fix: remove comments

- Set DNS resolvers via systemd-resolved after flushDns on connect (vpnConnection.cpp)
- RevertLink after systemd-resolved restart on disconnect (DnsUtilsLinux)
- Add scheduleRetry() to retry full DNS setup on D-Bus transient failures
- Reduce D-Bus call timeout to 5s; use systemctl restart for flushDns
- Guard maybeUpdateResolvers with #ifndef Q_OS_LINUX to preserve macOS/Windows DNS

client/core/utils/networkUtilities.cpp

@@ -286,7 +286,7 @@ QPair<QString, QNetworkInterface> NetworkUtilities::getGatewayAndIface()
     return { resGateway, QNetworkInterface::interfaceFromIndex(resIndex) };
 #endif
 #ifdef Q_OS_LINUX
-    constexpr int BUFFER_SIZE = 100;
+    constexpr int BUFFER_SIZE = 8192;
     int     received_bytes = 0, msg_len = 0, route_attribute_len = 0;
     int     sock = -1, msgseq = 0;
     struct  nlmsghdr *nlh, *nlmsg;
@@ -294,7 +294,7 @@ QPair<QString, QNetworkInterface> NetworkUtilities::getGatewayAndIface()
     // This struct contain route attributes (route type)
     struct  rtattr *route_attribute;
     char    gateway_address[INET_ADDRSTRLEN], interface[IF_NAMESIZE];
-    char    msgbuf[BUFFER_SIZE], buffer[BUFFER_SIZE];
+    char    msgbuf[100], buffer[BUFFER_SIZE];
     char    *ptr = buffer;
     struct timeval tv;
 
@@ -339,8 +339,8 @@ QPair<QString, QNetworkInterface> NetworkUtilities::getGatewayAndIface()
         nlh = (struct nlmsghdr *) ptr;
 
         /* Check if the header is valid */
-        if((NLMSG_OK(nlmsg, received_bytes) == 0) ||
+        if((NLMSG_OK(nlh, received_bytes) == 0) ||
-            (nlmsg->nlmsg_type == NLMSG_ERROR))
+            (nlh->nlmsg_type == NLMSG_ERROR))
         {
             perror("Error in received packet");
             return {};
@@ -355,13 +355,15 @@ QPair<QString, QNetworkInterface> NetworkUtilities::getGatewayAndIface()
         }
 
         /* Break if its not a multi part message */
-        if ((nlmsg->nlmsg_flags & NLM_F_MULTI) == 0)
+        if ((nlh->nlmsg_flags & NLM_F_MULTI) == 0)
             break;
     }
-    while ((nlmsg->nlmsg_seq != msgseq) || (nlmsg->nlmsg_pid != getpid()));
+    while ((nlh->nlmsg_seq != msgseq) || (nlh->nlmsg_pid != getpid()));
 
     /* parse response */
-    for ( ; NLMSG_OK(nlh, received_bytes); nlh = NLMSG_NEXT(nlh, received_bytes))
+    int remaining = msg_len + received_bytes;
+    nlh = (struct nlmsghdr *) buffer;
+    for ( ; NLMSG_OK(nlh, remaining); nlh = NLMSG_NEXT(nlh, remaining))
     {
         /* Get the route data */
         route_entry = (struct rtmsg *) NLMSG_DATA(nlh);
@@ -370,6 +372,10 @@ QPair<QString, QNetworkInterface> NetworkUtilities::getGatewayAndIface()
         if (route_entry->rtm_table != RT_TABLE_MAIN)
             continue;
 
+        /* Reset per-route to avoid cross-route state pollution */
+        memset(gateway_address, 0, sizeof(gateway_address));
+        memset(interface, 0, sizeof(interface));
+
         route_attribute = (struct rtattr *) RTM_RTA(route_entry);
         route_attribute_len = RTM_PAYLOAD(nlh);
 
@@ -395,6 +401,8 @@ QPair<QString, QNetworkInterface> NetworkUtilities::getGatewayAndIface()
             break;
         }
     }
+    if (!(*gateway_address) || !(*interface))
+        qDebug() << "getGatewayAndIface: no gateway found";
     close(sock);
     return { gateway_address, QNetworkInterface::interfaceFromName(interface) };
 #endif

client/daemon/daemon.cpp

@@ -78,14 +78,6 @@ bool Daemon::activate(const InterfaceConfig& config) {
         return false;
       }
 
-      if (!dnsutils()->restoreResolvers()) {
-        return false;
-      }
-
-      if (!maybeUpdateResolvers(config)) {
-        return false;
-      }
-
       bool status = run(Switch, config);
       logger.debug() << "Connection status:" << status;
       if (status) {
@@ -142,10 +134,6 @@ bool Daemon::activate(const InterfaceConfig& config) {
     return false;
   }
 
-  if (!maybeUpdateResolvers(config)) {
-    return false;
-  }
-
   // set routing
   for (const IPAddress& ip : config.m_allowedIPAddressRanges) {
     if (!wgutils()->updateRoutePrefix(ip)) {
@@ -154,6 +142,12 @@ bool Daemon::activate(const InterfaceConfig& config) {
     }
   }
 
+#ifndef Q_OS_LINUX
+  if (!maybeUpdateResolvers(config)) {
+    return false;
+  }
+#endif
+
   bool status = run(Up, config);
   logger.debug() << "Connection status:" << status;
   if (status) {
@@ -168,15 +162,20 @@ bool Daemon::activate(const InterfaceConfig& config) {
 bool Daemon::maybeUpdateResolvers(const InterfaceConfig& config) {
   if ((config.m_hopType == InterfaceConfig::MultiHopExit) ||
       (config.m_hopType == InterfaceConfig::SingleHop)) {
+    if (!dnsutils()) {
+      logger.error() << "dnsutils is null, cannot update resolvers";
+      return false;
+    }
+
     QList<QHostAddress> resolvers;
     resolvers.append(QHostAddress(config.m_primaryDnsServer));
     if (!config.m_secondaryDnsServer.isEmpty()) {
         resolvers.append(QHostAddress(config.m_secondaryDnsServer));
     }
 
-    // If the DNS is not the Gateway, it's a user defined DNS
+    // If the DNS is the Gateway, also add IPv6 gateway (only if non-empty)
-    // thus, not add any other :)
+    if (config.m_primaryDnsServer == config.m_serverIpv4Gateway &&
-    if (config.m_primaryDnsServer == config.m_serverIpv4Gateway) {
+        !config.m_serverIpv6Gateway.isEmpty()) {
       resolvers.append(QHostAddress(config.m_serverIpv6Gateway));
     }
 

client/platforms/linux/daemon/dnsutilslinux.cpp

@@ -7,8 +7,11 @@
 #include <net/if.h>
 
 #include <QDBusVariant>
+#include <QNetworkInterface>
+#include <QTimer>
 #include <QtDBus/QtDBus>
 
