*** empty log message ***
[l2tpns.git] / l2tpns.c
index 5bac272..193e333 100644 (file)
--- a/l2tpns.c
+++ b/l2tpns.c
@@ -4,7 +4,7 @@
 // Copyright (c) 2002 FireBrick (Andrews & Arnold Ltd / Watchfront Ltd) - GPL licenced
 // vim: sw=8 ts=8
 
-char const *cvs_id_l2tpns = "$Id: l2tpns.c,v 1.118 2005-08-10 08:36:48 bodea Exp $";
+char const *cvs_id_l2tpns = "$Id: l2tpns.c,v 1.134 2005-09-16 05:30:30 bodea Exp $";
 
 #include <arpa/inet.h>
 #include <assert.h>
@@ -75,6 +75,10 @@ static int syslog_log = 0;   // are we logging to syslog
 static FILE *log_stream = 0;   // file handle for direct logging (i.e. direct into file, not via syslog).
 uint32_t last_id = 0;          // Unique ID for radius accounting
 
+// calculated from config->l2tp_mtu
+uint16_t MRU = 0;              // PPP MRU
+uint16_t MSS = 0;              // TCP MSS
+
 struct cli_session_actions *cli_session_actions = NULL;        // Pending session changes requested by CLI
 struct cli_tunnel_actions *cli_tunnel_actions = NULL;  // Pending tunnel changes required by CLI
 
@@ -104,7 +108,8 @@ config_descriptt config_values[] = {
        CONFIG("log_file", log_filename, STRING),
        CONFIG("pid_file", pid_file, STRING),
        CONFIG("random_device", random_device, STRING),
-       CONFIG("l2tp_secret", l2tpsecret, STRING),
+       CONFIG("l2tp_secret", l2tp_secret, STRING),
+       CONFIG("l2tp_mtu", l2tp_mtu, INT),
        CONFIG("ppp_restart_time", ppp_restart_time, INT),
        CONFIG("ppp_max_configure", ppp_max_configure, INT),
        CONFIG("ppp_max_failure", ppp_max_failure, INT),
@@ -135,6 +140,7 @@ config_descriptt config_values[] = {
        CONFIG("packet_limit", max_packets, INT),
        CONFIG("cluster_address", cluster_address, IPv4),
        CONFIG("cluster_interface", cluster_interface, STRING),
+       CONFIG("cluster_mcast_ttl", cluster_mcast_ttl, INT),
        CONFIG("cluster_hb_interval", cluster_hb_interval, INT),
        CONFIG("cluster_hb_timeout", cluster_hb_timeout, INT),
        CONFIG("cluster_master_min_adv", cluster_master_min_adv, INT),
@@ -977,6 +983,50 @@ int tun_write(uint8_t * data, int size)
        return write(tunfd, data, size);
 }
 
+// adjust tcp mss to avoid fragmentation (called only for tcp packets with syn set)
+void adjust_tcp_mss(sessionidt s, tunnelidt t, uint8_t *buf, int len, uint8_t *tcp)
+{
+       int d = (tcp[12] >> 4) * 4;
+       uint8_t *mss = 0;
+       uint8_t *data;
+
+       if ((tcp[13] & 0x3f) & ~(TCP_FLAG_SYN|TCP_FLAG_ACK)) // only want SYN and SYN,ACK
+               return;
+
+       if (tcp + d > buf + len) // short?
+               return;
+
+       data = tcp + d;
+       tcp += 20;
+
+       while (tcp < data)
+       {
+               if (*tcp == 2 && tcp[1] == 4) // mss option (2), length 4
+               {
+                       mss = tcp + 2;
+                       if (mss + 2 > data) return; // short?
+                       break;
+               }
+
+               if (*tcp == 0) return; // end of options
+               if (*tcp == 1 || !tcp[1]) // no op (one byte), or no length (prevent loop)
+                       tcp++;
+               else
+                       tcp += tcp[1]; // skip over option
+       }
+
+       if (!mss) return; // not found
+       if (ntohs(*(uint16_t *) mss) <= MSS) return; // mss OK
+
+       LOG(5, s, t, "TCP: %s:%u -> %s:%u SYN%s, adjusted mss from %u to %u\n",
+               fmtaddr(*(in_addr_t *)(buf + 12), 0), ntohs(*(uint16_t *)tcp),
+               fmtaddr(*(in_addr_t *)(buf + 16), 1), ntohs(*(uint16_t *)(tcp + 2)),
+               (tcp[13] & TCP_FLAG_ACK) ? ",ACK" : "",
+               ntohs(*(uint16_t *) mss), MSS);
+
+       // FIXME
+}
+
 // process outgoing (to tunnel) IP
 //
 static void processipout(uint8_t *buf, int len)
@@ -1084,6 +1134,14 @@ static void processipout(uint8_t *buf, int len)
        if (session[s].filter_out && !ip_filter(buf, len, session[s].filter_out - 1))
                return;
 
