP"><b>[authentication]</b></a></h2>
 <dl class="Bl-tag">
   <dt><b>entry=</b><i>REGEX</i> <i>USER</i> [<i>PASS</i>] (MULTILINE)</dt>
-  <dd>Provide different user/password pairs for different link types. Entries
-      are a triple (URL regex, username, password) or a tuple (URL regex,
-      username), where the entries are separated by whitespace.
+  <dd>Provide individual username/password pairs for different links. In addtion
+      to a single login page specified with <b>loginurl</b> multiple FTP, HTTP
+      (Basic Authentication) and telnet links are supported. Entries are a
+      triple (URL regex, username, password) or a tuple (URL regex, username),
+      where the entries are separated by whitespace.
     <br/>
     The password is optional and if missing it has to be entered at the
       commandline.
     <br/>
-    If the regular expression matches the checked URL, the given user/password
-      pair is used for authentication. The commandline options <b>-u</b> and
-      <b>-p</b> match every link and therefore override the entries given here.
-      The first match wins. At the moment, authentication is used/needed for
-      http[s] and ftp links.
+    If the regular expression matches the checked URL, the given
+      username/password pair is used for authentication. The command line
+      options <b>-u</b> and <b>-p</b> match every link and therefore override
+      the entries given here. The first match wins.
     <br/>
     Command line option: <b>-u</b>, <b>-p</b></dd>
   <dt><b>loginurl=</b><i>URL</i></dt>
-  <dd>A login URL to be visited before checking. Also needs authentication data
-      set for it.</dd>
+  <dd>The URL of a login page to be visited before link checking. The page is
+      expected to contain an HTML form to collect credentials and submit them to
+      the address in its action attribute using an HTTP POST request. The name
+      attributes of the input elements of the form and the values to be
+      submitted need to be available (see <b>entry</b> for an explanation of
+      username and password values).</dd>
   <dt><b>loginuserfield=</b><i>STRING</i></dt>
-  <dd>The name of the user CGI field. Default name is <b>login</b>.</dd>
+  <dd>The name attribute of the username input element. Default:
+    <b>login</b>.</dd>
   <dt><b>loginpasswordfield=</b><i>STRING</i></dt>
-  <dd>The name of the password CGI field. Default name is <b>password</b>.</dd>
+  <dd>The name attribute of the password input element. Default:
+      <b>password</b>.</dd>
   <dt><b>loginextrafields=</b><i>NAME</i><b>:</b><i>VALUE</i> (MULTILINE)</dt>
-  <dd>Optionally any additional CGI name/value pairs. Note that the default
-      values are submitted automatically.</dd>
+  <dd>Optionally the name attributes of any additional input elements and the
+      values to populate them with. Note that these are submitted without
+      checking whether matching input elements exist in the HTML form.</dd>
 </dl>
 </section>
 <section class="Ss">
@@ -639,7 +647,7 @@ Copyright &#x00A9; 2000-2014 Bastian Kleineidam
 </div>
 <table class="foot">
   <tr>
-    <td class="foot-date">2020-04-24</td>
+    <td class="foot-date">2020-06-05</td>
     <td class="foot-os">LinkChecker</td>
   </tr>
 </table>
diff --git a/linkcheck/configuration/__init__.py b/linkcheck/configuration/__init__.py
index e4ffd424..b9fffc22 100644
--- a/linkcheck/configuration/__init__.py
+++ b/linkcheck/configuration/__init__.py
@@ -302,12 +302,6 @@ class Configuration(dict):
         """Make login configuration consistent."""
         url = self["loginurl"]
         disable = False
-        if not self["loginpasswordfield"]:
-            log.warn(LOG_CHECK, _("no CGI password fieldname given for login URL."))
-            disable = True
-        if not self["loginuserfield"]:
-            log.warn(LOG_CHECK, _("no CGI user fieldname given for login URL."))
-            disable = True
         if self.get_user_password(url) == (None, None):
             log.warn(
                 LOG_CHECK,
diff --git a/linkcheck/director/__init__.py b/linkcheck/director/__init__.py
index e92e3cc1..342d7652 100644
--- a/linkcheck/director/__init__.py
+++ b/linkcheck/director/__init__.py
@@ -19,7 +19,7 @@ Management of checking a queue of links with several threads.
 import os
 import time
 
-from .. import log, LOG_CHECK, LinkCheckerInterrupt, plugins
+from .. import log, LOG_CHECK, LinkCheckerError, LinkCheckerInterrupt, plugins
 from ..cache import urlqueue, robots_txt, results
 from . import aggregator, console
 
@@ -31,6 +31,9 @@ def check_urls(aggregate):
     """
     try:
         aggregate.visit_loginurl()
+    except LinkCheckerError as msg:
+        log.warn(LOG_CHECK, _("Problem using login URL: %(msg)s.") % dict(msg=msg))
+        return
     except Exception as msg:
         log.warn(LOG_CHECK, _("Error using login URL: %(msg)s.") % dict(msg=msg))
         raise
diff --git a/linkcheck/htmlutil/loginformsearch.py b/linkcheck/htmlutil/loginformsearch.py
index b4db4b67..77103414 100644
--- a/linkcheck/htmlutil/loginformsearch.py
+++ b/linkcheck/htmlutil/loginformsearch.py
@@ -38,8 +38,9 @@ class Form:
 
 
 def search_form(content, cgiuser, cgipassword):
-    """Search for a HTML form in the given HTML content that has the given
-    CGI fields. If no form is found return None.
+    """Search for a HTML form in the given HTML content that has input elements
+    with name attributes that match cgiuser and/or cgipassword. If no such form
+    is found return None.
     """
     soup = htmlsoup.make_soup(content)
     cginames = {cgiuser, cgipassword} - {None}