diff --git a/Makefile b/Makefile
index e470246..aa625c6 100644
--- a/Makefile
+++ b/Makefile
@@ -29,8 +29,8 @@ CFLAGS ?=-Wall -DLIBPCRE -g $(CFLAGS_COV)
 LIBS=-lm -lpcre2-8
 OBJS=sslh-conf.o common.o log.o sslh-main.o probe.o tls.o argtable3.o collection.o gap.o
 FORK_OBJS=$(OBJS) sslh-fork.o 
-SELECT_OBJS=$(OBJS) processes.o udp-listener.o sslh-select.o 
-EV_OBJS=$(OBJS) processes.o udp-listener.o sslh-ev.o 
+SELECT_OBJS=$(OBJS) processes.o udp-listener.o sslh-select.o hash.o
+EV_OBJS=$(OBJS) processes.o udp-listener.o sslh-ev.o hash.o
 
 CONDITIONAL_TARGETS=
 
diff --git a/hashtest/htest b/hashtest/htest
index 55dc1c8..b525ec4 100755
Binary files a/hashtest/htest and b/hashtest/htest differ
diff --git a/processes.h b/processes.h
index a15d400..541d133 100644
--- a/processes.h
+++ b/processes.h
@@ -16,6 +16,8 @@ struct loop_info {
                           * select() */
     gap_array* probing_list;  /* Pointers to cnx that are in probing mode */
 
+    hash* hash_sources; /* UDP remote sources previously encountered */
+
     watchers* watchers;
 
     cnx_collection* collection; /* Collection of connections linked to this loop */
diff --git a/sslh-ev.c b/sslh-ev.c
index 8410730..ff6f365 100644
--- a/sslh-ev.c
+++ b/sslh-ev.c
@@ -25,6 +25,7 @@
 #include "processes.h"
 #include "gap.h"
 #include "log.h"
+#include "udp-listener.h"
 
 
 const char* server_type = "sslh-ev";
@@ -147,6 +148,8 @@ void main_loop(struct listen_endpoint listen_sockets[], int num_addr_listen)
 
     ev_info.collection = collection_init(0);
     ev_info.probing_list = gap_init(0);
+    udp_init(&ev_info);
+
     watchers_init(&ev_info.watchers, listen_sockets, num_addr_listen);
     ev_set_userdata(EV_A_ &ev_info);
 
diff --git a/sslh-select.c b/sslh-select.c
index c65847f..f15365b 100644
--- a/sslh-select.c
+++ b/sslh-select.c
@@ -135,6 +135,7 @@ void main_loop(struct listen_endpoint listen_sockets[], int num_addr_listen)
 
     fd_info.num_probing = 0; 
     fd_info.probing_list = gap_init(0);
+    udp_init(&fd_info);
 
     watchers_init(&fd_info.watchers, listen_sockets, num_addr_listen);
 
diff --git a/t_load b/t_load
index 8131605..2fc6a5f 100755
--- a/t_load
+++ b/t_load
@@ -20,7 +20,7 @@ use Conf::Libconfig;
 
 # How many total clients to we start? Each client will pick
 # a new protocol among what's in test.cfg.
-my $NUM_CNX = 50;
+my $NUM_CNX = 16;
 
 # Delay between starting new processes when starting up. If
 # you start 200 processes in under a second, things go wrong
@@ -35,7 +35,7 @@ my $block_rpt = 5;
 # Probability to stop a client after a message (e.g. with
 # .01 a client will send an average of 100 messages before
 # disconnecting).
-my $stop_client_probability = .001;
+my $stop_client_probability = .0001;
 