+#include "core/utils/networkUtilities.h"
 #include "leakdetector.h"
 #include "logger.h"
 
@@ -27,24 +30,78 @@ DnsUtilsLinux::DnsUtilsLinux(QObject* parent) : DnsUtils(parent) {
   logger.debug() << "DnsUtilsLinux created.";
 
   QDBusConnection conn = QDBusConnection::systemBus();
-  m_resolver = new QDBusInterface(DBUS_RESOLVE_SERVICE, DBUS_RESOLVE_PATH,
+  auto* watcher = new QDBusServiceWatcher(
-                                  DBUS_RESOLVE_MANAGER, conn, this);
+      DBUS_RESOLVE_SERVICE, conn,
+      QDBusServiceWatcher::WatchForRegistration |
+      QDBusServiceWatcher::WatchForUnregistration, this);
+
+  connect(watcher, &QDBusServiceWatcher::serviceRegistered,
+          this, &DnsUtilsLinux::onResolverRegistered);
+  connect(watcher, &QDBusServiceWatcher::serviceUnregistered,
+          this, &DnsUtilsLinux::onResolverUnregistered);
+
+  if (conn.interface()->isServiceRegistered(DBUS_RESOLVE_SERVICE)) {
+    onResolverRegistered();
+  }
+}
+
+void DnsUtilsLinux::onResolverRegistered() {
+  m_resolver.reset(new QDBusInterface(DBUS_RESOLVE_SERVICE, DBUS_RESOLVE_PATH,
+                                      DBUS_RESOLVE_MANAGER,
+                                      QDBusConnection::systemBus()));
+  logger.debug() << "systemd-resolved available, DNS resolver initialized";
+
+  if (m_revertAfterRegister > 0) {
+    logger.debug() << "Calling RevertLink after restart for ifindex" << m_revertAfterRegister;
+    QDBusMessage msg = QDBusMessage::createMethodCall(
+        DBUS_RESOLVE_SERVICE, DBUS_RESOLVE_PATH, DBUS_RESOLVE_MANAGER, "RevertLink");
+    msg.setArguments({QVariant::fromValue(m_revertAfterRegister)});
+    QDBusPendingReply<> reply = QDBusConnection::systemBus().asyncCall(msg, 5000);
+    int savedIdx = m_revertAfterRegister;
+    m_revertAfterRegister = 0;
+    QDBusPendingCallWatcher* watcher = new QDBusPendingCallWatcher(reply, this);
+    QObject::connect(watcher, &QDBusPendingCallWatcher::finished, this,
+                     [this, savedIdx](QDBusPendingCallWatcher* w) {
+                       QDBusPendingReply<> r = *w;
+                       if (r.isError()) {
+                         logger.debug() << "RevertLink after restart failed for ifindex" << savedIdx
+                                        << ":" << r.error().message();
+                       } else {
+                         logger.debug() << "RevertLink after restart succeeded for ifindex" << savedIdx;
+                       }
+                       w->deleteLater();
+                     });
+  }
+
+  if (!m_pendingIfname.isEmpty()) {
+    logger.debug() << "Re-applying DNS configuration for" << m_pendingIfname;
+    updateResolvers(m_pendingIfname, m_pendingResolvers);
+  }
+}
+
+void DnsUtilsLinux::onResolverUnregistered() {
+  logger.debug() << "systemd-resolved disappeared, dropping DNS resolver";
+  m_resolver.reset();
 }
 
 DnsUtilsLinux::~DnsUtilsLinux() {
   MZ_COUNT_DTOR(DnsUtilsLinux);
 
-  for (auto iterator = m_linkDomains.constBegin();
+  if (m_revertOnDestroy && m_resolver) {
-       iterator != m_linkDomains.constEnd(); ++iterator) {
+    if (m_gatewayIfindex > 0)
-    QList<QVariant> argumentList;
+      setLinkDefaultRoute(m_gatewayIfindex, true);
-    argumentList << QVariant::fromValue(iterator.key());
-    argumentList << QVariant::fromValue(iterator.value());
-    m_resolver->asyncCallWithArgumentList(QStringLiteral("SetLinkDomains"),
-                                          argumentList);
-  }
 
-  if (m_ifindex > 0) {
+    for (auto iterator = m_linkDomains.constBegin();
-    m_resolver->asyncCall(QStringLiteral("RevertLink"), m_ifindex);
+         iterator != m_linkDomains.constEnd(); ++iterator) {
+      QList<QVariant> argumentList;
+      argumentList << QVariant::fromValue(iterator.key());
+      argumentList << QVariant::fromValue(iterator.value());
+      m_resolver->asyncCallWithArgumentList(QStringLiteral("SetLinkDomains"),
+                                            argumentList);
+    }
+    if (m_ifindex > 0) {
+      m_resolver->asyncCall(QStringLiteral("RevertLink"), m_ifindex);
+    }
   }
 
   logger.debug() << "DnsUtilsLinux destroyed.";
@@ -52,12 +109,37 @@ DnsUtilsLinux::~DnsUtilsLinux() {
 
 bool DnsUtilsLinux::updateResolvers(const QString& ifname,
                                     const QList<QHostAddress>& resolvers) {
+  m_revertAfterRegister = 0;
+
+  if (m_gatewayIfindex > 0) {
+    setLinkDefaultRoute(m_gatewayIfindex, true);
+    m_gatewayIfindex = 0;
+  }
+
   m_ifindex = if_nametoindex(qPrintable(ifname));
   if (m_ifindex <= 0) {
     logger.error() << "Unable to resolve ifindex for" << ifname;
     return false;
   }
 
+  // Reset retry counter only when called externally (not from scheduleRetry)
+  if (ifname != m_pendingIfname || resolvers != m_pendingResolvers)
+    m_domainRetries = 0;
+
+  m_pendingIfname = ifname;
+  m_pendingResolvers = resolvers;
+
+  if (!m_resolver) {
+    logger.debug() << "systemd-resolved not ready, queuing DNS configuration";
+    return true;
+  }
+
+  const int gwIdx = NetworkUtilities::getGatewayAndIface().second.index();
+  if (gwIdx > 0 && gwIdx != m_ifindex && gwIdx != m_gatewayIfindex) {
+    m_gatewayIfindex = gwIdx;
+    setLinkDefaultRoute(gwIdx, false);
+  }
+
   setLinkDNS(m_ifindex, resolvers);
   setLinkDefaultRoute(m_ifindex, true);
   updateLinkDomains();
@@ -65,38 +147,54 @@ bool DnsUtilsLinux::updateResolvers(const QString& ifname,
 }
 
 bool DnsUtilsLinux::restoreResolvers() {
+  m_revertOnDestroy = true;
+  m_pendingIfname.clear();
+  m_pendingResolvers.clear();
+
+  if (m_gatewayIfindex > 0) {
+    setLinkDefaultRoute(m_gatewayIfindex, true);
+    m_gatewayIfindex = 0;
+  }
+
   for (auto iterator = m_linkDomains.constBegin();
        iterator != m_linkDomains.constEnd(); ++iterator) {
     setLinkDomains(iterator.key(), iterator.value());
   }
   m_linkDomains.clear();
 
