diff --git a/icmp.c b/icmp.c
index 676fa64..a4b6a47 100644
--- a/icmp.c
+++ b/icmp.c
@@ -79,7 +79,7 @@ void icmp_sock_handler(const struct ctx *c, union epoll_ref ref,
 	(void)events;
 	(void)now;
 
-	n = recvfrom(ref.s, buf, sizeof(buf), 0, (struct sockaddr *)&sr, &sl);
+	n = recvfrom(ref.fd, buf, sizeof(buf), 0, (struct sockaddr *)&sr, &sl);
 	if (n < 0)
 		return;
 
@@ -182,7 +182,7 @@ int icmp_tap_handler(const struct ctx *c, int af, const void *addr,
 				    bind_if, id, iref.u32);
 			if (s < 0)
 				goto fail_sock;
-			if (s > SOCKET_MAX) {
+			if (s > FD_REF_MAX) {
 				close(s);
 				return 1;
 			}
@@ -236,7 +236,7 @@ int icmp_tap_handler(const struct ctx *c, int af, const void *addr,
 				    bind_if, id, iref.u32);
 			if (s < 0)
 				goto fail_sock;
-			if (s > SOCKET_MAX) {
+			if (s > FD_REF_MAX) {
 				close(s);
 				return 1;
 			}
diff --git a/passt.c b/passt.c
index 9123868..ae69478 100644
--- a/passt.c
+++ b/passt.c
@@ -55,12 +55,11 @@
 
 char pkt_buf[PKT_BUF_BYTES]	__attribute__ ((aligned(PAGE_SIZE)));
 
-char *ip_proto_str[IPPROTO_SCTP + 1] = {
-	[IPPROTO_ICMP]		= "ICMP",
-	[IPPROTO_TCP]		= "TCP",
-	[IPPROTO_UDP]		= "UDP",
-	[IPPROTO_ICMPV6]	= "ICMPV6",
-	[IPPROTO_SCTP]		= "SCTP",
+char *epoll_type_str[EPOLL_TYPE_MAX + 1] = {
+	[EPOLL_TYPE_TCP]	= "TCP socket",
+	[EPOLL_TYPE_UDP]	= "UDP socket",
+	[EPOLL_TYPE_ICMP]	= "ICMP socket",
+	[EPOLL_TYPE_ICMPV6]	= "ICMPv6 socket",
 };
 
 /**
@@ -73,16 +72,16 @@ char *ip_proto_str[IPPROTO_SCTP + 1] = {
 static void sock_handler(struct ctx *c, union epoll_ref ref,
 			 uint32_t events, const struct timespec *now)
 {
-	trace("%s: %s packet from socket %i (events: 0x%08x)",
+	trace("%s: packet from %s %i (events: 0x%08x)",
 	      c->mode == MODE_PASST ? "passt" : "pasta",
-	      IP_PROTO_STR(ref.proto), ref.s, events);
+	      EPOLL_TYPE_STR(ref.type), ref.fd, events);
 
-	if (!c->no_tcp && ref.proto == IPPROTO_TCP)
-		tcp_sock_handler( c, ref, events, now);
-	else if (!c->no_udp && ref.proto == IPPROTO_UDP)
-		udp_sock_handler( c, ref, events, now);
+	if (!c->no_tcp && ref.type == EPOLL_TYPE_TCP)
+		tcp_sock_handler(c, ref, events, now);
+	else if (!c->no_udp && ref.type == EPOLL_TYPE_UDP)
+		udp_sock_handler(c, ref, events, now);
 	else if (!c->no_icmp &&
-		 (ref.proto == IPPROTO_ICMP || ref.proto == IPPROTO_ICMPV6))
+		 (ref.type == EPOLL_TYPE_ICMP || ref.type == EPOLL_TYPE_ICMPV6))
 		icmp_sock_handler(c, ref, events, now);
 }
 
diff --git a/passt.h b/passt.h
index edc4841..2110781 100644
--- a/passt.h
+++ b/passt.h
@@ -42,9 +42,27 @@ union epoll_ref;
 #include "udp.h"
 
