Modifying a flow table for a network accelerator can include, in response to determining that a flow table of a network accelerator does not include any rules corresponding to first packet data of a first flow received from a network, forwarding the first packet data to a host computer. Subsequent to the flow table being updated to include a new rule for the first flow, for second packet data of the first flow received from the network, the second packet data can be processed using the new rule. The second packet data can be queued. In response to receiving the first packet data from the host computer, the first packet data can be processed using the new rule. The processed packet data can be forwarded to a destination port followed by the queued second packet data.