+       // adjust MSS on SYN and SYN,ACK packets with options
+       if ((ntohs(*(uint16_t *) (buf + 6)) & 0x1fff) == 0 && buf[9] == IPPROTO_TCP) // first tcp fragment
+       {
+               int ihl = (buf[0] & 0xf) * 4; // length of IP header
+               if (len >= ihl + 20 && (buf[ihl + 13] & TCP_FLAG_SYN) && ((buf[ihl + 12] >> 4) > 5))
+                       adjust_tcp_mss(s, t, buf, len, buf + ihl);
+       }
+
        if (sp->tbf_out)
        {
                // Are we throttling this session?
@@ -1104,7 +1162,7 @@ static void processipout(uint8_t *buf, int len)
 
        // Add on L2TP header
        {
-               uint8_t *p = makeppp(b, sizeof(b), buf, len, t, s, PPPIP);
+               uint8_t *p = makeppp(b, sizeof(b), buf, len, s, t, PPPIP);
                if (!p) return;
                tunnelsend(b, len + (p-b), t); // send it...
        }
@@ -1215,7 +1273,7 @@ static void processipv6out(uint8_t * buf, int len)
 
        // Add on L2TP header
        {
-               uint8_t *p = makeppp(b, sizeof(b), buf, len, t, s, PPPIPV6);
+               uint8_t *p = makeppp(b, sizeof(b), buf, len, s, t, PPPIPV6);
                if (!p) return;
                tunnelsend(b, len + (p-b), t); // send it...
        }
@@ -1267,7 +1325,7 @@ static void send_ipout(sessionidt s, uint8_t *buf, int len)
 
        // Add on L2TP header
        {
-               uint8_t *p = makeppp(b, sizeof(b),  buf, len, t, s, PPPIP);
+               uint8_t *p = makeppp(b, sizeof(b), buf, len, s, t, PPPIP);
                if (!p) return;
                tunnelsend(b, len + (p-b), t); // send it...
        }
@@ -1366,7 +1424,7 @@ static void controlnull(tunnelidt t)
 }
 
 // add a control message to a tunnel, and send if within window
-static void controladd(controlt * c, tunnelidt t, sessionidt far)
+static void controladd(controlt *c, sessionidt far, tunnelidt t)
 {
        *(uint16_t *) (c->buf + 2) = htons(c->length); // length
        *(uint16_t *) (c->buf + 4) = htons(tunnel[t].far); // tunnel
@@ -1558,7 +1616,7 @@ void sessionshutdown(sessionidt s, char *reason, int result, int error)
                        control16(c, 1, result, 1);
 
                control16(c, 14, s, 1);   // assigned session (our end)
-               controladd(c, session[s].tunnel, session[s].far); // send the message
+               controladd(c, session[s].far, session[s].tunnel); // send the message
        }
 
        if (!session[s].die)
@@ -1578,12 +1636,13 @@ void sessionshutdown(sessionidt s, char *reason, int result, int error)
        cluster_send_session(s);
 }
 
-void sendipcp(tunnelidt t, sessionidt s)
+void sendipcp(sessionidt s, tunnelidt t)
 {
-       uint8_t buf[MAXCONTROL];
+       uint8_t buf[MAXETHER];
        uint8_t *q;
 
