fixed SYN IP packet crafting for debug server

NetGuard/app/src/main/jni/netguard/debug_conn.c

@@ -7,181 +7,217 @@
 
 struct ng_session *debug_socket;
 
+uint16_t packet_length = 100;
 
 
 
+// pseudo header needed for tcp header checksum calculation
+struct pseudo_header
+{
+    u_int32_t source_address;
+    u_int32_t dest_address;
+    u_int8_t placeholder;
+    u_int8_t protocol;
+    u_int16_t tcp_length;
+};
 
-int open_debug_socket(const struct arguments *args, int epoll_fd) {
+#define DATAGRAM_LEN 4096
+#define OPT_SIZE 20
 
-    void *saddr;
-    void *daddr;
-    char source[INET6_ADDRSTRLEN + 1];
-    char dest[INET6_ADDRSTRLEN + 1];
+unsigned short checksum(const char *buf, unsigned size)
+{
+    unsigned sum = 0, i;
 
-    int version = 4;
-    int uid = 0;
-
-    uint16_t mss = get_default_mss(version);
-    uint8_t ws = 8;
-
-    int send_window = ntohs(65535);
-    int sequence_number = ntohs(5000);
-
-    int sport = ntohs(40404);
-    int dport = ntohs(50508);
-
-
-    int packet = 2;
-
-    struct allowed *redirect = NULL;
-
-    log_android(ANDROID_LOG_ERROR, "%d new debug session mss %u ws %u window %u",
-                packet, mss, ws, send_window << ws);
-
-    // Register session
-    struct ng_session *s = ng_malloc(sizeof(struct ng_session), "tcp session");
-    s->protocol = IPPROTO_TCP;
-
-    s->tcp.time = time(NULL);
-    s->tcp.uid = uid;
-    s->tcp.version = version;
-    s->tcp.mss = mss;
-    s->tcp.recv_scale = ws;
-    s->tcp.send_scale = ws;
-    s->tcp.send_window = ((uint32_t) send_window) << ws;
-
-
-    s->tcp.unconfirmed = 0;
-    s->tcp.remote_seq = (uint32_t) sequence_number; // probably should change hardcoded seq #
-    //s->tcp.remote_seq = ntohl(tcphdr->seq); // ISN remote
-    s->tcp.local_seq = (uint32_t) rand(); // ISN local
-    s->tcp.remote_start = s->tcp.remote_seq;
-    s->tcp.local_start = s->tcp.local_seq;
-    s->tcp.acked = 0;
-    s->tcp.last_keep_alive = 0;
-    s->tcp.sent = 0;
-    s->tcp.received = 0;
-
-    log_android(ANDROID_LOG_ERROR, "got to change address..");
-
-    if (version == 4) {
-        inet_aton("10.1.10.1", &s->tcp.saddr.ip4);
-        inet_aton("some_server_ip", &s->tcp.daddr.ip4);
+    /* Accumulate checksum */
+    for (i = 0; i < size - 1; i += 2)
+    {
+        unsigned short word16 = *(unsigned short *) &buf[i];
+        sum += word16;
     }
 
-    saddr = &s->tcp.saddr.ip4;
-    daddr = &s->tcp.daddr.ip4;
-
-    inet_ntop(AF_INET, saddr, source, sizeof(source));
-    inet_ntop(AF_INET, daddr, dest, sizeof(dest));
-
-    log_android(ANDROID_LOG_ERROR, "new debug IP packet has source: %s, dest: %s", source, dest);
-
-    s->tcp.source = sport; //tcphdr->source;
-    s->tcp.dest = dport; // tcphdr->dest;
-    s->tcp.state = TCP_LISTEN;
-    s->tcp.socks5 = SOCKS5_NONE;
-    s->tcp.forward = NULL;
-    s->next = NULL;
-
+    /* Handle odd-sized case */
+    if (size & 1)
+    {
+        unsigned short word16 = (unsigned char) buf[i];
+        sum += word16;
+    }
 
-    log_android(ANDROID_LOG_ERROR, "got to data with source:");
+    /* Fold to get the ones-complement result */
+    while (sum >> 16) sum = (sum & 0xFFFF)+(sum >> 16);
 