 /**
- * union epoll_ref - Breakdown of reference for epoll socket bookkeeping
- * @proto:	IP protocol number
- * @s:		Socket number (implies 2^24-1 limit on number of descriptors)
+ * enum epoll_type - Different types of fds we poll over
+ */
+enum epoll_type {
+	/* Special value to indicate an invalid type */
+	EPOLL_TYPE_NONE = 0,
+	/* Sockets and timerfds for TCP handling */
+	EPOLL_TYPE_TCP,
+	/* UDP sockets */
+	EPOLL_TYPE_UDP,
+	/* IPv4 ICMP sockets */
+	EPOLL_TYPE_ICMP,
+	/* ICMPv6 sockets */
+	EPOLL_TYPE_ICMPV6,
+
+	EPOLL_TYPE_MAX = EPOLL_TYPE_ICMPV6,
+};
+
+/**
+ * union epoll_ref - Breakdown of reference for epoll fd bookkeeping
+ * @type:	Type of fd (tells us what to do with events)
+ * @fd:		File descriptor number (implies < 2^24 total descriptors)
  * @tcp:	TCP-specific reference part
  * @udp:	UDP-specific reference part
  * @icmp:	ICMP-specific reference part
@@ -53,10 +71,10 @@ union epoll_ref;
  */
 union epoll_ref {
 	struct {
-		int32_t		proto:8,
-#define SOCKET_REF_BITS		24
-#define SOCKET_MAX		MAX_FROM_BITS(SOCKET_REF_BITS)
-				s:SOCKET_REF_BITS;
+		enum epoll_type type:8;
+#define FD_REF_BITS		24
+#define FD_REF_MAX		MAX_FROM_BITS(FD_REF_BITS)
+		int32_t		fd:FD_REF_BITS;
 		union {
 			union tcp_epoll_ref tcp;
 			union udp_epoll_ref udp;
@@ -78,10 +96,10 @@ static_assert(sizeof(union epoll_ref) <= sizeof(union epoll_data),
 #define PKT_BUF_BYTES		MAX(TAP_BUF_BYTES, 0)
 extern char pkt_buf		[PKT_BUF_BYTES];
 
-extern char *ip_proto_str[];
-#define IP_PROTO_STR(n)							\
-	(((uint8_t)(n) <= IPPROTO_SCTP && ip_proto_str[(n)]) ?		\
-			  ip_proto_str[(n)] : "?")
+extern char *epoll_type_str[];
+#define EPOLL_TYPE_STR(n)						\
+	(((uint8_t)(n) <= EPOLL_TYPE_MAX && epoll_type_str[(n)]) ?	\
+	                                    epoll_type_str[(n)] : "?")
 
 #include <resolv.h>	/* For MAXNS below */
 
diff --git a/tcp.c b/tcp.c
index d9ecee5..18b781a 100644
--- a/tcp.c
+++ b/tcp.c
@@ -643,7 +643,7 @@ static void conn_flag_do(const struct ctx *c, struct tcp_tap_conn *conn,
 static int tcp_epoll_ctl(const struct ctx *c, struct tcp_tap_conn *conn)
 {
 	int m = conn->c.in_epoll ? EPOLL_CTL_MOD : EPOLL_CTL_ADD;
-	union epoll_ref ref = { .proto = IPPROTO_TCP, .s = conn->sock,
+	union epoll_ref ref = { .type = EPOLL_TYPE_TCP, .fd = conn->sock,
 				.tcp.index = CONN_IDX(conn) };
 	struct epoll_event ev = { .data.u64 = ref.u64 };
 