-  /* Revert the VPN interface's DNS configuration */
   if (m_ifindex > 0) {
-    QList<QVariant> argumentList = {QVariant::fromValue(m_ifindex)};
+    m_revertAfterRegister = m_ifindex;
-    QDBusPendingReply<> reply = m_resolver->asyncCallWithArgumentList(
-        QStringLiteral("RevertLink"), argumentList);
-
-    QDBusPendingCallWatcher* watcher = new QDBusPendingCallWatcher(reply, this);
-    QObject::connect(watcher, SIGNAL(finished(QDBusPendingCallWatcher*)), this,
-                     SLOT(dnsCallCompleted(QDBusPendingCallWatcher*)));
-
     m_ifindex = 0;
   }
 
   return true;
 }
 
+void DnsUtilsLinux::scheduleRetry() {
+  if (m_pendingIfname.isEmpty() || m_retryPending || m_domainRetries >= 5)
+    return;
+  m_retryPending = true;
+  ++m_domainRetries;
+  logger.debug() << "Retrying full DNS setup (" << m_domainRetries << "/5)";
+  QTimer::singleShot(1000, this, [this]() {
+    m_retryPending = false;
+    if (!m_pendingIfname.isEmpty())
+      updateResolvers(m_pendingIfname, m_pendingResolvers);
+  });
+}
+
 void DnsUtilsLinux::dnsCallCompleted(QDBusPendingCallWatcher* call) {
   QDBusPendingReply<> reply = *call;
   if (reply.isError()) {
-    logger.error() << "Error received from the DBus service";
+    logger.debug() << "DBus call failed (may be transient after systemd-resolved restart)";
+    scheduleRetry();
   }
   delete call;
 }
 
 void DnsUtilsLinux::setLinkDNS(int ifindex,
                                const QList<QHostAddress>& resolvers) {
+  if (!m_resolver) return;
   QList<DnsResolver> resolverList;
   char ifnamebuf[IF_NAMESIZE];
   const char* ifname = if_indextoname(ifindex, ifnamebuf);
@@ -111,8 +209,10 @@ void DnsUtilsLinux::setLinkDNS(int ifindex,
   QList<QVariant> argumentList;
   argumentList << QVariant::fromValue(ifindex);
   argumentList << QVariant::fromValue(resolverList);
-  QDBusPendingReply<> reply = m_resolver->asyncCallWithArgumentList(
+  QDBusMessage msg = QDBusMessage::createMethodCall(
-      QStringLiteral("SetLinkDNS"), argumentList);
+      DBUS_RESOLVE_SERVICE, DBUS_RESOLVE_PATH, DBUS_RESOLVE_MANAGER, "SetLinkDNS");
+  msg.setArguments(argumentList);
+  QDBusPendingReply<> reply = QDBusConnection::systemBus().asyncCall(msg, 5000);
 
   QDBusPendingCallWatcher* watcher = new QDBusPendingCallWatcher(reply, this);
   QObject::connect(watcher, SIGNAL(finished(QDBusPendingCallWatcher*)), this,
@@ -121,6 +221,7 @@ void DnsUtilsLinux::setLinkDNS(int ifindex,
 
 void DnsUtilsLinux::setLinkDomains(int ifindex,
                                    const QList<DnsLinkDomain>& domains) {
+  if (!m_resolver) return;
   char ifnamebuf[IF_NAMESIZE];
   const char* ifname = if_indextoname(ifindex, ifnamebuf);
   if (ifname) {
@@ -135,8 +236,10 @@ void DnsUtilsLinux::setLinkDomains(int ifindex,
   QList<QVariant> argumentList;
   argumentList << QVariant::fromValue(ifindex);
   argumentList << QVariant::fromValue(domains);
-  QDBusPendingReply<> reply = m_resolver->asyncCallWithArgumentList(
+  QDBusMessage msg = QDBusMessage::createMethodCall(
-      QStringLiteral("SetLinkDomains"), argumentList);
+      DBUS_RESOLVE_SERVICE, DBUS_RESOLVE_PATH, DBUS_RESOLVE_MANAGER, "SetLinkDomains");
+  msg.setArguments(argumentList);
+  QDBusPendingReply<> reply = QDBusConnection::systemBus().asyncCall(msg, 5000);
 
   QDBusPendingCallWatcher* watcher = new QDBusPendingCallWatcher(reply, this);
   QObject::connect(watcher, SIGNAL(finished(QDBusPendingCallWatcher*)), this,
@@ -144,11 +247,14 @@ void DnsUtilsLinux::setLinkDomains(int ifindex,
 }
 
 void DnsUtilsLinux::setLinkDefaultRoute(int ifindex, bool enable) {
+  if (!m_resolver) return;
   QList<QVariant> argumentList;
   argumentList << QVariant::fromValue(ifindex);
   argumentList << QVariant::fromValue(enable);
-  QDBusPendingReply<> reply = m_resolver->asyncCallWithArgumentList(
+  QDBusMessage msg = QDBusMessage::createMethodCall(
-      QStringLiteral("SetLinkDefaultRoute"), argumentList);
+      DBUS_RESOLVE_SERVICE, DBUS_RESOLVE_PATH, DBUS_RESOLVE_MANAGER, "SetLinkDefaultRoute");
+  msg.setArguments(argumentList);
+  QDBusPendingReply<> reply = QDBusConnection::systemBus().asyncCall(msg, 5000);
 
   QDBusPendingCallWatcher* watcher = new QDBusPendingCallWatcher(reply, this);
   QObject::connect(watcher, SIGNAL(finished(QDBusPendingCallWatcher*)), this,
@@ -156,6 +262,7 @@ void DnsUtilsLinux::setLinkDefaultRoute(int ifindex, bool enable) {
 }
 
 void DnsUtilsLinux::updateLinkDomains() {
+  if (!m_resolver) return;
   /* Get the list of search domains, and remove any others that might conspire
    * to satisfy DNS resolution. Unfortunately, this is a pain because Qt doesn't
    * seem to be able to demarshall complex property types.
@@ -165,7 +272,7 @@ void DnsUtilsLinux::updateLinkDomains() {
   message << QString(DBUS_RESOLVE_MANAGER);
   message << QString("Domains");
   QDBusPendingReply<QVariant> reply =
-      m_resolver->connection().asyncCall(message);
+      m_resolver->connection().asyncCall(message, 5000);
 