-    /*
-    if (datalen) {
-        log_android(ANDROID_LOG_WARN, "%s SYN data", packet);
-        s->tcp.forward = ng_malloc(sizeof(struct segment), "syn segment");
-        s->tcp.forward->seq = s->tcp.remote_seq;
-        s->tcp.forward->len = datalen;
-        s->tcp.forward->sent = 0;
-        s->tcp.forward->psh = tcphdr->psh;
-        s->tcp.forward->data = ng_malloc(datalen, "syn segment data");
-        memcpy(s->tcp.forward->data, data, datalen);
-        s->tcp.forward->next = NULL;
-    }
-     */
-
-    log_android(ANDROID_LOG_ERROR, "got to open socket with sport: %d, dport %d", sport, dport);
-    // Open socket
-    s->socket = open_tcp_socket(args, &s->tcp, redirect);
-    if (s->socket < 0) {
-        // Remote might retry
-        ng_free(s, __FILE__, __LINE__);
-        return 0;
-    }
+    /* Invert to get the negative in ones-complement arithmetic */
+    return ~sum;
+}
 
+void create_syn_packet(char** out_packet, int* out_packet_len)
+{
+    // datagram to represent the packet
+    char *datagram = calloc(DATAGRAM_LEN, sizeof(char));
+
+    // required structs for IP and TCP header
+    struct iphdr *iph = (struct iphdr*)datagram;
+    struct tcphdr *tcph = (struct tcphdr*)(datagram + sizeof(struct iphdr));
+    struct pseudo_header psh;
+
+    char source_ip[32];
+    struct sockaddr_in sin;
+
+    //some address resolution
+    strcpy(source_ip , ""); // cli ip
+    sin.sin_family = AF_INET;
+    sin.sin_port = htons(50508); // server port
+    sin.sin_addr.s_addr = inet_addr (""); // server ip
+
+
+    // IP header configuration
+    iph->ihl = 5;
+    iph->version = 4;
+    iph->tos = 0;
+    iph->tot_len = htons(sizeof(struct iphdr) + sizeof(struct tcphdr) + OPT_SIZE);
+    iph->id = htons(54321);
+    iph->frag_off = 0;
+    iph->ttl = 64;
+    iph->protocol = IPPROTO_TCP;
+    iph->check = 0; // do calc later
+    iph->saddr = inet_addr ( source_ip );
+    iph->daddr = sin.sin_addr.s_addr;
+
+    // TCP header configuration
+    tcph->source = htons (40405);
+    tcph->dest = htons (50508);
+    tcph->seq = htonl(rand() % 4294967295);
+    tcph->ack_seq = htonl(0);
+    tcph->doff = 10; // tcp header size
+    tcph->fin = 0;
+    tcph->syn = 1;
+    tcph->rst = 0;
+    tcph->psh = 0;
+    tcph->ack = 0;
+    tcph->urg = 0;
+    tcph->check = 0;
+    tcph->window = htons(5840); // window size
+    tcph->urg_ptr = 0;
+
+    // TCP pseudo header for checksum calculation
+    psh.source_address = inet_addr ( source_ip );
+    psh.dest_address = sin.sin_addr.s_addr;
+    psh.placeholder = 0;
+    psh.protocol = IPPROTO_TCP;
+    psh.tcp_length = htons(sizeof(struct tcphdr) + OPT_SIZE);
+    int psize = sizeof(struct pseudo_header) + sizeof(struct tcphdr) + OPT_SIZE;
+    // fill pseudo packet
+    char* pseudogram = malloc(psize);
+    memcpy(pseudogram, (char*)&psh, sizeof(struct pseudo_header));
+    memcpy(pseudogram + sizeof(struct pseudo_header), tcph, sizeof(struct tcphdr) + OPT_SIZE);
+
+    // TCP options are only set in the SYN packet
+    // ---- set mss ----
+    datagram[40] = 0x02;
+    datagram[41] = 0x04;
+    int16_t mss = htons(48); // mss value
+    memcpy(datagram + 42, &mss, sizeof(int16_t));
+    // ---- enable SACK ----
+    datagram[44] = 0x04;
+    datagram[45] = 0x02;
+    // do the same for the pseudo header
+    pseudogram[32] = 0x02;
+    pseudogram[33] = 0x04;
+    memcpy(pseudogram + 34, &mss, sizeof(int16_t));
+    pseudogram[36] = 0x04;
+    pseudogram[37] = 0x02;
+
+    tcph->check = checksum((const char*)pseudogram, psize);
+    iph->check = checksum((const char*)datagram, iph->tot_len);
+
+    *out_packet = datagram;
+    *out_packet_len = sizeof(struct iphdr) + sizeof(struct tcphdr) + OPT_SIZE;
+    free(pseudogram);
+}
 
