diff --git a/src/channels.rs b/src/channels.rs
index cfe42ae..a2101b5 100644
--- a/src/channels.rs
+++ b/src/channels.rs
@@ -1047,10 +1047,18 @@ impl Server {
                 names.push(' ');
             }
         }
+        // visibility symbol: @ secret (+s), * private (+p), = public
+        let vis = if ch.modes.secret {
+            '@'
+        } else if ch.modes.private {
+            '*'
+        } else {
+            '='
+        };
         self.numeric(
             uid,
             RPL_NAMREPLY,
-            &format!("= {} :{}", ch.name, names.trim_end()),
+            &format!("{vis} {} :{}", ch.name, names.trim_end()),
         );
         self.numeric(
             uid,
@@ -1179,6 +1187,7 @@ impl Server {
     /// +j: record a join attempt on `key`; true if joins are (now) locked out.
     pub fn joinflood_check(&mut self, key: &str) -> bool {
         let n = now();
+        let dur = self.conf_num("joinflood_duration", 60u64);
         let Some(ch) = self.channels.get_mut(key) else {
             return false;
         };
@@ -1191,7 +1200,7 @@ impl Server {
         ch.joinflood_hits.retain(|&t| n.saturating_sub(t) < f.secs);
         ch.joinflood_hits.push(n);
         if ch.joinflood_hits.len() as u32 > f.count {
-            ch.joinflood_until = n + 60; // lock the channel for 60s
+            ch.joinflood_until = n + dur; // lock joins for the configured window
             ch.joinflood_hits.clear();
             return true;
         }
@@ -1202,6 +1211,7 @@ impl Server {
     /// is (now) locked out — the caller denies the change if so. Opers exempt.
     pub fn nickflood_blocked(&mut self, uid: Uid) -> Option<String> {
         let n = now();
+        let dur = self.conf_num("nickflood_duration", 60u64);
         let keys: Vec<String> = self
             .users
             .get(&uid)
@@ -1222,7 +1232,7 @@ impl Server {
             ch.nickflood_hits.retain(|&t| n.saturating_sub(t) < f.secs);
             ch.nickflood_hits.push(n);
             if ch.nickflood_hits.len() as u32 > f.count {
-                ch.nickflood_until = n + 60;
+                ch.nickflood_until = n + dur;
                 ch.nickflood_hits.clear();
                 blocked.get_or_insert_with(|| ch.name.clone());
             }
diff --git a/src/coremods/core_info.rs b/src/coremods/core_info.rs
index 703aee4..4ce88db 100644
--- a/src/coremods/core_info.rs
+++ b/src/coremods/core_info.rs
@@ -224,13 +224,28 @@ impl Command for Whois {
         };
         let chans: Vec<String> = keys
             .iter()
-            .filter_map(|k| s.channels.get(k).map(|c| c.name.clone()))
+            .filter_map(|k| s.channels.get(k))
+            .filter(|c| {
+                // a +s/+p channel is shown only to the target itself, an oper, or a
+                // fellow member — never leaked to an outside asker.
+                is_self
+                    || asker_oper
+                    || (!c.modes.secret && !c.modes.private)
+                    || c.members.contains_key(&uid)
+            })
+            .map(|c| {
+                let pfx = c.members.get(&tuid).map(|m| m.prefix_char()).unwrap_or("");
+                format!("{pfx}{}", c.name)
+            })
             .collect();
         s.numeric(
             uid,
             RPL_WHOISUSER,
             &format!("{nick} {ident} {disp} * :{realname}"),
         );
+        if let Some(away) = s.users.get(&tuid).and_then(|u| u.flags.away.clone()) {
+            s.numeric(uid, RPL_AWAY, &format!("{nick} :{away}"));
+        }
         if bot {
             s.numeric(uid, RPL_WHOISBOT, &format!("{nick} :is a bot"));
         }
@@ -434,7 +449,20 @@ impl Command for Who {
                 None => Vec::new(),
             }
         } else if let Some(tuid) = s.find_nick(target) {
-            vec![(tuid, "*".to_string(), String::new())]
+            // hide a +i (invisible) user from a WHO by someone who shares no channel
+            // with them (self and opers always see them).
+            let hidden = s.users.get(&tuid).map(|u| u.flags.invisible).unwrap_or(false)
+                && tuid != uid
+                && !asker_oper
+                && !s
+                    .channels
+                    .values()
+                    .any(|c| c.members.contains_key(&uid) && c.members.contains_key(&tuid));
+            if hidden {
+                Vec::new()
+            } else {
+                vec![(tuid, "*".to_string(), String::new())]
+            }
         } else {
             Vec::new()
         };
diff --git a/src/coremods/core_message.rs b/src/coremods/core_message.rs
index 1674e29..4643d7b 100644
--- a/src/coremods/core_message.rs
+++ b/src/coremods/core_message.rs
@@ -161,20 +161,29 @@ pub(crate) fn deliver(s: &mut Server, uid: Uid, params: &[String], notice: bool)
     };
     if target.starts_with('#') {
         let key = target.to_ascii_lowercase();
-        let member = s
+        let (member, no_external) = s
             .channels
             .get(&key)
-            .map(|c| c.members.contains_key(&uid))
-            .unwrap_or(false);
+            .map(|c| (c.members.contains_key(&uid), c.modes.no_external))
+            .unwrap_or((false, true));
         if !member {
-            if !notice {
-                s.numeric(
-                    uid,
-                    ERR_CANNOTSENDTOCHAN,
-                    &format!("{target} :Cannot send to channel"),
-                );
+            // +n (default): only members may message the channel. With -n an external
+            // user may — unless banned (+b, not +e-excepted), so -n can't evade a ban.