   QDBusPendingCallWatcher* watcher = new QDBusPendingCallWatcher(reply, this);
   QObject::connect(watcher, SIGNAL(finished(QDBusPendingCallWatcher*)), this,
@@ -174,11 +281,13 @@ void DnsUtilsLinux::updateLinkDomains() {
 
 void DnsUtilsLinux::dnsDomainsReceived(QDBusPendingCallWatcher* call) {
   QDBusPendingReply<QVariant> reply = *call;
+  call->deleteLater();
   if (reply.isError()) {
-    logger.error() << "Error retrieving the DNS  domains from the DBus service";
+    logger.debug() << "DBus Domains call failed (may be transient after systemd-resolved restart)";
-    delete call;
+    scheduleRetry();
     return;
   }
+  m_domainRetries = 0;
 
   /* Update the state of the DNS domains */
   m_linkDomains.clear();
@@ -204,9 +313,17 @@ void DnsUtilsLinux::dnsDomainsReceived(QDBusPendingCallWatcher* call) {
   }
 
   /* Add a root search domain for the new interface. */
-  QList<DnsLinkDomain> newlist = {root};
+  if (m_ifindex > 0) {
-  setLinkDomains(m_ifindex, newlist);
+    setLinkDomains(m_ifindex, {root});
-  delete call;
+
+    /* Disable DefaultRoute on the physical gateway so systemd-resolved
+     * routes all DNS through the VPN interface. */
+    const int gwIdx = NetworkUtilities::getGatewayAndIface().second.index();
+    if (gwIdx > 0 && gwIdx != m_ifindex && gwIdx != m_gatewayIfindex) {
+      m_gatewayIfindex = gwIdx;
+      setLinkDefaultRoute(gwIdx, false);
+    }
+  }
 }
 
 static DnsMetatypeRegistrationProxy s_dnsMetatypeProxy;

client/platforms/linux/daemon/dnsutilslinux.h

@@ -6,7 +6,12 @@
 #define DNSUTILSLINUX_H
 
 #include <QDBusInterface>
+#include <QScopedPointer>
 #include <QDBusPendingCallWatcher>
+#include <QDBusServiceWatcher>
+#include <QHostAddress>
+#include <QList>
+#include <QString>
 
 #include "daemon/dnsutils.h"
 #include "dbustypeslinux.h"
@@ -29,13 +34,25 @@ class DnsUtilsLinux final : public DnsUtils {
   void updateLinkDomains();
 
  private slots:
+  void onResolverRegistered();
+  void onResolverUnregistered();
   void dnsCallCompleted(QDBusPendingCallWatcher*);
   void dnsDomainsReceived(QDBusPendingCallWatcher*);
 
+ private:
+  void scheduleRetry();
+
  private:
   int m_ifindex = 0;
+  int m_gatewayIfindex = 0;
+  int m_domainRetries = 0;
+  bool m_revertOnDestroy = false;
+  bool m_retryPending = false;
+  int m_revertAfterRegister = 0;
   QMap<int, DnsLinkDomainList> m_linkDomains;
-  QDBusInterface* m_resolver = nullptr;
+  QScopedPointer<QDBusInterface> m_resolver;
+  QString m_pendingIfname;
+  QList<QHostAddress> m_pendingResolvers;
 };
 
 #endif  // DNSUTILSLINUX_H

client/platforms/linux/daemon/linuxfirewall.cpp

@@ -33,6 +33,7 @@
 #include "linuxfirewall.h"
 #include "logger.h"
 #include "xray_defs.h"
+#include <QFileInfo>
 #include <QProcess>
 
 #define BRAND_CODE "amn"
@@ -102,14 +103,7 @@ int LinuxFirewall::linkChain(LinuxFirewall::IPVersion ip, const QString& chain,
     const QString cmd = getCommand(ip);
     if (mustBeFirst)
     {
-        // This monster shell script does the following:
+        return execute(QStringLiteral("if ! %1 -L %2 -n --line-numbers -t %4 2> /dev/null | awk 'int($1) == 1 && $2 == \"%3\" { found=1 } END { if(found==1) { exit 0 } else { exit 1 } }' ; then %1 -I %2 -j %3 -t %4 && %1 -L %2 -n --line-numbers -t %4 2> /dev/null | awk 'int($1) > 1 && $2 == \"%3\" { print $1; exit }' | xargs -r %1 -t %4 -D %2 ; fi").arg(cmd, parent, chain, tableName));
-        // 1. Check if a rule with the appropriate target exists at the top of the parent chain
-        // 2. If not, insert a jump rule at the top of the parent chain
-        // 3. Look for and delete a single rule with the designated target at an index > 1
-        //    (we can't safely delete all rules at once since rule numbers change)
-        // TODO: occasionally this script results in warnings in logs "Bad rule (does a matching rule exist in the chain?)" - this happens when
-        // the e.g OUTPUT chain is empty but this script attempts to delete things from it anyway. It doesn't cause any problems, but we should still fix at some point..
-        return execute(QStringLiteral("if ! %1 -L %2 -n --line-numbers -t %4 2> /dev/null | awk 'int($1) == 1 && $2 == \"%3\" { found=1 } END { if(found==1) { exit 0 } else { exit 1 } }' ; then %1 -I %2 -j %3 -t %4 && %1 -L %2 -n --line-numbers -t %4 2> /dev/null | awk 'int($1) > 1 && $2 == \"%3\" { print $1; exit }' | xargs %1 -t %4 -D %2 ; fi").arg(cmd, parent, chain, tableName));
     }
     else
         return execute(QStringLiteral("if ! %1 -C %2 -j %3 -t %4 2> /dev/null ; then %1 -A %2 -j %3 -t %4; fi").arg(cmd, parent, chain, tableName));
@@ -291,6 +285,8 @@ void LinuxFirewall::install()
 
     installAnchor(IPv4, QStringLiteral("110.allowNets"), {});
 