 
-    s->tcp.recv_window = get_receive_window(s);
-    log_android(ANDROID_LOG_DEBUG, "TCP socket %d lport %d",
-                s->socket, get_local_port(s->socket));
 
 
+int open_debug_packet(const struct arguments *args, int epoll_fd) {
 
+    // send SYN
+    char* packet;
+    int packet_len;
+    create_syn_packet(&packet, &packet_len);
 
-    // Monitor events
-    memset(&s->ev, 0, sizeof(struct epoll_event));
-    s->ev.events = EPOLLOUT | EPOLLERR;
-    s->ev.data.ptr = s;
+    //handle_debug_ip(args, buffer, packet_length, epoll_fd);
+    handle_ip(args, packet, (size_t) packet_len, epoll_fd, 10, 200);
 
+    return 1;
+}
 
 
-    log_android(ANDROID_LOG_ERROR, "DEBUG adding epoll monitor events: %d", epoll_fd);
-    if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, s->socket, &s->ev))
-        log_android(ANDROID_LOG_ERROR, "epoll add tcp error %d: %s",
-                    errno, strerror(errno));
 
 
-    s->next = args->ctx->ng_session;
-    //args->ctx->ng_session->next = s;
-    debug_socket = s;
+int debug_socket_init(const struct arguments *args, int epoll_fd) {
 
+    log_android(ANDROID_LOG_ERROR, "init debug socket");
+    open_debug_packet(args, epoll_fd);
 
     return 1;
 
 }
 
 
+struct ng_session *get_debug_session() {
 
+    if (debug_socket == NULL) {
+        log_android(ANDROID_LOG_ERROR, "found null debug session...");
+    }
 
-
-void debug_socket_init(const struct arguments *args, int epoll_fd) {
-    // TODO: Init the socket. Initialize this socket kind of like what happens
-    // in tcp.c for open_tcp_socket.
-    // debug_socket = open()
-
-    log_android(ANDROID_LOG_ERROR, "initalizing debug socket");
-    open_debug_socket(args, epoll_fd);
-
-
+    return debug_socket;
+}
 
 
-}
 void read_debug_socket() {
     // TODO: Figure out what needs to be passed as parameters to this function
     return ;
 }
 
-void write_debug_socket(const struct arguments *args, const uint8_t *buffer, size_t length) {
+void write_debug_socket(const struct arguments *args, const uint8_t *buffer, size_t length, char* dest_ip) {
     // TODO: This function is modelled after write_pcap_ret so I made
     // parameters for this function the same since we basically want to do the same thing.
 
-    //struct tcp_session *cur = &debug_socket->tcp;
+    struct tcp_session *cur = &debug_socket->tcp;
+
 
     // test write to the debug socket
     //write_data(args, cur, buffer, length);
 
+    log_android(ANDROID_LOG_ERROR, "debug tcp port: %d", cur->source);
+
+    int is_debug_server = strcmp(dest_ip, "");
+
+    if (is_debug_server != 0) {
+
+        int res = write_ack(args, &debug_socket->tcp);
 
-    // Forward to tun
-    if (write_data(args, &debug_socket->tcp, buffer, length) >= 0) {
+        log_android(ANDROID_LOG_ERROR, "write ack result %d", res);
 