 ##END CONFIG
 
@@ -65,21 +65,21 @@ my %connect_params = (
         test_data => "foo bar",
         resp_len => 12,
     },
-        ssh => {
-        sleep => 20,  # So it times out 50% of connections
-        test_data => "SSH-2.0 hello",
-        resp_len => 18,  # length "ssh: SSH-2.0 hello" => 18
-    },
-    tinc => {
-        sleep => 0,
-        test_data => "0 ",
-        resp_len => 8, # length "tinc: 0 " => 10 
-    },
-    openvpn => {
-        sleep => 0,
-        test_data => "\x00\x00",
-        resp_len => 11,  # length "openvpn: \x0\x0" => 11
-    },
+    #        ssh => {
+    #        sleep => 20,  # So it times out 50% of connections
+    #        test_data => "SSH-2.0 hello",
+    #        resp_len => 18,  # length "ssh: SSH-2.0 hello" => 18
+    #    },
+    #    tinc => {
+    #        sleep => 0,
+    #        test_data => "0 ",
+    #        resp_len => 8, # length "tinc: 0 " => 10 
+    #    },
+    #    openvpn => {
+    #        sleep => 0,
+    #        test_data => "\x00\x00",
+    #        resp_len => 11,  # length "openvpn: \x0\x0" => 11
+    #    },
 );
 
 sub connect_service {
diff --git a/udp-listener.c b/udp-listener.c
index ea5d4f4..2b065f7 100644
--- a/udp-listener.c
+++ b/udp-listener.c
@@ -27,6 +27,9 @@
 #include "sslh-conf.h"
 #include "udp-listener.h"
 
+typedef struct connection* hash_item;
+#include "hash.h"
+
 
 /* returns date at which this socket times out. */
 static int udp_timeout(struct connection* cnx)
@@ -36,6 +39,89 @@ static int udp_timeout(struct connection* cnx)
     return cnx->proto->udp_timeout + cnx->last_active;
 }
 
+/* Incoming connections are of course all received on a single socket. Create a
+ * hash that associates (incoming sockaddr) => struct connection*, so finding
+ * the connection related to an incoming packet is fast.
+ */
+
+
+
+static int cnx_cmp(struct connection* cnx1, struct connection* cnx2)
+{
+    struct sockaddr* addr1 = &cnx1->client_addr;
+    socklen_t addrlen1 = cnx1->addrlen;
+
+    struct sockaddr* addr2 = &cnx2->client_addr;
+    socklen_t addrlen2 = cnx2->addrlen;
+
+    if (addrlen1 != addrlen2) return -1;
+
+    return memcmp(addr1, addr2, addrlen1);
+}
+
+/* From an IP address, create something that's useable as a hash key.
+ * Currently:
+ * lowest bytes of remote port */
+static int hash_make_key(hash_item new)
+{
+    struct sockaddr* addr = &new->client_addr;
+    //socklen_t addrlen = new->addrlen;
+    struct sockaddr_in* addr4;
+    struct sockaddr_in6* addr6;
+    int out;
+
+    switch (addr->sa_family) {
+    case AF_INET:
+        addr4 = (struct sockaddr_in*)addr;
+        out = addr4->sin_port;
+        break;
+
+    case AF_INET6:
+        addr6 = (struct sockaddr_in6*)addr;
+        out = addr6->sin6_port;
+        break;
+
+    default: /* Just use the first bytes, skipping the address family */
+        out = ((char*)addr)[2];
+        break;
+    }
+    return out;
+}
+
+/* Init the UDP subsystem.
+ * - Initialise the hash
+ * - that's all, folks
+ * */
+void udp_init(struct loop_info* fd_info)
+{
+    fd_info->hash_sources = hash_init(&hash_make_key, &cnx_cmp);
+}
+
+
+/* Find if the specified source has been seen before.
+ * If yes, returns file descriptor of connection
+ * If not, returns -1
+ * */
+static int known_source(hash* h, struct sockaddr* addr, socklen_t addrlen)
+{
+    struct connection search;
+    search.client_addr = *addr;
+    search.addrlen = addrlen;
+
+    struct connection* cnx = hash_find(h, &search);
+    if (!cnx) return -1;
+    return cnx->q[0].fd;
+}
+
+
+
+static int new_source(hash* h, struct connection* new)
+{
+    return hash_insert(h, new);
+}
+
+
+
 /* Check all connections to see if a UDP connections has timed out, then free
  * it. At the same time, keep track of the closest, next timeout. Only do the
  * search through connections if that timeout actually happened. If the
@@ -71,6 +157,7 @@ void udp_timeouts(struct loop_info* fd_info)
                 watchers_del_read(fd_info->watchers, i);
                 watchers_del_write(fd_info->watchers, i);
                 collection_remove_cnx(fd_info->collection, cnx);
+                hash_remove(fd_info->hash_sources, cnx);
             } else {
                 if (timeout < next_timeout) next_timeout = timeout;
             }
@@ -81,27 +168,6 @@ void udp_timeouts(struct loop_info* fd_info)
         fd_info->next_timeout = next_timeout;
 }
 