+    installAnchor(Both, QStringLiteral("400.allowPIA"), {});
+
     installAnchor(Both, QStringLiteral("100.blockAll"), {
                                                             QStringLiteral("-j REJECT"),
                                                         });
@@ -454,16 +450,33 @@ void LinuxFirewall::updateDNSServers(const QStringList& servers)
     static QStringList existingServers {};
 
     existingServers = servers;
-    execute(QStringLiteral("iptables -F %1.320.allowDNS").arg(kAnchorName));
+    const QString chain = QStringLiteral("%1.320.allowDNS").arg(kAnchorName);
-    for (const QString& rule : getDNSRules(servers))
+    executeIptables(QStringLiteral("iptables"), {QStringLiteral("-F"), chain});
-        execute(QStringLiteral("iptables -A %1.320.allowDNS %2").arg(kAnchorName, rule));
+    const QStringList ifaces = {
+        QStringLiteral("amn0+"), QStringLiteral("tun0+"), QStringLiteral("tun2+")
+    };
+    for (const QString& server : servers) {
+        for (const QString& iface : ifaces) {
+            executeIptables(QStringLiteral("iptables"),
+                {QStringLiteral("-A"), chain, QStringLiteral("-o"), iface,
+                 QStringLiteral("-d"), server, QStringLiteral("-p"), QStringLiteral("udp"),
+                 QStringLiteral("--dport"), QStringLiteral("53"), QStringLiteral("-j"), QStringLiteral("ACCEPT")});
+            executeIptables(QStringLiteral("iptables"),
+                {QStringLiteral("-A"), chain, QStringLiteral("-o"), iface,
+                 QStringLiteral("-d"), server, QStringLiteral("-p"), QStringLiteral("tcp"),
+                 QStringLiteral("--dport"), QStringLiteral("53"), QStringLiteral("-j"), QStringLiteral("ACCEPT")});
+        }
+    }
 }
 
 void LinuxFirewall::updateAllowNets(const QStringList& servers)
 {
-    execute(QStringLiteral("iptables -F %1.110.allowNets").arg(kAnchorName));
+    const QString chain = QStringLiteral("%1.110.allowNets").arg(kAnchorName);
-    for (const QString& rule : getAllowRule(servers))
+    executeIptables(QStringLiteral("iptables"), {QStringLiteral("-F"), chain});
-        execute(QStringLiteral("iptables -A %1.110.allowNets %2").arg(kAnchorName, rule));
+    for (const QString& server : servers)
+        executeIptables(QStringLiteral("iptables"),
+            {QStringLiteral("-A"), chain, QStringLiteral("-d"), server,
+             QStringLiteral("-j"), QStringLiteral("ACCEPT")});
 }
 
 void LinuxFirewall::updateBlockNets(const QStringList& servers)
@@ -471,9 +484,12 @@ void LinuxFirewall::updateBlockNets(const QStringList& servers)
     static QStringList existingServers {};
 
     existingServers = servers;
-    execute(QStringLiteral("iptables -F %1.120.blockNets").arg(kAnchorName));
+    const QString chain = QStringLiteral("%1.120.blockNets").arg(kAnchorName);
-    for (const QString& rule : getBlockRule(servers))
+    executeIptables(QStringLiteral("iptables"), {QStringLiteral("-F"), chain});
-        execute(QStringLiteral("iptables -A %1.120.blockNets %2").arg(kAnchorName, rule));
+    for (const QString& server : servers)
+        executeIptables(QStringLiteral("iptables"),
+            {QStringLiteral("-A"), chain, QStringLiteral("-d"), server,
+             QStringLiteral("-j"), QStringLiteral("REJECT")});
 }
 
 int waitForExitCode(QProcess& process)
@@ -506,10 +522,39 @@ int LinuxFirewall::execute(const QString &command, bool ignoreErrors)
     return exitCode;
 }
 
+int LinuxFirewall::executeIptables(const QString &program, const QStringList &args, bool ignoreErrors)
+{
+    QProcess p;
+    p.start(program, args, QProcess::ReadOnly);
+    p.closeWriteChannel();
+
+    int exitCode = waitForExitCode(p);
+    auto out = p.readAllStandardOutput().trimmed();
+    auto err = p.readAllStandardError().trimmed();
+    if ((exitCode != 0 || !err.isEmpty()) && !ignoreErrors)
+        logger.warning() << "(" << exitCode << ") $ " << program << args.join(QLatin1Char(' '));
+    if (!out.isEmpty())
+        logger.info() << out;
+    if (!err.isEmpty())
+        logger.warning() << err;
+    return exitCode;
+}
+
 void LinuxFirewall::setupTrafficSplitting()
 {
+    const QString cgroupBase = QStringLiteral("/sys/fs/cgroup/net_cls");
+    if (!QFileInfo::exists(cgroupBase)) {
+        logger.warning() << "net_cls cgroup v1 not available, traffic splitting disabled";
+        return;
+    }
+
+    execute(QStringLiteral(
+        "if ! grep -qE '^[0-9]+[[:space:]]+%1$' /etc/iproute2/rt_tables 2>/dev/null ; then "
+        "echo '200 %1' >> /etc/iproute2/rt_tables ; fi"
+    ).arg(kRtableName));
+
     auto cGroupDir = "/sys/fs/cgroup/net_cls/" BRAND_CODE "vpnexclusions/";
-    logger.info() << "Should be setting up cgroup in" << cGroupDir << "for traffic splitting";
+    logger.info() << "Setting up cgroup in" << cGroupDir << "for traffic splitting";
     execute(QStringLiteral("if [ ! -d %1 ] ; then mkdir %1 ; sleep 0.1 ; echo %2 > %1/net_cls.classid ; fi").arg(cGroupDir).arg(kCGroupId));
     // Set a rule with priority 100 (lower priority than local but higher than main/default, 0 is highest priority)
     execute(QStringLiteral("if ! ip rule list | grep -q %1 ; then ip rule add from all fwmark %1 lookup %2 pri 100 ; fi").arg(kPacketTag, kRtableName));
@@ -518,7 +563,7 @@ void LinuxFirewall::setupTrafficSplitting()
 void LinuxFirewall::teardownTrafficSplitting()
 {
     logger.info() << "Tearing down cgroup and routing rules";
-    execute(QStringLiteral("if ip rule list | grep -q %1; then ip rule del from all fwmark %1 lookup %2 2> /dev/null ; fi").arg(kPacketTag, kRtableName));
+    execute(QStringLiteral("if ip rule list | grep -q %1; then ip rule del from all fwmark %1 lookup %2 2>/dev/null ; fi").arg(kPacketTag, kRtableName));
-    execute(QStringLiteral("ip route flush table %1").arg(kRtableName));
+    execute(QStringLiteral("ip route flush table %1 2>/dev/null || true").arg(kRtableName));
     execute(QStringLiteral("ip route flush cache"));
 }

client/platforms/linux/daemon/linuxfirewall.h

@@ -85,6 +85,7 @@ private:
     static void setupTrafficSplitting();
     static void teardownTrafficSplitting();
     static int execute(const QString& command, bool ignoreErrors = false);
+    static int executeIptables(const QString& program, const QStringList& args, bool ignoreErrors = false);
 private:
     // Chain names
     static QString kOutputChain, kRootChain, kPostRoutingChain, kPreRoutingChain;