@@ -663,8 +663,8 @@ static int tcp_epoll_ctl(const struct ctx *c, struct tcp_tap_conn *conn)
 	conn->c.in_epoll = true;
 
 	if (conn->timer != -1) {
-		union epoll_ref ref_t = { .proto = IPPROTO_TCP,
-					  .s = conn->sock,
+		union epoll_ref ref_t = { .type = EPOLL_TYPE_TCP,
+					  .fd = conn->sock,
 					  .tcp.timer = 1,
 					  .tcp.index = CONN_IDX(conn) };
 		struct epoll_event ev_t = { .data.u64 = ref_t.u64,
@@ -692,8 +692,8 @@ static void tcp_timer_ctl(const struct ctx *c, struct tcp_tap_conn *conn)
 		return;
 
 	if (conn->timer == -1) {
-		union epoll_ref ref = { .proto = IPPROTO_TCP,
-					.s = conn->sock,
+		union epoll_ref ref = { .type = EPOLL_TYPE_TCP,
+					.fd = conn->sock,
 					.tcp.timer = 1,
 					.tcp.index = CONN_IDX(conn) };
 		struct epoll_event ev = { .data.u64 = ref.u64,
@@ -701,7 +701,7 @@ static void tcp_timer_ctl(const struct ctx *c, struct tcp_tap_conn *conn)
 		int fd;
 
 		fd = timerfd_create(CLOCK_MONOTONIC, 0);
-		if (fd == -1 || fd > SOCKET_MAX) {
+		if (fd == -1 || fd > FD_REF_MAX) {
 			debug("TCP: failed to get timer: %s", strerror(errno));
 			if (fd > -1)
 				close(fd);
@@ -1908,7 +1908,7 @@ int tcp_conn_new_sock(const struct ctx *c, sa_family_t af)
 
 	s = socket(af, SOCK_STREAM | SOCK_NONBLOCK, IPPROTO_TCP);
 
-	if (s > SOCKET_MAX) {
+	if (s > FD_REF_MAX) {
 		close(s);
 		return -EIO;
 	}
@@ -2791,7 +2791,7 @@ static void tcp_conn_from_sock(struct ctx *c, union epoll_ref ref,
 	 * https://github.com/llvm/llvm-project/issues/58992
 	 */
 	memset(&sa, 0, sizeof(struct sockaddr_in6));
-	s = accept4(ref.s, (struct sockaddr *)&sa, &sl, SOCK_NONBLOCK);
+	s = accept4(ref.fd, (struct sockaddr *)&sa, &sl, SOCK_NONBLOCK);
 	if (s < 0)
 		return;
 
@@ -2948,7 +2948,7 @@ void tcp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
 	conn = tc + ref.tcp.index;
 
 	if (conn->c.spliced)
-		tcp_splice_sock_handler(c, &conn->splice, ref.s, events);
+		tcp_splice_sock_handler(c, &conn->splice, ref.fd, events);
 	else
 		tcp_tap_sock_handler(c, &conn->tap, events);
 }
@@ -2999,7 +2999,7 @@ static int tcp_sock_init_af(const struct ctx *c, int af, in_port_t port,
 int tcp_sock_init(const struct ctx *c, sa_family_t af, const void *addr,
 		  const char *ifname, in_port_t port)
 {
-	int r4 = SOCKET_MAX + 1, r6 = SOCKET_MAX + 1;
+	int r4 = FD_REF_MAX + 1, r6 = FD_REF_MAX + 1;
 
 	if (af == AF_UNSPEC && c->ifi4 && c->ifi6)
 		/* Attempt to get a dual stack socket */
@@ -3013,7 +3013,7 @@ int tcp_sock_init(const struct ctx *c, sa_family_t af, const void *addr,
 	if ((af == AF_INET6 || af == AF_UNSPEC) && c->ifi6)
 		r6 = tcp_sock_init_af(c, AF_INET6, port, addr, ifname);
 