        CSTAT(sendipcp);
+       LOG(3, s, t, "IPCP: send ConfigReq\n");
 
        if (!session[s].unique_id)
        {
@@ -1591,7 +1650,7 @@ void sendipcp(tunnelidt t, sessionidt s)
                session[s].unique_id = last_id;
        }
 
-       q = makeppp(buf,sizeof(buf), 0, 0, t, s, PPPIPCP);
+       q = makeppp(buf, sizeof(buf), 0, 0, s, t, PPPIPCP);
        if (!q) return;
 
        *q = ConfigReq;
@@ -1606,14 +1665,15 @@ void sendipcp(tunnelidt t, sessionidt s)
        tunnelsend(buf, 10 + (q - buf), t); // send it
 }
 
-void sendipv6cp(tunnelidt t, sessionidt s)
+void sendipv6cp(sessionidt s, tunnelidt t)
 {
-       uint8_t buf[MAXCONTROL];
+       uint8_t buf[MAXETHER];
        uint8_t *q;
 
        CSTAT(sendipv6cp);
+       LOG(3, s, t, "IPV6CP: send ConfigReq\n");
 
-       q = makeppp(buf,sizeof(buf), 0, 0, t, s, PPPIPV6CP);
+       q = makeppp(buf, sizeof(buf), 0, 0, s, t, PPPIPV6CP);
        if (!q) return;
 
        *q = ConfigReq;
@@ -1753,7 +1813,7 @@ static void tunnelshutdown(tunnelidt t, char *reason, int result, int error, cha
                        control16(c, 1, result, 1);
 
                control16(c, 9, t, 1);          // assigned tunnel (our end)
-               controladd(c, t, 0);            // send the message
+               controladd(c, 0, t);            // send the message
        }
 }
 
@@ -1824,12 +1884,16 @@ void processudp(uint8_t *buf, int len, struct sockaddr_in *addr)
                return;
        }
        l -= (p - buf);
+
+       // used to time out old tunnels
+       if (t && tunnel[t].state == TUNNELOPEN)
+               tunnel[t].lastrec = time_now;
+
        if (*buf & 0x80)
        {                          // control
                uint16_t message = 0xFFFF;      // message type
                uint8_t fatal = 0;
                uint8_t mandatory = 0;
-               uint8_t authtype = 0;           // proxy auth type
                uint16_t asession = 0;          // assigned session
                uint32_t amagic = 0;            // magic number
                uint8_t aflags = 0;             // flags from last LCF
@@ -1912,9 +1976,6 @@ void processudp(uint8_t *buf, int len, struct sockaddr_in *addr)
                        return;
                }
 
-               // This is used to time out old tunnels
-               tunnel[t].lastrec = time_now;
-
                // check sequence of this message
                {
                        int skip = tunnel[t].window; // track how many in-window packets are still in queue
@@ -2004,7 +2065,7 @@ void processudp(uint8_t *buf, int len, struct sockaddr_in *addr)
                                        uint16_t orig_len;
 