client/platforms/linux/daemon/wireguardutilslinux.cpp

@@ -237,7 +237,11 @@ bool WireguardUtilsLinux::updatePeer(const InterfaceConfig& config) {
     // Exclude the server address, except for multihop exit servers.
     if ((config.m_hopType != InterfaceConfig::MultiHopExit) &&
         (m_rtmonitor != nullptr)) {
-        m_rtmonitor->addExclusionRoute(IPAddress(config.m_serverIpv4AddrIn));
+        if (!config.m_serverIpv4AddrIn.isEmpty() &&
+            !m_rtmonitor->addExclusionRoute(IPAddress(config.m_serverIpv4AddrIn))) {
+            logger.error() << "No gateway — cannot add server exclusion route";
+            return false;
+        }
         m_rtmonitor->addExclusionRoute(IPAddress(config.m_serverIpv6AddrIn));
     }
 

client/vpnConnection.cpp

@@ -17,6 +17,7 @@
 #ifdef AMNEZIA_DESKTOP
     #include "core/utils/ipcClient.h"
     #include <core/protocols/wireGuardProtocol.h>
+    #include "daemon/wireguardutils.h"
 #endif
 
 #ifdef Q_OS_ANDROID
@@ -127,6 +128,23 @@ void VpnConnection::onConnectionStateChanged(Vpn::ConnectionState state)
                 else
                     qWarning() << "VpnConnection::onConnectionStateChanged: Failed to flush DNS";
 
+#ifdef Q_OS_LINUX
+                if (ContainerUtils::isAwgContainer(container) || container == DockerContainer::WireGuard) {
+                    QString dns1 = m_vpnConfiguration.value(configKey::dns1).toString();
+                    QString dns2 = m_vpnConfiguration.value(configKey::dns2).toString();
+                    QList<QHostAddress> resolvers;
+                    if (!dns1.isEmpty()) resolvers << QHostAddress(dns1);
+                    if (!dns2.isEmpty()) resolvers << QHostAddress(dns2);
+                    if (!resolvers.isEmpty()) {
+                        auto r = iface->updateResolvers(WG_INTERFACE, resolvers);
+                        if (r.waitForFinished() && r.returnValue())
+                            qDebug() << "VpnConnection: DNS resolvers set via systemd-resolved";
+                        else
+                            qWarning() << "VpnConnection: Failed to set DNS resolvers";
+                    }
+                }
+#endif
+
                 if (!ContainerUtils::isAwgContainer(container) && container != DockerContainer::WireGuard) {
                     QString dns1 = m_vpnConfiguration.value(configKey::dns1).toString();
                     QString dns2 = m_vpnConfiguration.value(configKey::dns2).toString();
@@ -160,6 +178,11 @@ void VpnConnection::onConnectionStateChanged(Vpn::ConnectionState state)
             } break;
             case Vpn::ConnectionState::Disconnected:
             case Vpn::ConnectionState::Error: {
+#ifdef Q_OS_LINUX
+                if (ContainerUtils::isAwgContainer(container) || container == DockerContainer::WireGuard) {
+                    iface->restoreResolvers();
+                }
+#endif
                 auto flushDns = iface->flushDns();
                 if (flushDns.waitForFinished() && flushDns.returnValue())
                     qDebug() << "VpnConnection::onConnectionStateChanged: Successfully flushed DNS";

ipc/ipc.h

@@ -3,6 +3,8 @@
 
 #include <QObject>
 #include <QString>
+#include <QRegularExpression>
+#include <QSet>
 
 #include "../client/core/utils/utilities.h"
 
@@ -15,7 +17,8 @@ enum PermittedProcess {
     OpenVPN,
     Wireguard,
     Tun2Socks,
-    CertUtil
+    CertUtil,
+    _Count
 };
 
 inline QString permittedProcessPath(PermittedProcess pid)
@@ -57,16 +60,56 @@ inline QStringList sanitizeArguments(PermittedProcess proc, const QStringList &a
     QList<Validator> positionalArgs;
 
     switch (proc) {
+    case OpenVPN: {
+        static const QSet<QString> blocked = {
+            QStringLiteral("--script-security"),
+            QStringLiteral("--up"),
+            QStringLiteral("--down"),
+            QStringLiteral("--route-up"),
+            QStringLiteral("--ipchange"),
+            QStringLiteral("--tls-verify"),
+            QStringLiteral("--plugin"),
+            QStringLiteral("--auth-user-pass-verify"),
+            QStringLiteral("--learn-address"),
+            QStringLiteral("--client-connect"),
+            QStringLiteral("--client-disconnect"),
+            QStringLiteral("--management"),
+            QStringLiteral("--management-external-key")
+        };
+        QStringList out;
+        for (int i = 0; i < args.size(); ++i) {
+            if (blocked.contains(args[i])) {
+                qWarning() << "IPC: blocked OpenVPN argument:" << args[i];
+                ++i; // skip following value
+                continue;
+            }
+            out << args[i];
+        }
+        return out;
+    }
+    case Wireguard: {
+        static const QRegularExpression hookRe(
+            QStringLiteral(R"((?i)(PostUp|PreUp|PostDown|PreDown)\s*=)"));
+        QStringList out;
+        for (const QString& a : args) {
+            if (hookRe.match(a).hasMatch()) {
+                qWarning() << "IPC: blocked WireGuard hook argument:" << a;
+                continue;
+            }
+            out << a;
+        }
+        return out;
+    }
     case Tun2Socks:
         namedArgs["-device"] = [](const QString& v) { return v.startsWith("tun://"); };
         namedArgs["-proxy"] = [](const QString& v) { return v.startsWith("socks5://"); };
         break;
-    default:
+    case CertUtil:
-        //FIXME
         return args;
+    default:
+        return {};
     }
 
-
     QStringList sanitized;
 
     for (int i = 0, pos = 0; i < args.size(); i++) {

ipc/ipcserver.cpp

@@ -22,6 +22,27 @@
     #include "tapcontroller_win.h"
 #endif
 
+#ifdef Q_OS_LINUX
+#include <sys/socket.h>
+#include <sys/types.h>
+
+extern uid_t g_allowedUid;
+extern bool g_allowedUidSet;
+
+static bool checkPrivPeerCredentials(QLocalSocket *socket) {
+    struct ucred cred{};
+    socklen_t len = sizeof(cred);
+    if (getsockopt(socket->socketDescriptor(), SOL_SOCKET, SO_PEERCRED, &cred, &len) != 0) {
+        qWarning() << "IpcServer: SO_PEERCRED failed, rejecting privileged process connection";
+        return false;
+    }
+    if (cred.uid == 0) return true;
+    if (g_allowedUidSet && cred.uid == g_allowedUid) return true;
+    qWarning() << "IpcServer: rejected privileged process connection from unauthorized UID" << cred.uid;
+    return false;
+}
+#endif
+
 