-	if (IN_INTERVAL(0, SOCKET_MAX, r4) || IN_INTERVAL(0, SOCKET_MAX, r6))
+	if (IN_INTERVAL(0, FD_REF_MAX, r4) || IN_INTERVAL(0, FD_REF_MAX, r6))
 		return 0;
 
 	return r4 < 0 ? r4 : r6;
diff --git a/tcp_conn.h b/tcp_conn.h
index 9e2b1bf..0b36940 100644
--- a/tcp_conn.h
+++ b/tcp_conn.h
@@ -62,7 +62,7 @@ struct tcp_tap_conn {
 	unsigned int	ws_to_tap	:TCP_WS_BITS;
 
 
-	int		sock		:SOCKET_REF_BITS;
+	int		sock		:FD_REF_BITS;
 
 	uint8_t		events;
 #define CLOSED			0
@@ -80,7 +80,7 @@ struct tcp_tap_conn {
 	(SOCK_ACCEPTED | TAP_SYN_RCVD | ESTABLISHED)
 
 
-	int		timer		:SOCKET_REF_BITS;
+	int		timer		:FD_REF_BITS;
 
 	uint8_t		flags;
 #define STALLED			BIT(0)
diff --git a/tcp_splice.c b/tcp_splice.c
index 03e14c1..24995e2 100644
--- a/tcp_splice.c
+++ b/tcp_splice.c
@@ -173,9 +173,9 @@ static int tcp_splice_epoll_ctl(const struct ctx *c,
 				struct tcp_splice_conn *conn)
 {
 	int m = conn->c.in_epoll ? EPOLL_CTL_MOD : EPOLL_CTL_ADD;
-	union epoll_ref ref_a = { .proto = IPPROTO_TCP, .s = conn->a,
+	union epoll_ref ref_a = { .type = EPOLL_TYPE_TCP, .fd = conn->a,
 				  .tcp.index = CONN_IDX(conn) };
-	union epoll_ref ref_b = { .proto = IPPROTO_TCP, .s = conn->b,
+	union epoll_ref ref_b = { .type = EPOLL_TYPE_TCP, .fd = conn->b,
 				  .tcp.index = CONN_IDX(conn) };
 	struct epoll_event ev_a = { .data.u64 = ref_a.u64 };
 	struct epoll_event ev_b = { .data.u64 = ref_b.u64 };
diff --git a/udp.c b/udp.c
index 5a852fb..62f8360 100644
--- a/udp.c
+++ b/udp.c
@@ -388,9 +388,9 @@ static void udp_sock6_iov_init(const struct ctx *c)
 int udp_splice_new(const struct ctx *c, int v6, in_port_t src, bool ns)
 {
 	struct epoll_event ev = { .events = EPOLLIN | EPOLLRDHUP | EPOLLHUP };
-	union epoll_ref ref = { .proto = IPPROTO_UDP,
+	union epoll_ref ref = { .type = EPOLL_TYPE_UDP,
 				.udp = { .splice = true, .ns = ns,
-					     .v6 = v6, .port = src }
+					 .v6 = v6, .port = src }
 			      };
 	struct udp_splice_port *sp;
 	int act, s;
@@ -406,7 +406,7 @@ int udp_splice_new(const struct ctx *c, int v6, in_port_t src, bool ns)
 	s = socket(v6 ? AF_INET6 : AF_INET, SOCK_DGRAM | SOCK_NONBLOCK,
 		   IPPROTO_UDP);
 
-	if (s > SOCKET_MAX) {
+	if (s > FD_REF_MAX) {
 		close(s);
 		return -EIO;
 	}
@@ -414,7 +414,7 @@ int udp_splice_new(const struct ctx *c, int v6, in_port_t src, bool ns)
 	if (s < 0)
 		return s;
 
-	ref.s = s;
+	ref.fd = s;
 
 	if (v6) {
 		struct sockaddr_in6 addr6 = {
@@ -767,7 +767,7 @@ void udp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
 		udp4_localname.sin_port = htons(dstport);
 	}
 
