They're not sipp-esp and sipp-ah, just esp and ah

src/etc/protocols

@@ -1,7 +1,7 @@
 #
 # Internet (IP) protocols
 #
-#	$OpenBSD: protocols,v 1.7 1998/05/13 21:12:35 deraadt Exp $
+#	$OpenBSD: protocols,v 1.8 1998/08/01 05:34:51 angelos Exp $
 #
 # Updated based on RFC 1340, Assigned Numbers (July 1992).
 # See also http://www.iana.org/in-notes/iana/assignments/protocol-numbers
@@ -56,8 +56,8 @@ rsvp	46	RSVP		# Reservation Protocol
 gre	47	GRE		# General Routing Encapsulation
 mhrp	48	MHRP		# Mobile Host Routing Protocol
 bna	49	BNA		# BNA
-sipp-esp 50	SIPP-ESP	# SIPP Encap Security Payload
-sipp-ah	51	SIPP-AH		# SIPP Authentication Header
+esp 	50	IPSEC-ESP	# Encap Security Payload
+ah	51	IPSEC-AH	# Authentication Header
 i-nlsp	52	I-NLSP		# Integrated Net Layer Security TUBA
 swipe	53	SWIPE		# IP with Encryption
 nhrp	54	NHRP		# NBMA Next Hop Resolution Protocol