 IpcServer::IpcServer(QObject *parent) : IpcInterfaceSource(parent)
 {
@@ -48,8 +69,16 @@ int IpcServer::createPrivilegedProcess()
     // Make sure any connections are handed to QtRO
     QObject::connect(pd.localServer.data(), &QLocalServer::newConnection, this, [pd]() {
         qDebug() << "IpcServer new connection";
+        QLocalSocket *conn = pd.localServer->nextPendingConnection();
+#ifdef Q_OS_LINUX
+        if (!checkPrivPeerCredentials(conn)) {
+            conn->close();
+            conn->deleteLater();
+            return;
+        }
+#endif
         if (pd.serverNode) {
-            pd.serverNode->addHostSideConnection(pd.localServer->nextPendingConnection());
+            pd.serverNode->addHostSideConnection(conn);
             pd.serverNode->enableRemoting(pd.ipcProcess.data());
         }
     });

ipc/ipcserverprocess.cpp

@@ -77,6 +77,11 @@ void IpcServerProcess::setProcessChannelMode(QProcess::ProcessChannelMode mode)
 
 void IpcServerProcess::setProgram(int programId)
 {
+    if (programId <= static_cast<int>(amnezia::PermittedProcess::Invalid) ||
+        programId >= static_cast<int>(amnezia::PermittedProcess::_Count)) {
+        qWarning() << "IPC: invalid programId" << programId << ", ignoring";
+        return;
+    }
     m_program = static_cast<amnezia::PermittedProcess>(programId);
     m_process->setProgram(amnezia::permittedProcessPath(m_program));
     m_process->setArguments({});

service/server/killswitch.cpp

@@ -3,6 +3,7 @@
 
 #include <QApplication>
 #include <QHostAddress>
+#include <QRegularExpression>
 
 #include "../client/core/utils/protocolEnum.h"
 #include "../client/core/protocols/protocolUtils.h"
@@ -11,6 +12,37 @@
 #include "qjsonarray.h"
 #include "version.h"
 
+#if defined(Q_OS_LINUX) || defined(Q_OS_MACOS)
+static bool isValidIpOrCidr(const QString &value) {
+    static const QRegularExpression re(
+        QStringLiteral(R"(^(\d{1,3}\.){3}\d{1,3}(/\d{1,2})?$)"));
+    if (!re.match(value).hasMatch()) return false;
+    const QStringList ipParts = value.split(QLatin1Char('/'))[0].split(QLatin1Char('.'));
+    for (const QString &part : ipParts) {
+        bool ok;
+        int octet = part.toInt(&ok);
+        if (!ok || octet < 0 || octet > 255) return false;
+    }
+    if (value.contains(QLatin1Char('/'))) {
+        bool ok;
+        int prefix = value.split(QLatin1Char('/'))[1].toInt(&ok);
+        if (!ok || prefix < 0 || prefix > 32) return false;
+    }
+    return true;
+}
+
+static QStringList filterIpList(const QStringList &values) {
+    QStringList safe;
+    for (const QString &v : values) {
+        if (isValidIpOrCidr(v))
+            safe << v;
+        else
+            qWarning() << "IPC: rejected invalid IP/CIDR value:" << v;
+    }
+    return safe;
+}
+#endif
+
 #ifdef Q_OS_WIN
     #include "../client/platforms/windows/daemon/windowsfirewall.h"
     #include "../client/platforms/windows/daemon/windowsdaemon.h"
@@ -166,7 +198,11 @@ bool KillSwitch::disableAllTraffic() {
 
 bool KillSwitch::resetAllowedRange(const QStringList &ranges) {
 
+#ifdef Q_OS_LINUX
+    m_allowedRanges = filterIpList(ranges);
+#else
     m_allowedRanges = ranges;
+#endif
 
 #ifdef Q_OS_LINUX
     LinuxFirewall::setAnchorEnabled(LinuxFirewall::IPv4, QStringLiteral("110.allowNets"), true);
@@ -189,7 +225,12 @@ bool KillSwitch::resetAllowedRange(const QStringList &ranges) {
 }
 
 bool KillSwitch::addAllowedRange(const QStringList &ranges) {
-    for (const QString &range : ranges) {
+#ifdef Q_OS_LINUX
+    const QStringList safeRanges = filterIpList(ranges);
+#else
+    const QStringList &safeRanges = ranges;
+#endif
+    for (const QString &range : safeRanges) {
         if (!range.isEmpty() && !m_allowedRanges.contains(range)) {
             m_allowedRanges.append(range);
         }
@@ -317,9 +358,9 @@ bool KillSwitch::enableKillSwitch(const QJsonObject &configStr, int vpnAdapterIn
     LinuxFirewall::setAnchorEnabled(LinuxFirewall::Both, QStringLiteral("000.allowLoopback"), true);
     LinuxFirewall::setAnchorEnabled(LinuxFirewall::Both, QStringLiteral("100.blockAll"), blockAll);
     LinuxFirewall::setAnchorEnabled(LinuxFirewall::IPv4, QStringLiteral("110.allowNets"), allowNets);
-    LinuxFirewall::updateAllowNets(allownets);
+    LinuxFirewall::updateAllowNets(filterIpList(allownets));
     LinuxFirewall::setAnchorEnabled(LinuxFirewall::IPv4, QStringLiteral("120.blockNets"), blockAll);
-    LinuxFirewall::updateBlockNets(blocknets);
+    LinuxFirewall::updateBlockNets(filterIpList(blocknets));
     LinuxFirewall::setAnchorEnabled(LinuxFirewall::Both, QStringLiteral("130.allowMarkedXray"), true);
     LinuxFirewall::setAnchorEnabled(LinuxFirewall::IPv4, QStringLiteral("200.allowVPN"), true);
     LinuxFirewall::setAnchorEnabled(LinuxFirewall::IPv6, QStringLiteral("250.blockIPv6"), true);
@@ -328,21 +369,34 @@ bool KillSwitch::enableKillSwitch(const QJsonObject &configStr, int vpnAdapterIn
     LinuxFirewall::setAnchorEnabled(LinuxFirewall::IPv4, QStringLiteral("310.blockDNS"), true);
     QStringList dnsServers;
 
-    dnsServers.append(configStr.value(amnezia::configKey::dns1).toString());
+    const QString dns1 = configStr.value(amnezia::configKey::dns1).toString();
+    if (isValidIpOrCidr(dns1))
+        dnsServers.append(dns1);
+    else if (!dns1.isEmpty())
+        qWarning() << "IPC: rejected invalid dns1:" << dns1;
 
