l0:     ldh [12]              /* eth.type */
l1:     jeq #0x800, l2, l10   /* if ipv4, l3 */
l2:     ldb [23]              /* ip.proto */
l3:     jeq #0x11, l4, l10    /* if UDP, l5 */
l4:     ldh [20]              /* ip.frag_offset */
l5:     jset #0x1fff, l10, l6 /* if not fragmented, l7 */
l6:     ldxb 4*([14]&0xf)     /* ip.hdr_len * 4 -> X */
l7:     ldh [x + 16]          /* 36: UDP destination port */
l8:     jeq #0x44, l9, l10    /* if equal to 68, l10 */
l9:     ret #0x40000          /* keep 262144 bytes */
l10:    ret #0                /* discard the packet */