-	n = recvmmsg(ref.s, mmh_recv, n, 0, NULL);
+	n = recvmmsg(ref.fd, mmh_recv, n, 0, NULL);
 	if (n <= 0)
 		return;
 
@@ -980,7 +980,7 @@ int udp_sock_init(const struct ctx *c, int ns, sa_family_t af,
 		  const void *addr, const char *ifname, in_port_t port)
 {
 	union udp_epoll_ref uref = { .u32 = 0 };
-	int s, r4 = SOCKET_MAX + 1, r6 = SOCKET_MAX + 1;
+	int s, r4 = FD_REF_MAX + 1, r6 = FD_REF_MAX + 1;
 
 	if (ns) {
 		uref.port = (in_port_t)(port + c->udp.fwd_out.f.delta[port]);
@@ -1030,7 +1030,7 @@ int udp_sock_init(const struct ctx *c, int ns, sa_family_t af,
 		}
 	}
 
-	if (IN_INTERVAL(0, SOCKET_MAX, r4) || IN_INTERVAL(0, SOCKET_MAX, r6))
+	if (IN_INTERVAL(0, FD_REF_MAX, r4) || IN_INTERVAL(0, FD_REF_MAX, r6))
 		return 0;
 
 	return r4 < 0 ? r4 : r6;
diff --git a/util.c b/util.c
index 019c56c..2cac7ba 100644
--- a/util.c
+++ b/util.c
@@ -102,7 +102,7 @@ int sock_l4(const struct ctx *c, int af, uint8_t proto,
 	    const void *bind_addr, const char *ifname, uint16_t port,
 	    uint32_t data)
 {
-	union epoll_ref ref = { .proto = proto, .data = data };
+	union epoll_ref ref = { .data = data };
 	struct sockaddr_in addr4 = {
 		.sin_family = AF_INET,
 		.sin_port = htons(port),
@@ -118,9 +118,22 @@ int sock_l4(const struct ctx *c, int af, uint8_t proto,
 	int fd, sl, y = 1, ret;
 	struct epoll_event ev;
 
-	if (proto != IPPROTO_TCP && proto != IPPROTO_UDP &&
-	    proto != IPPROTO_ICMP && proto != IPPROTO_ICMPV6)
+	switch (proto) {
+	case IPPROTO_TCP:
+		ref.type = EPOLL_TYPE_TCP;
+		break;
+	case IPPROTO_UDP:
+		ref.type = EPOLL_TYPE_UDP;
+		break;
+	case IPPROTO_ICMP:
+		ref.type = EPOLL_TYPE_ICMP;
+		break;
+	case IPPROTO_ICMPV6:
+		ref.type = EPOLL_TYPE_ICMPV6;
+		break;
+	default:
 		return -EPFNOSUPPORT;	/* Not implemented. */
+	}
 
 	if (af == AF_UNSPEC) {
 		if (!DUAL_STACK_SOCKETS || bind_addr)
@@ -140,12 +153,12 @@ int sock_l4(const struct ctx *c, int af, uint8_t proto,
 		return ret;
 	}
 
-	if (fd > SOCKET_MAX) {
+	if (fd > FD_REF_MAX) {
 		close(fd);
 		return -EBADF;
 	}
 
-	ref.s = fd;
+	ref.fd = fd;
 
 	if (af == AF_INET) {
 		if (bind_addr)
@@ -188,8 +201,8 @@ int sock_l4(const struct ctx *c, int af, uint8_t proto,
 		if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE,
 			       ifname, strlen(ifname))) {
 			ret = -errno;
-			warn("Can't bind socket for %s port %u to %s, closing",
-			     ip_proto_str[proto], port, ifname);
+			warn("Can't bind %s socket for port %u to %s, closing",
+			     EPOLL_TYPE_STR(proto), port, ifname);
 			close(fd);
 			return ret;
 		}