A wellhead is provided. In one embodiment, the wellhead includes a plug for sealing a side passage of the wellhead. The plug may include an outer member, an inner member extending through the outer member and coupled to the outer member with at least one degree of freedom of movement relative to the outer member, and a moveable seal disposed around the outer member. In some embodiments, the moveable seal is configured to seal against the side passage in response to being moved on the outer member by the inner member.