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It is possible to configure Win98/Me to increase the network security by enabling SMB signing, though enabling it will cause a performance hit because the security requires extra processing.

Configure client signing in Win98/Me:

[HKEY_LOCAL_MACHINE \System \CurrentControlSet \Services \VxD \VNetsup]
EnableSecuritySignature = 0 (Disabled = 0, Enabled = 1)
RequireSecuritySignature= 0 (Disabled = 0, Enabled = 1)

Note to enable SMB signing on Win95, then one have to install the Directory Services Client, which is found on the Win2k Srv. Install-Cd (X:\Clients\Win9x\Dsclient.exe) along with Winsock2 update and at least DUN 1.3+.
If doing domain logon check How the DSClient uses DNS lookup, and check that the DNS Server is properly configured or it can cause slow logon, as it has to timeout before it uses Netbios.

Related Description of SMB signing

More Info MS KB Q230545
More Info MS KB Q249841
More Info MS KB Q288358 (Download original DsClient.exe)
More Info MS KB Q283261 (Flaw in DsClient.exe)
More Info MS KB Q323455 (Description of hotfix for DsClient.exe) (Replaces Q323466)
More Info MS KB 555038 (Using DsClient.exe)