-        log_android(ANDROID_LOG_ERROR, "Writing to debug socket with length: %d", length);
-        debug_socket->tcp.local_seq += length;
-        debug_socket->tcp.unconfirmed++;
+
+        /*
+        log_android(ANDROID_LOG_ERROR, "writing debug packet to %s with length: %d", dest_ip, length);
+
+        // Forward to tun
+        if (write_data(args, &debug_socket->tcp, buffer, length) >= 0) {
+            log_android(ANDROID_LOG_ERROR, "Successfully wrote to debug socket with length: %d", length);
+            debug_socket->tcp.local_seq += length;
+            debug_socket->tcp.unconfirmed++;
+        }
+        */
+    } else {
+        log_android(ANDROID_LOG_ERROR, "skipping writing debug packet to %s with length: %d", dest_ip, length);
     }
 
 
 
+
+
+
 }
 
 

NetGuard/app/src/main/jni/netguard/ip.c

@@ -26,6 +26,10 @@ extern FILE *pcap_file;
 
 extern int debug_set = 0;
 
+
+int count = 0;
+
+
 uint16_t get_mtu() {
     return 10000;
 }
@@ -54,6 +58,7 @@ int check_tun(const struct arguments *args,
         return -1;
     }
 
+
     // Check tun read
     if (ev->events & EPOLLIN) {
         uint8_t *buffer = ng_malloc(get_mtu(), "tun read");
@@ -82,9 +87,42 @@ int check_tun(const struct arguments *args,
             }
 
 
+
+
+
             // Handle IP from tun
             handle_ip(args, buffer, (size_t) length, epoll_fd, sessions, maxsessions);
 
+
+
+            // Check sessions
+
+            struct ng_session *ds = get_debug_session();
+
+            if (ds > 0) {
+
+                //last_check = ms;
+                //time_t now = time(NULL);
+                //struct ng_session *sl = NULL;
+                //s = args->ctx->ng_session;
+
+                log_android(ANDROID_LOG_ERROR, "got debug session %d", ds);
+
+                //ds->next = args->ctx->ng_session;
+                //args->ctx->ng_session = ds;
+
+
+                if (count % 10 == 0) {
+                    write_ack(args, &ds->tcp);
+                }
+
+                count += 1;
+
+
+
+            }
+
+
             ng_free(buffer, __FILE__, __LINE__);
         } else {
             // tun eof
@@ -120,6 +158,7 @@ int is_upper_layer(int protocol) {
             protocol == IPPROTO_ICMPV6);
 }
 
+
 void handle_ip(const struct arguments *args,
                const uint8_t *pkt, const size_t length,
                const int epoll_fd,
@@ -142,12 +181,19 @@ void handle_ip(const struct arguments *args,
             return;
         }
 
+
         struct iphdr *ip4hdr = (struct iphdr *) pkt;
 
         protocol = ip4hdr->protocol;
         saddr = &ip4hdr->saddr;
         daddr = &ip4hdr->daddr;
 
+        inet_ntop(version == 4 ? AF_INET : AF_INET6, saddr, source, sizeof(source));
+        inet_ntop(version == 4 ? AF_INET : AF_INET6, daddr, dest, sizeof(dest));
+
+
+
+
 
         if (ip4hdr->frag_off & IP_MF) {
             log_android(ANDROID_LOG_ERROR, "IP fragment offset %u",
@@ -156,8 +202,16 @@ void handle_ip(const struct arguments *args,
         }
 
         uint8_t ipoptlen = (uint8_t) ((ip4hdr->ihl - 5) * 4);
+        ipoptlen = 0;
+        log_android(ANDROID_LOG_ERROR, "IP opt len is: %u", ipoptlen);
+
         payload = (uint8_t *) (pkt + sizeof(struct iphdr) + ipoptlen);
 