     // We don't use secondary DNS if primary DNS is AmneziaDNS
-    if (!configStr.value(amnezia::configKey::dns1).toString().contains(amnezia::protocols::dns::amneziaDnsIp)) {
+    if (!dns1.contains(amnezia::protocols::dns::amneziaDnsIp)) {
-        dnsServers.append(configStr.value(amnezia::configKey::dns2).toString());
+        const QString dns2 = configStr.value(amnezia::configKey::dns2).toString();
+        if (isValidIpOrCidr(dns2))
+            dnsServers.append(dns2);
+        else if (!dns2.isEmpty())
+            qWarning() << "IPC: rejected invalid dns2:" << dns2;
     }
 
     dnsServers.append("127.0.0.1");
     dnsServers.append("127.0.0.53");
 
+
     for (auto dns : configStr.value(amnezia::configKey::allowedDnsServers).toArray()) {
         if (!dns.isString()) {
             break;
         }
-        dnsServers.append(dns.toString());
+        const QString dnsStr = dns.toString();
+        if (isValidIpOrCidr(dnsStr))
+            dnsServers.append(dnsStr);
+        else if (!dnsStr.isEmpty())
+            qWarning() << "IPC: rejected invalid allowedDnsServer:" << dnsStr;
     }
 
     LinuxFirewall::updateDNSServers(dnsServers);
@@ -360,28 +414,40 @@ bool KillSwitch::enableKillSwitch(const QJsonObject &configStr, int vpnAdapterIn
     MacOSFirewall::setAnchorEnabled(QStringLiteral("000.allowLoopback"), true);
     MacOSFirewall::setAnchorEnabled(QStringLiteral("100.blockAll"), blockAll);
     MacOSFirewall::setAnchorEnabled(QStringLiteral("110.allowNets"), allowNets);
-    MacOSFirewall::setAnchorTable(QStringLiteral("110.allowNets"), allowNets, QStringLiteral("allownets"), allownets);
+    MacOSFirewall::setAnchorTable(QStringLiteral("110.allowNets"), allowNets, QStringLiteral("allownets"), filterIpList(allownets));
 
     MacOSFirewall::setAnchorEnabled(QStringLiteral("120.blockNets"), blockNets);
-    MacOSFirewall::setAnchorTable(QStringLiteral("120.blockNets"), blockNets, QStringLiteral("blocknets"), blocknets);
+    MacOSFirewall::setAnchorTable(QStringLiteral("120.blockNets"), blockNets, QStringLiteral("blocknets"), filterIpList(blocknets));
     MacOSFirewall::setAnchorEnabled(QStringLiteral("200.allowVPN"), true);
     MacOSFirewall::setAnchorEnabled(QStringLiteral("250.blockIPv6"), true);
     MacOSFirewall::setAnchorEnabled(QStringLiteral("290.allowDHCP"), true);
     MacOSFirewall::setAnchorEnabled(QStringLiteral("300.allowLAN"), true);
 
     QStringList dnsServers;
-    dnsServers.append(configStr.value(amnezia::configKey::dns1).toString());
+    const QString dns1 = configStr.value(amnezia::configKey::dns1).toString();
+    if (isValidIpOrCidr(dns1))
+        dnsServers.append(dns1);
+    else if (!dns1.isEmpty())
+        qWarning() << "IPC: rejected invalid dns1:" << dns1;
 
     // We don't use secondary DNS if primary DNS is AmneziaDNS
-    if (!configStr.value(amnezia::configKey::dns1).toString().contains(amnezia::protocols::dns::amneziaDnsIp)) {
+    if (!dns1.contains(amnezia::protocols::dns::amneziaDnsIp)) {
-        dnsServers.append(configStr.value(amnezia::configKey::dns2).toString());
+        const QString dns2 = configStr.value(amnezia::configKey::dns2).toString();
+        if (isValidIpOrCidr(dns2))
+            dnsServers.append(dns2);
+        else if (!dns2.isEmpty())
+            qWarning() << "IPC: rejected invalid dns2:" << dns2;
     }
 
     for (auto dns : configStr.value(amnezia::configKey::allowedDnsServers).toArray()) {
         if (!dns.isString()) {
             break;
         }
-        dnsServers.append(dns.toString());
+        const QString dnsStr = dns.toString();
+        if (isValidIpOrCidr(dnsStr))
+            dnsServers.append(dnsStr);
+        else if (!dnsStr.isEmpty())
+            qWarning() << "IPC: rejected invalid allowedDnsServer:" << dnsStr;
     }
     
     MacOSFirewall::setAnchorEnabled(QStringLiteral("310.blockDNS"), true);

service/server/localserver.cpp

@@ -17,6 +17,35 @@
     #include "tapcontroller_win.h"
 #endif
 
+#ifdef Q_OS_LINUX
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+uid_t g_allowedUid = static_cast<uid_t>(-1);
+bool g_allowedUidSet = false;
+
+static bool checkPeerCredentials(QLocalSocket *socket) {
+    struct ucred cred{};
+    socklen_t len = sizeof(cred);
+    if (getsockopt(socket->socketDescriptor(), SOL_SOCKET, SO_PEERCRED, &cred, &len) != 0) {
+        qWarning() << "LocalServer: SO_PEERCRED failed, rejecting connection";
+        return false;
+    }
+    if (cred.uid == 0) return true;
+    if (!g_allowedUidSet) {
+        g_allowedUid = cred.uid;
+        g_allowedUidSet = true;
+        qDebug() << "LocalServer: registered session UID" << g_allowedUid;
+    }
+    if (cred.uid != g_allowedUid) {
+        qWarning() << "LocalServer: rejected connection from unauthorized UID" << cred.uid;
+        return false;
+    }
+    return true;
+}
+#endif
+
 namespace {
 Logger logger("WgDaemonServer");
 }
@@ -35,7 +64,15 @@ LocalServer::LocalServer(QObject *parent) : QObject(parent),
 
     QObject::connect(m_server.data(), &QLocalServer::newConnection, this, [this]() {
         qDebug() << "LocalServer new connection";
-        m_serverNode.addHostSideConnection(m_server->nextPendingConnection());
+        QLocalSocket *conn = m_server->nextPendingConnection();
+#ifdef Q_OS_LINUX
+        if (!checkPeerCredentials(conn)) {
+            conn->close();
+            conn->deleteLater();
+            return;
+        }
+#endif
+        m_serverNode.addHostSideConnection(conn);
 
         if (!m_isRemotingEnabled) {
             m_isRemotingEnabled = true;

service/server/router_linux.cpp

@@ -182,7 +182,7 @@ bool RouterLinux::flushDns()
     if (output.isEmpty())
         qDebug().noquote() << "Flush dns completed";
     else
-        qDebug().noquote() << "OUTPUT systemctl restart nscd/systemd-resolved: " + output;
+        qDebug().noquote() << "OUTPUT systemctl restart: " + output;
 
     return true;
 }