+            let banned = s
+                .channels
+                .get(&key)
+                .map(|c| s.ban_list_hit(uid, &c.bans) && !s.ban_list_hit(uid, &c.excepts))
+                .unwrap_or(true);
+            if no_external || banned {
+                if !notice {
+                    s.numeric(
+                        uid,
+                        ERR_CANNOTSENDTOCHAN,
+                        &format!("{target} :Cannot send to channel"),
+                    );
+                }
+                return CmdResult::Fail;
             }
-            return CmdResult::Fail;
         }
         // +U opmoderated — an unprivileged user's message isn't blocked; it's routed
         // to channel ops only (below). It also overrides +m's block for that purpose.
diff --git a/src/mode.rs b/src/mode.rs
index 8a551d8..a306683 100644
--- a/src/mode.rs
+++ b/src/mode.rs
@@ -499,7 +499,9 @@ impl ChanMode for Key {
         param: Option<&str>,
     ) -> Applied {
         if adding {
-            let Some(k) = param else {
+            // a key is one non-empty token: reject space/comma/':'/empty, else the
+            // MODE/FMODE wire line splits and peers parse only the first word.
+            let Some(k) = param.filter(|k| !k.is_empty() && !k.contains([' ', ',', ':'])) else {
                 return Applied::No;
             };
             if let Some(c) = s.channels.get_mut(key) {
@@ -536,7 +538,8 @@ impl ChanMode for Limit {
         param: Option<&str>,
     ) -> Applied {
         if adding {
-            let Some(n) = param.and_then(|p| p.parse::<u32>().ok()) else {
+            // reject +l 0 and non-numeric: a zero limit would seal the channel.
+            let Some(n) = param.and_then(|p| p.parse::<u32>().ok()).filter(|&n| n > 0) else {
                 return Applied::No;
             };
             if let Some(c) = s.channels.get_mut(key) {
@@ -763,17 +766,31 @@ impl ChanMode for ListMode {
                 .get(&uid)
                 .map(|u| u.nick.clone())
                 .unwrap_or_default();
+            let sudo = s.mode_sudo;
+            let maxlist = s.conf_num("maxbans", 100usize);
+            let mut full = false;
             if let Some(c) = s.channels.get_mut(key) {
                 let list = self.kind.list_mut(c);
-                if list.iter().any(|b| b.mask == mask) {
+                // dedup case-insensitively: glob_match lowercases at match time, so
+                // `*!*@Host` and `*!*@host` catch the same users — store only one.
+                if list.iter().any(|b| b.mask.eq_ignore_ascii_case(&mask)) {
                     return Applied::No; // already present
                 }
-                list.push(Ban {
-                    mask: mask.clone(),
-                    setter,
-                    ts: now(),
-                    expires: None,
-                });
+                // cap the list for local users; a burst / services set bypasses it.
+                if !sudo && list.len() >= maxlist {
+                    full = true;
+                } else {
+                    list.push(Ban {
+                        mask: mask.clone(),
+                        setter,
+                        ts: now(),
+                        expires: None,
+                    });
+                }
+            }
+            if full {
+                s.numeric(uid, ERR_BANLISTFULL, &format!("{chan} {mask} :Channel list is full"));
+                return Applied::No;
             }
             Applied::Yes(Some(mask))
         } else {
@@ -781,7 +798,7 @@ impl ChanMode for ListMode {
             if let Some(c) = s.channels.get_mut(key) {
                 let list = self.kind.list_mut(c);
                 let before = list.len();
-                list.retain(|b| b.mask != mask);
+                list.retain(|b| !b.mask.eq_ignore_ascii_case(&mask));
                 removed = list.len() < before;
             }
             if removed {
diff --git a/src/numeric.rs b/src/numeric.rs
index ddd22d4..5a5eccc 100644
--- a/src/numeric.rs
+++ b/src/numeric.rs
@@ -139,6 +139,7 @@ pub const ERR_CHANNELISFULL: u16 = 471;
 pub const ERR_UNKNOWNMODE: u16 = 472;
 pub const ERR_INVITEONLYCHAN: u16 = 473;
 pub const ERR_BADCHANNELKEY: u16 = 475;
+pub const ERR_BANLISTFULL: u16 = 478; // +b/+e/+I list at its per-channel cap
 pub const ERR_CHANOPRIVSNEEDED: u16 = 482;
 pub const ERR_SECUREONLYCHAN: u16 = 489; // can't join a +z channel without TLS
 pub const ERR_ALLMUSTSSL: u16 = 490; // can't set +z while a member isn't on TLS