steamnetworkingsockets_messages_udp.proto

Protobufs / steamnetworkingsockets_messages_udp.proto

CS2 build 25218825 · Steam date 2026-09-09 · platform windows-x86_64 · schema format 2.2

Group: GC and Steam SDKMessages: 7 top-level, 7 totalEnums: 1 top-level, 2 total

Imports: steamnetworkingsockets_messages_certs.proto, steamnetworkingsockets_messages.proto

Enums

ESteamNetworkingUDPMsgID

Steam Networking UDP Msg ID SteamNetworking NetworkingUDP UDPMsg MsgID k_ESteamNetworkingUDPMsg_ChallengeRequest k_ESteamNetworkingUDPMsg_ChallengeReply k_ESteamNetworkingUDPMsg_ConnectRequest k_ESteamNetworkingUDPMsg_ConnectOK k_ESteamNetworkingUDPMsg_ConnectionClosed k_ESteamNetworkingUDPMsg_NoConnection

Name	Number	Message
k_ESteamNetworkingUDPMsg_ChallengeRequest	32
k_ESteamNetworkingUDPMsg_ChallengeReply	33
k_ESteamNetworkingUDPMsg_ConnectRequest	34
k_ESteamNetworkingUDPMsg_ConnectOK	35
k_ESteamNetworkingUDPMsg_ConnectionClosed	36
k_ESteamNetworkingUDPMsg_NoConnection	37

Messages

CMsgSteamSockets_UDP_ChallengeRequest

CMsgSteamSockets Msg Steam Sockets MsgSteam SteamSockets UDP ChallengeRequest Challenge Request connection_id my_timestamp protocol_version

Field	Number	Label	Type	Default	Description
connection_id	1	optional	fixed32
my_timestamp	3	optional	fixed64
protocol_version	4	optional	uint32

CMsgSteamSockets_UDP_ChallengeReply

CMsgSteamSockets Msg Steam Sockets MsgSteam SteamSockets UDP ChallengeReply Challenge Reply connection_id challenge your_timestamp protocol_version

Field	Number	Label	Type	Default	Description
connection_id	1	optional	fixed32
challenge	2	optional	fixed64
your_timestamp	3	optional	fixed64
protocol_version	4	optional	uint32

CMsgSteamSockets_UDP_ConnectRequest

CMsgSteamSockets Msg Steam Sockets MsgSteam SteamSockets UDP ConnectRequest Connect Request client_connection_id challenge legacy_client_steam_id cert my_timestamp ping_est_ms crypt legacy_protocol_version legacy_identity_binary identity_string

Field	Number	Label	Type	Default	Description
client_connection_id	1	optional	fixed32
challenge	2	optional	fixed64
legacy_client_steam_id	3	optional	fixed64
cert	4	optional	CMsgSteamDatagramCertificateSigned
my_timestamp	5	optional	fixed64
ping_est_ms	6	optional	uint32
crypt	7	optional	CMsgSteamDatagramSessionCryptInfoSigned
legacy_protocol_version	8	optional	uint32
legacy_identity_binary	9	optional	CMsgSteamNetworkingIdentityLegacyBinary
identity_string	10	optional	string

CMsgSteamSockets_UDP_ConnectOK

CMsgSteamSockets Msg Steam Sockets MsgSteam SteamSockets UDP ConnectOK Connect OK client_connection_id legacy_server_steam_id your_timestamp delay_time_usec server_connection_id crypt cert legacy_identity_binary identity_string

Field	Number	Label	Type	Default	Description
client_connection_id	1	optional	fixed32
legacy_server_steam_id	2	optional	fixed64
your_timestamp	3	optional	fixed64
delay_time_usec	4	optional	uint32
server_connection_id	5	optional	fixed32
crypt	7	optional	CMsgSteamDatagramSessionCryptInfoSigned
cert	8	optional	CMsgSteamDatagramCertificateSigned
legacy_identity_binary	10	optional	CMsgSteamNetworkingIdentityLegacyBinary
identity_string	11	optional	string

CMsgSteamSockets_UDP_ConnectionClosed

CMsgSteamSockets Msg Steam Sockets MsgSteam SteamSockets UDP ConnectionClosed Connection Closed debug reason_code to_connection_id from_connection_id

Field	Number	Label	Type	Default	Description
debug	2	optional	string
reason_code	3	optional	uint32
to_connection_id	4	optional	fixed32
from_connection_id	5	optional	fixed32

CMsgSteamSockets_UDP_NoConnection

CMsgSteamSockets Msg Steam Sockets MsgSteam SteamSockets UDP NoConnection No Connection from_connection_id to_connection_id

Field	Number	Label	Type	Default	Description
from_connection_id	2	optional	fixed32
to_connection_id	3	optional	fixed32

CMsgSteamSockets_UDP_Stats

CMsgSteamSockets Msg Steam Sockets MsgSteam SteamSockets UDP Stats stats flags

Field	Number	Label	Type	Default	Description
stats	1	optional	CMsgSteamDatagramConnectionQuality
flags	3	optional	uint32

CMsgSteamSockets_UDP_Stats.Flags

ACK_REQUEST_E2E ACK_REQUEST_IMMEDIATE NOT_PRIMARY_TRANSPORT_E2E

Name	Number	Message
ACK_REQUEST_E2E	2
ACK_REQUEST_IMMEDIATE	4
NOT_PRIMARY_TRANSPORT_E2E	16

Reference graph

Message reference graph (7 edges)

flowchart LR
    n0["CMsgSteamSockets_UDP_ConnectRequest"]
    n1["CMsgSteamDatagramCertificateSigned"]
    n0 --> n1
    n2["CMsgSteamDatagramSessionCryptInfoSigned"]
    n0 --> n2
    n3["CMsgSteamNetworkingIdentityLegacyBinary"]
    n0 --> n3
    n4["CMsgSteamSockets_UDP_ConnectOK"]
    n4 --> n2
    n4 --> n1
    n4 --> n3
    n5["CMsgSteamSockets_UDP_Stats"]
    n6["CMsgSteamDatagramConnectionQuality"]
    n5 --> n6