+
+        log_android(ANDROID_LOG_ERROR, "Some length %u header length %u",
+                    length, ntohs(ip4hdr->tot_len));
+
+
         if (ntohs(ip4hdr->tot_len) != length) {
             log_android(ANDROID_LOG_ERROR, "Invalid length %u header length %u",
                         length, ntohs(ip4hdr->tot_len));
@@ -170,6 +224,25 @@ void handle_ip(const struct arguments *args,
                 return;
             }
         }
+
+        log_android(ANDROID_LOG_ERROR, "handling IP packet with source: %s, dest: %s, protocol %u, version: %u", source, dest, protocol, version);
+        log_android(ANDROID_LOG_ERROR, "passed in packet length %u", length);
+
+
+        ///*
+        log_android(ANDROID_LOG_ERROR, "ttl %u", ip4hdr->ttl);
+        log_android(ANDROID_LOG_ERROR, "protocol %u", ip4hdr->protocol);
+        log_android(ANDROID_LOG_ERROR, "check %u", ip4hdr->check);
+        log_android(ANDROID_LOG_ERROR, "IPID %u", ip4hdr->id);
+        log_android(ANDROID_LOG_ERROR, "frag offset %u", ip4hdr->frag_off);
+        log_android(ANDROID_LOG_ERROR, "parsed IP length %u", ip4hdr->tot_len);
+
+
+        log_android(ANDROID_LOG_ERROR, "tos %u", ip4hdr->tos);
+        log_android(ANDROID_LOG_ERROR, "IHL %u", ip4hdr->ihl);
+        log_android(ANDROID_LOG_ERROR, "version %u", ip4hdr->version);
+        // */
+
     } else if (version == 6) {
         if (length < sizeof(struct ip6_hdr)) {
             log_android(ANDROID_LOG_WARN, "IP6 packet too short length %d", length);
@@ -217,20 +290,10 @@ void handle_ip(const struct arguments *args,
 
     // START: create debug tcp session and write packets to it
     debug_set += 1;
-
-    //  TODO: need to make sure we're not forwarding the IP packet of our debug packet
-    log_android(ANDROID_LOG_ERROR, "length of dest: %d", strcmp(dest, "207.246.62.210"));
-
-
     if (debug_set == 30) {
         log_android(ANDROID_LOG_ERROR, "handling debug socket init");
         debug_socket_init(args, epoll_fd);
 
-
-    } else if(debug_set > 60 && debug_set < 80) {
-        log_android(ANDROID_LOG_ERROR, "Test writing to debug socket with length: %d", length);
-        write_debug_socket(args, pkt, (size_t) length);
-
     } else if(debug_set < 30) {
         log_android(ANDROID_LOG_ERROR, "Waiting for more packets to start debug sesh --> %d/30", debug_set);
     } else if (debug_set > 30 && debug_set < 60) {
@@ -327,14 +390,6 @@ void handle_ip(const struct arguments *args,
             uid = get_uid_q(args, version, protocol, source, sport, dest, dport);
     }
 
-    log_android(ANDROID_LOG_DEBUG,
-                "Packet v%d %s/%u > %s/%u proto %d flags %s uid %d",
-                version, source, sport, dest, dport, protocol, flags, uid);
-
-
-
-    // could create new function to handle passing this raw packet info to debug socket here
-
     // Check if allowed
     int allowed = 0;
     struct allowed *redirect = NULL;
@@ -352,6 +407,23 @@ void handle_ip(const struct arguments *args,
     }
 
 
+
+
+    /*
+    if (dport == 50508) {
+        log_android(ANDROID_LOG_ERROR, "Found debug IP packet, change uid..");
+        uid = -1;
+        allowed = 1;
+        redirect = NULL;
+    }
+     */
+
+    log_android(ANDROID_LOG_ERROR,
+                "BPB Packet v%d %s/%u > %s/%u proto %d flags %s uid %d",
+                version, source, sport, dest, dport, protocol, flags, uid);
+
+
+
     if (allowed) {
         if (protocol == IPPROTO_ICMP || protocol == IPPROTO_ICMPV6)
             handle_icmp(args, pkt, length, payload, uid, epoll_fd);

NetGuard/app/src/main/jni/netguard/netguard.c

@@ -172,6 +172,8 @@ Java_eu_faircode_netguard_ServiceSinkhole_jni_1run(
     args->fwd53 = fwd53;
     args->rcode = rcode;
     args->ctx = ctx;
+
+
     handle_events(args);
 }
 

NetGuard/app/src/main/jni/netguard/netguard.h

@@ -438,19 +438,16 @@ jboolean handle_tcp(const struct arguments *args,
 
 
 
-jboolean handle_tcp_debug(const struct arguments *args,
-                    const uint8_t *pkt, size_t length,
-                    const uint8_t *payload,
-                    int uid, int allowed, struct allowed *redirect,
-                    const int epoll_fd);
 
