Problem - Kevin Tafuro

ReferencedDomainName = (LPTSTR)LocalAlloc(LMEM_FIXED, cbReferencedDomainName);
if (!ReferencedDomainName) {
LocalFree(lpszName);
return 0;
}
if (!LookupAccountSid(lpszSystemName, Sid, lpszName, &cbName,
ReferencedDomainName, &cbReferencedDomainName, &eUse)) {
LocalFree(ReferencedDomainName);
LocalFree(lpszName);
return 0;
}
LocalFree(ReferencedDomainName);
return lpszName;
}
8.4 Restricting Access Based on Hostname or IP
Address
Problem
You want to restrict access to the network based on hostname or IP address.
Solution
First, get the IP address of the remote connection, and verify that the address has a
hostname associated with it. To ensure that the hostname is not being spoofed (i.e.,
the address reverses to one hostname, but the hostname does not map to that IP
address), look up the hostname and compare the resulting IP address with the IP
address of the connection; if the IP addresses do not match, the hostname is likely
being spoofed.
Next, compare the IP address and/or hostname with a set of rules that determine
whether to grant the remote connection access.
Discussion
Restricting access based on the remote connection’s IP address or
hostname is risky at best. The hostname and/or IP address could be
spoofed, or the remote system could be compromised with an attacker
in control. Address-based access control is no substitute for strong
authentication methods.
Restricting Access Based on Hostname or IP Address | 379
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