                                        // handle hidden AVPs
-                                       if (!*config->l2tpsecret)
+                                       if (!*config->l2tp_secret)
                                        {
                                                LOG(1, s, t, "Hidden AVP requested, but no L2TP secret.\n");
                                                fatal = flags;
@@ -2214,11 +2275,6 @@ void processudp(uint8_t *buf, int len, struct sockaddr_in *addr)
                                        {
                                                uint16_t atype = ntohs(*(uint16_t *)b);
                                                LOG(4, s, t, "   Proxy Auth Type %d (%s)\n", atype, ppp_auth_type(atype));
-                                               if (atype == 2)
-                                                       authtype = AUTHCHAP;
-                                               else if (atype == 3)
-                                                       authtype = AUTHPAP;
-
                                                break;
                                        }
                                case 30:    // Proxy Authentication Name
@@ -2251,10 +2307,6 @@ void processudp(uint8_t *buf, int len, struct sockaddr_in *addr)
                                                {
                                                        if (*p == 5 && p[1] == 6) // Magic-Number
                                                                amagic = ntohl(*(uint32_t *) (p + 2));
-                                                       else if (*p == 3 && p[1] == 4 && *(uint16_t *) (p + 2) == htons(PPPPAP)) // Authentication-Protocol (PAP)
-                                                               authtype = AUTHPAP;
-                                                       else if (*p == 3 && p[1] == 5 && *(uint16_t *) (p + 2) == htons(PPPCHAP) && p[4] == 5) // Authentication-Protocol (CHAP)
-                                                               authtype = AUTHCHAP;
                                                        else if (*p == 7) // Protocol-Field-Compression
                                                                aflags |= SESSIONPFC;
                                                        else if (*p == 8) // Address-and-Control-Field-Compression
@@ -2302,10 +2354,10 @@ void processudp(uint8_t *buf, int len, struct sockaddr_in *addr)
                                                controlt *c = controlnew(2); // sending SCCRP
                                                control16(c, 2, version, 1); // protocol version
                                                control32(c, 3, 3, 1); // framing
-                                               controls(c, 7, tunnel[t].hostname, 1); // host name (TBA)
+                                               controls(c, 7, hostname, 1); // host name
                                                if (chapresponse) controlb(c, 13, chapresponse, 16, 1); // Challenge response
                                                control16(c, 9, t, 1); // assigned tunnel
-                                               controladd(c, t, 0); // send the resply
+                                               controladd(c, 0, t); // send the resply
                                        }
                                        else
                                        {
@@ -2353,7 +2405,7 @@ void processudp(uint8_t *buf, int len, struct sockaddr_in *addr)
                                                session[s].last_packet = time_now;
                                                LOG(3, s, t, "New session (%d/%d)\n", tunnel[t].far, session[s].far);
                                                control16(c, 14, s, 1); // assigned session
-                                               controladd(c, t, asession); // send the reply
+                                               controladd(c, asession, t); // send the reply
 
                                                strncpy(session[s].called, called, sizeof(session[s].called) - 1);
                                                strncpy(session[s].calling, calling, sizeof(session[s].calling) - 1);
@@ -2376,7 +2428,7 @@ void processudp(uint8_t *buf, int len, struct sockaddr_in *addr)
                                                else
                                                        control16(c, 1, 2, 7); // shutting down, try another
 
-                                               controladd(c, t, asession); // send the message
+                                               controladd(c, asession, t); // send the message
                                        }
                                        return;
                                case 11:      // ICRP
@@ -2386,20 +2438,17 @@ void processudp(uint8_t *buf, int len, struct sockaddr_in *addr)
                                        if (amagic == 0) amagic = time_now;
                                        session[s].magic = amagic; // set magic number
                                        session[s].l2tp_flags = aflags; // set flags received
-                                       LOG(3, s, t, "Magic %X Flags %X\n", amagic, aflags);
+                                       session[s].mru = PPPMTU; // default
                                        controlnull(t); // ack
 
-                                       // proxy authentication type is not supported
-                                       if (!(config->radius_authtypes & authtype))
-                                               authtype = config->radius_authprefer;
-
                                        // start LCP
-                                       sendlcp(t, s, authtype);
                                        sess_local[s].lcp.restart = time_now + config->ppp_restart_time;
                                        sess_local[s].lcp.conf_sent = 1;
                                        sess_local[s].lcp.nak_sent = 0;
-                                       sess_local[s].lcp_authtype = authtype;
+                                       sess_local[s].lcp_authtype = config->radius_authprefer;
+                                       sess_local[s].ppp_mru = MRU;
                                        session[s].ppp.lcp = RequestSent;
+                                       sendlcp(s, t);
 
                                        break;
                                case 14:      // CDN
@@ -2427,7 +2476,7 @@ void processudp(uint8_t *buf, int len, struct sockaddr_in *addr)
        }
        else
        {                          // data
-               uint16_t prot;
+               uint16_t proto;
 