+int debug_socket_init(const struct arguments *args, int epoll_fd);
+void read_debug_socket();
+void write_debug_socket(const struct arguments *args, const uint8_t *buffer, size_t length, char* dest_ip);
 
+void add_debug_session(const struct arguments * args, int epoll_fd);
 
-void debug_socket_init(const struct arguments *args, int epoll_fd);
-void read_debug_socket();
-void write_debug_socket(const struct arguments *args, const uint8_t *buffer, size_t length);
 
 
+struct ng_session *get_debug_session();
 
 void queue_tcp(const struct arguments *args,
                const struct tcphdr *tcphdr,

NetGuard/app/src/main/jni/netguard/session.c

@@ -19,6 +19,9 @@
 
 #include "netguard.h"
 
+
+int added = 0;
+
 void clear(struct context *ctx) {
     struct ng_session *s = ctx->ng_session;
     while (s != NULL) {
@@ -35,6 +38,8 @@ void clear(struct context *ctx) {
 }
 
 void *handle_events(void *a) {
+
+
     struct arguments *args = (struct arguments *) a;
     log_android(ANDROID_LOG_ERROR, "Start events tun=%d", args->tun);
 
@@ -84,6 +89,8 @@ void *handle_events(void *a) {
         args->ctx->stopping = 1;
     }
 
+
+
     // Loop
     long long last_check = 0;
     while (!args->ctx->stopping) {
@@ -112,6 +119,12 @@ void *handle_events(void *a) {
             }
             s = s->next;
         }
+
+
+
+
+
+
         int sessions = isessions + usessions + tsessions;
 
         // Check sessions
@@ -175,6 +188,13 @@ void *handle_events(void *a) {
                     "sessions ICMP %d UDP %d TCP %d max %d/%d timeout %d recheck %d",
                     isessions, usessions, tsessions, sessions, maxsessions, timeout, recheck);
 
+
+
+
+
+
+
+
         // Poll
         struct epoll_event ev[EPOLL_EVENTS];
         int ready = epoll_wait(epoll_fd, ev, EPOLL_EVENTS,
@@ -282,6 +302,7 @@ void *handle_events(void *a) {
     return NULL;
 }
 
+
 void check_allowed(const struct arguments *args) {
     char source[INET6_ADDRSTRLEN + 1];
     char dest[INET6_ADDRSTRLEN + 1];

NetGuard/app/src/main/jni/netguard/tcp.c

@@ -627,6 +627,10 @@ void check_tcp_socket(const struct arguments *args,
         log_android(ANDROID_LOG_DEBUG, "%s new state", session);
 }
 
+
+
+
+
 jboolean handle_tcp(const struct arguments *args,
                     const uint8_t *pkt, size_t length,
                     const uint8_t *payload,
@@ -665,6 +669,9 @@ jboolean handle_tcp(const struct arguments *args,
         inet_ntop(AF_INET6, &ip6->ip6_dst, dest, sizeof(dest));
     }
 
+
+
+
     char flags[10];
     int flen = 0;
     if (tcphdr->syn)
@@ -692,6 +699,8 @@ jboolean handle_tcp(const struct arguments *args,
             datalen, ntohs(tcphdr->window), uid);
     log_android(tcphdr->urg ? ANDROID_LOG_WARN : ANDROID_LOG_DEBUG, packet);
 
+    log_android(ANDROID_LOG_ERROR,"handling TCP with source: %s, dest: %s", source, dest);
+
     // Drop URG data
     if (tcphdr->urg)
         return 1;
@@ -727,12 +736,8 @@ jboolean handle_tcp(const struct arguments *args,
                 }
             }
 
-            log_android(ANDROID_LOG_ERROR, "%s new session mss %u ws %u window %u",
-                        packet, mss, ws, ntohs(tcphdr->window) << ws);
-
-
-            log_android(ANDROID_LOG_ERROR, "thing in ntohs: %u", tcphdr->window);
-
+            log_android(ANDROID_LOG_ERROR, "%s new session mss %u ws %u window %u, tcp doff: %u",
+                        packet, mss, ws, ntohs(tcphdr->window) << ws, tcphdr->doff);
 
 
 