-/* Find if the specified source has been seen before. -1 if not found
- *
- * TODO This is linear search and needs to be changed to something better for
- * production if we have more than a dozen sources
- * Also, this assumes src_addr from recvfrom() are repeatable for a specific
- * source...
- * */
-static int known_source(cnx_collection* collection, int max_fd, struct sockaddr* addr, socklen_t addrlen)
-{
-    int i;
-
-    for (i = 0; i < max_fd; i++) {
-        struct connection* cnx = collection_get_cnx_from_fd(collection, i);
-        if (cnx && (cnx->type == SOCK_DGRAM) && cnx->target_sock) {
-            if (!memcmp(&cnx->client_addr, addr, addrlen)) {
-                return i;
-            }
-        }
-    }
-    return -1;
-}
 
 /* Process UDP coming from outside (client towards server)
  * If it's a new source, probe; otherwise, forward to previous target 
@@ -124,6 +190,7 @@ int udp_c2s_forward(int sockfd, struct loop_info* fd_info)
                          This will do.  Dynamic allocation is possible with the MSG_PEEK flag in recvfrom(2), but that'd imply
                          malloc/free overhead for each packet, when really 64K is not that much */
 
+
     udp_timeouts(fd_info);
 
     addrlen = sizeof(src_addr);
@@ -132,7 +199,7 @@ int udp_c2s_forward(int sockfd, struct loop_info* fd_info)
         perror("recvfrom");
         return -1;
     }
-    target = known_source(collection, max_fd, &src_addr, addrlen);
+    target = known_source(fd_info->hash_sources, &src_addr, addrlen);
     addrinfo.ai_addr = &src_addr;
     addrinfo.ai_addrlen = addrlen;
     print_message(msg_probe_info, "received %ld UDP from %d:%s\n", 
@@ -160,6 +227,13 @@ int udp_c2s_forward(int sockfd, struct loop_info* fd_info)
         cnx->client_addr = src_addr;
         cnx->addrlen = addrlen;
         cnx->local_endpoint = sockfd;
+
+        res = new_source(fd_info->hash_sources, cnx);
+        if (res == -1) {
+            print_message(msg_connections_error, "Out of hash space for new incoming UDP connection");
+            collection_remove_cnx(collection, cnx);
+            return -1;
+        }
     }
     cnx = collection_get_cnx_from_fd(collection, target);
 
@@ -169,6 +243,7 @@ int udp_c2s_forward(int sockfd, struct loop_info* fd_info)
     cnx->last_active = time(NULL);
     print_message(msg_fd, "sending %d to %s\n", 
             res, sprintaddr(data, sizeof(data), cnx->proto->saddr));
+
     return out;
 }
 
diff --git a/udp-listener.h b/udp-listener.h
index 23a62dc..67c2a00 100644
--- a/udp-listener.h
+++ b/udp-listener.h
@@ -21,4 +21,7 @@ int udp_c2s_forward(int sockfd, struct loop_info* fd_info);
 /* Process UDP coming from inside (server towards client) */
 void udp_s2c_forward(struct connection* cnx);
 
+
+void udp_init(struct loop_info* fd_info);
+
 #endif /* UDPLISTENER_H */