                LOG_HEX(5, "Receive Tunnel Data", p, l);
                if (l > 2 && p[0] == 0xFF && p[1] == 0x03)
@@ -2443,12 +2492,12 @@ void processudp(uint8_t *buf, int len, struct sockaddr_in *addr)
                }
                if (*p & 1)
                {
-                       prot = *p++;
+                       proto = *p++;
                        l--;
                }
                else
                {
-                       prot = ntohs(*(uint16_t *) p);
+                       proto = ntohs(*(uint16_t *) p);
                        p += 2;
                        l -= 2;
                }
@@ -2468,43 +2517,43 @@ void processudp(uint8_t *buf, int len, struct sockaddr_in *addr)
                        return;
                }
 
-               if (prot == PPPPAP)
+               if (proto == PPPPAP)
                {
                        session[s].last_packet = time_now;
                        if (!config->cluster_iam_master) { master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port); return; }
-                       processpap(t, s, p, l);
+                       processpap(s, t, p, l);
                }
-               else if (prot == PPPCHAP)
+               else if (proto == PPPCHAP)
                {
                        session[s].last_packet = time_now;
                        if (!config->cluster_iam_master) { master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port); return; }
-                       processchap(t, s, p, l);
+                       processchap(s, t, p, l);
                }
-               else if (prot == PPPLCP)
+               else if (proto == PPPLCP)
                {
                        session[s].last_packet = time_now;
                        if (!config->cluster_iam_master) { master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port); return; }
-                       processlcp(t, s, p, l);
+                       processlcp(s, t, p, l);
                }
-               else if (prot == PPPIPCP)
+               else if (proto == PPPIPCP)
                {
                        session[s].last_packet = time_now;
                        if (!config->cluster_iam_master) { master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port); return; }
-                       processipcp(t, s, p, l);
+                       processipcp(s, t, p, l);
                }
-               else if (prot == PPPIPV6CP)
+               else if (proto == PPPIPV6CP && config->ipv6_prefix.s6_addr[0])
                {
                        session[s].last_packet = time_now;
                        if (!config->cluster_iam_master) { master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port); return; }
-                       processipv6cp(t, s, p, l);
+                       processipv6cp(s, t, p, l);
                }
-               else if (prot == PPPCCP)
+               else if (proto == PPPCCP)
                {
                        session[s].last_packet = time_now;
                        if (!config->cluster_iam_master) { master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port); return; }
-                       processccp(t, s, p, l);
+                       processccp(s, t, p, l);
                }
-               else if (prot == PPPIP)
+               else if (proto == PPPIP)
                {
                        if (session[s].die)
                        {
@@ -2519,15 +2568,10 @@ void processudp(uint8_t *buf, int len, struct sockaddr_in *addr)
                                return;
                        }
 
-                       processipin(t, s, p, l);
+                       processipin(s, t, p, l);
                }
-               else if (prot == PPPIPV6)
+               else if (proto == PPPIPV6 && config->ipv6_prefix.s6_addr[0])
                {
-                       if (!config->ipv6_prefix.s6_addr[0])
-                       {
-                               LOG(1, s, t, "IPv6 not configured; yet received IPv6 packet. Ignoring.\n");
-                               return;
-                       }
                        if (session[s].die)
                        {
                                LOG(4, s, t, "Session %d is closing.  Don't process PPP packets\n", s);
@@ -2541,12 +2585,38 @@ void processudp(uint8_t *buf, int len, struct sockaddr_in *addr)
                                return;
                        }
 
