startswith
if (startswith(arg, "authproto=")) {
} else if (startswith(arg, "myauthproto=")) {
} else if (startswith(arg, "myauthname=")) {
} else if (startswith(arg, "myauthsecret=") || startswith(arg, "myauthkey=")) {
} else if (startswith(arg, "hisauthproto=")) {
} else if (startswith(arg, "hisauthname=")) {
} else if (startswith(arg, "hisauthsecret=") || startswith(arg, "hisauthkey=")) {
} else if (startswith(arg, "max-noreceive=")) {
} else if (startswith(arg, "max-alive-missed=")) {
} else if (startswith(arg, "alive-interval=")) {
else if (startswith(arg, "lcp-timeout=")) {
} else if (startswith(arg, "idle-timeout=")) {
} else if (startswith(arg, "max-auth-failure=")) {
} else if (startswith(arg, "query-dns=")) {