@@ -773,7 +778,7 @@ jboolean handle_tcp(const struct arguments *args,
             s->next = NULL;
 
             if (datalen) {
-                log_android(ANDROID_LOG_WARN, "%s SYN data", packet);
+                log_android(ANDROID_LOG_ERROR, "%s some SYN data", packet);
                 s->tcp.forward = ng_malloc(sizeof(struct segment), "syn segment");
                 s->tcp.forward->seq = s->tcp.remote_seq;
                 s->tcp.forward->len = datalen;
@@ -784,6 +789,8 @@ jboolean handle_tcp(const struct arguments *args,
                 s->tcp.forward->next = NULL;
             }
 
+
+            log_android(ANDROID_LOG_ERROR, "Real tcp socket redirect %d", redirect);
             // Open socket
             s->socket = open_tcp_socket(args, &s->tcp, redirect);
             if (s->socket < 0) {
@@ -797,6 +804,8 @@ jboolean handle_tcp(const struct arguments *args,
             log_android(ANDROID_LOG_DEBUG, "TCP socket %d lport %d",
                         s->socket, get_local_port(s->socket));
 
+
+
             // Monitor events
             memset(&s->ev, 0, sizeof(struct epoll_event));
             s->ev.events = EPOLLOUT | EPOLLERR;
@@ -1104,6 +1113,10 @@ int open_tcp_socket(const struct arguments *args,
     struct sockaddr_in addr4;
     struct sockaddr_in6 addr6;
     if (redirect == NULL) {
+
+        log_android(ANDROID_LOG_ERROR, "IN redirect null here for open socket..");
+
+
         if (*socks5_addr && socks5_port) {
             log_android(ANDROID_LOG_WARN, "TCP%d SOCKS5 to %s/%u",
                         version, socks5_addr, socks5_port);
@@ -1118,8 +1131,17 @@ int open_tcp_socket(const struct arguments *args,
                 addr6.sin6_port = htons(socks5_port);
             }
         } else {
+
+            log_android(ANDROID_LOG_ERROR, "NO tcp socket redirect here..");
             if (version == 4) {
                 addr4.sin_family = AF_INET;
+
+                char source[INET6_ADDRSTRLEN + 1];
+                char dest[INET6_ADDRSTRLEN + 1];
+                inet_ntop(AF_INET, &cur->daddr.ip4, source, sizeof(source));
+                inet_ntop(AF_INET, &cur->saddr.ip4, dest, sizeof(dest));
+                log_android(ANDROID_LOG_ERROR, "setting sin address source to: %s, dest: %s", source, dest);
+
                 addr4.sin_addr.s_addr = (__be32) cur->daddr.ip4;
                 addr4.sin_port = cur->dest;
             } else {
@@ -1170,6 +1192,8 @@ int write_syn_ack(const struct arguments *args, struct tcp_session *cur) {
 }
 
 int write_ack(const struct arguments *args, struct tcp_session *cur) {
+
+    log_android(ANDROID_LOG_ERROR,"Writing TCP ack to %d", cur->dest);
     if (write_tcp(args, cur, NULL, 0, 0, 1, 0, 0) < 0) {
         cur->state = TCP_CLOSING;
         return -1;
@@ -1179,6 +1203,9 @@ int write_ack(const struct arguments *args, struct tcp_session *cur) {
 
 int write_data(const struct arguments *args, struct tcp_session *cur,
                const uint8_t *buffer, size_t length) {
+
+    log_android(ANDROID_LOG_ERROR,"in write tcp data with length: %d", length);
+
     if (write_tcp(args, cur, buffer, length, 0, 1, 0, 0) < 0) {
         cur->state = TCP_CLOSING;
         return -1;
@@ -1323,7 +1350,7 @@ ssize_t write_tcp(const struct arguments *args, const struct tcp_session *cur,
               dest, sizeof(dest));
 
     // Send packet
-    log_android(ANDROID_LOG_DEBUG,
+    log_android(ANDROID_LOG_ERROR,
                 "TCP sending%s%s%s%s to tun %s/%u seq %u ack %u data %u",
                 (tcp->syn ? " SYN" : ""),
                 (tcp->ack ? " ACK" : ""),