-                       processipv6in(t, s, p, l);
+                       processipv6in(s, t, p, l);
+               }
+               else if (session[s].ppp.lcp == Opened)
+               {
+                       uint8_t buf[MAXETHER];
+                       uint8_t *q;
+                       int mru = session[s].mru;
+                       if (mru > sizeof(buf)) mru = sizeof(buf);
+
+                       l += 6;
+                       if (l > mru) l = mru;
+
+                       q = makeppp(buf, sizeof(buf), 0, 0, s, t, proto);
+                       if (!q) return;
+
+                       *q = CodeRej;
+                       *(q + 1) = ++sess_local[s].lcp_ident;
+                       *(uint16_t *)(q + 2) = l;
+                       *(uint16_t *)(q + 4) = htons(proto);
+                       memcpy(q + 6, p, l - 6);
+
+                       if (proto == PPPIPV6CP)
+                               LOG(3, s, t, "LCP: send ProtocolRej (IPV6CP: not configured)\n");
+                       else
+                               LOG(2, s, t, "LCP: sent ProtocolRej (0x%04X: unsupported)\n", proto);
+
+                       tunnelsend(buf, l + (q - buf), t);
                }
                else
                {
-                       STAT(tunnel_rx_errors);
-                       LOG(1, s, t, "Unknown PPP protocol %04X\n", prot);
+                       LOG(2, s, t, "Unknown PPP protocol 0x%04X received in LCP %s state\n",
+                               proto, ppp_state(session[s].ppp.lcp));
                }
        }
 }
@@ -2657,10 +2727,10 @@ static void regular_cleanups(double period)
                        }
                }
                // Send hello
-               if (tunnel[t].state == TUNNELOPEN && tunnel[t].lastrec < TIME + 600)
+               if (tunnel[t].state == TUNNELOPEN && (time_now - tunnel[t].lastrec) > 60)
                {
                        controlt *c = controlnew(6); // sending HELLO
-                       controladd(c, t, 0); // send the message
+                       controladd(c, 0, t); // send the message
                        LOG(3, 0, t, "Sending HELLO message\n");
                        t_actions++;
                }
@@ -2730,7 +2800,7 @@ static void regular_cleanups(double period)
                                        LOG(3, s, session[s].tunnel, "No ACK for LCP ConfigReq... resending\n");
                                        sess_local[s].lcp.restart = time_now + config->ppp_restart_time;
                                        sess_local[s].lcp.conf_sent++;
-                                       sendlcp(t, s, sess_local[s].lcp_authtype);
+                                       sendlcp(s, session[s].tunnel);
                                        change_state(s, lcp, next_state);
                                }
                                else
@@ -2761,7 +2831,7 @@ static void regular_cleanups(double period)
                                        LOG(3, s, session[s].tunnel, "No ACK for IPCP ConfigReq... resending\n");
                                        sess_local[s].ipcp.restart = time_now + config->ppp_restart_time;
                                        sess_local[s].ipcp.conf_sent++;
-                                       sendipcp(t, s);
+                                       sendipcp(s, session[s].tunnel);
                                        change_state(s, ipcp, next_state);
                                }
                                else
@@ -2792,7 +2862,7 @@ static void regular_cleanups(double period)
                                        LOG(3, s, session[s].tunnel, "No ACK for IPV6CP ConfigReq... resending\n");
                                        sess_local[s].ipv6cp.restart = time_now + config->ppp_restart_time;
                                        sess_local[s].ipv6cp.conf_sent++;
-                                       sendipv6cp(t, s);
+                                       sendipv6cp(s, session[s].tunnel);
                                        change_state(s, ipv6cp, next_state);
                                }
                                else
@@ -2820,7 +2890,7 @@ static void regular_cleanups(double period)
                                        LOG(3, s, session[s].tunnel, "No ACK for CCP ConfigReq... resending\n");
                                        sess_local[s].ccp.restart = time_now + config->ppp_restart_time;
                                        sess_local[s].ccp.conf_sent++;
-                                       sendccp(t, s);
+                                       sendccp(s, session[s].tunnel);
                                        change_state(s, ccp, next_state);
                                }
                                else
@@ -2845,9 +2915,9 @@ static void regular_cleanups(double period)
                // No data in ECHO_TIMEOUT seconds, send LCP ECHO
                if (session[s].ppp.phase >= Establish && (time_now - session[s].last_packet >= ECHO_TIMEOUT))
                {
-                       uint8_t b[MAXCONTROL] = {0};
+                       uint8_t b[MAXETHER];
 
-                       uint8_t *q = makeppp(b, sizeof(b), 0, 0, session[s].tunnel, s, PPPLCP);
+                       uint8_t *q = makeppp(b, sizeof(b), 0, 0, s, session[s].tunnel, PPPLCP);
                        if (!q) continue;
 
                        *q = EchoReq;
@@ -3481,6 +3551,7 @@ static void initdata(int optdebug, char *optconfig)
        config->debug = optdebug;
        config->num_tbfs = MAXTBFS;
        config->rl_rate = 28; // 28kbps
+       config->cluster_mcast_ttl = 1;
        config->cluster_master_min_adv = 1;
        config->ppp_restart_time = 3;
        config->ppp_max_configure = 10;
@@ -4154,7 +4225,7 @@ static void build_chap_response(uint8_t *challenge, uint8_t id, uint16_t challen
        MD5_CTX ctx;
        *challenge_response = NULL;
 
-       if (!*config->l2tpsecret)
+       if (!*config->l2tp_secret)
        {
                LOG(0, 0, 0, "LNS requested CHAP authentication, but no l2tp secret is defined\n");
                return;
@@ -4166,7 +4237,7 @@ static void build_chap_response(uint8_t *challenge, uint8_t id, uint16_t challen
 
        MD5_Init(&ctx);
        MD5_Update(&ctx, &id, 1);
-       MD5_Update(&ctx, config->l2tpsecret, strlen(config->l2tpsecret));
+       MD5_Update(&ctx, config->l2tp_secret, strlen(config->l2tp_secret));
        MD5_Update(&ctx, challenge, challenge_length);
        MD5_Final(*challenge_response, &ctx);
 
@@ -4233,6 +4304,17 @@ static void update_config()
                setbuf(log_stream, NULL);
        }
 
+#define L2TP_HDRS              (20+8+6+4)      // L2TP data encaptulation: ip + udp + l2tp (data) + ppp (inc hdlc)
+#define TCP_HDRS               (20+20)         // TCP encapsulation: ip + tcp
+
+       if (config->l2tp_mtu <= 0)              config->l2tp_mtu = PPPMTU;
+       else if (config->l2tp_mtu < MINMTU)     config->l2tp_mtu = MINMTU;
+       else if (config->l2tp_mtu > MAXMTU)     config->l2tp_mtu = MAXMTU;
+
+       // reset MRU/MSS globals
+       MRU = config->l2tp_mtu - L2TP_HDRS;
+       MSS = MRU - TCP_HDRS;
+
        // Update radius
        config->numradiusservers = 0;
        for (i = 0; i < MAXRADSERVER; i++)
@@ -4400,7 +4482,7 @@ static void read_config_file()
        update_config();
 }
 
-int sessionsetup(tunnelidt t, sessionidt s)
+int sessionsetup(sessionidt s, tunnelidt t)
 {
        // A session now exists, set it up
        in_addr_t ip;
@@ -4479,7 +4561,7 @@ int sessionsetup(tunnelidt t, sessionidt s)
        }
 
        sess_local[s].lcp_authtype = 0; // RADIUS authentication complete
-       lcp_open(t, s); // transition to Network phase and send initial IPCP
+       lcp_open(s, t); // transition to Network phase and send initial IPCP
 
        // Run the plugin's against this new session.
        {
@@ -5131,7 +5213,7 @@ static void unhide_value(uint8_t *value, size_t len, uint16_t type, uint8_t *vec
        // Compute initial pad
        MD5_Init(&ctx);
        MD5_Update(&ctx, (unsigned char *) &m, 2);
-       MD5_Update(&ctx, config->l2tpsecret, strlen(config->l2tpsecret));
+       MD5_Update(&ctx, config->l2tp_secret, strlen(config->l2tp_secret));
        MD5_Update(&ctx, vector, vec_len);
        MD5_Final(digest, &ctx);
 
@@ -5144,7 +5226,7 @@ static void unhide_value(uint8_t *value, size_t len, uint16_t type, uint8_t *vec
                if (d >= sizeof(digest))
                {
                        MD5_Init(&ctx);
-                       MD5_Update(&ctx, config->l2tpsecret, strlen(config->l2tpsecret));
+                       MD5_Update(&ctx, config->l2tp_secret, strlen(config->l2tp_secret));
                        MD5_Update(&ctx, last, sizeof(digest));
                        MD5_Final(digest, &ctx);