Я для этого уже давно написал и использую такой патчик:
			Code Select 
--- netxms-1.2.10/src/agent/subagents/linux/linux.cpp	2013-11-15 18:04:23.000000000 +0400
+++ netxms-1.2.10-r1/src/agent/subagents/linux/linux.cpp	2014-01-09 17:51:00.000000000 +0400
@@ -180,9 +180,9 @@
 	{ _T("Net.Interface.AdminStatus(*)"), H_NetIfInfoFromIOCTL, (TCHAR *)IF_INFO_ADMIN_STATUS,
 		DCI_DT_INT,		DCIDESC_NET_INTERFACE_ADMINSTATUS },
 	{ _T("Net.Interface.BytesIn(*)"),     H_NetIfInfoFromProc, (TCHAR *)IF_INFO_BYTES_IN,
-		DCI_DT_UINT,	DCIDESC_NET_INTERFACE_BYTESIN },
+		DCI_DT_UINT64,	DCIDESC_NET_INTERFACE_BYTESIN },
 	{ _T("Net.Interface.BytesOut(*)"),    H_NetIfInfoFromProc, (TCHAR *)IF_INFO_BYTES_OUT,
-		DCI_DT_UINT,	DCIDESC_NET_INTERFACE_BYTESOUT },
+		DCI_DT_UINT64,	DCIDESC_NET_INTERFACE_BYTESOUT },
 	{ _T("Net.Interface.Description(*)"), H_NetIfInfoFromIOCTL, (TCHAR *)IF_INFO_DESCRIPTION,
 		DCI_DT_STRING,	DCIDESC_NET_INTERFACE_DESCRIPTION },
 	{ _T("Net.Interface.InErrors(*)"),    H_NetIfInfoFromProc, (TCHAR *)IF_INFO_IN_ERRORS,
diff -ur netxms-1.2.10/src/agent/subagents/linux/net.cpp netxms-1.2.10-r1/src/agent/subagents/linux/net.cpp
--- netxms-1.2.10/src/agent/subagents/linux/net.cpp	2013-11-29 17:56:24.000000000 +0400
+++ netxms-1.2.10-r1/src/agent/subagents/linux/net.cpp	2014-01-09 17:53:39.000000000 +0400
@@ -526,15 +526,15 @@
    int i;
    char *eptr, szBuffer[256];
    const char *pszWord;
-   DWORD dwValue;
+   QWORD qwValue;
    LONG nRet = SYSINFO_RC_ERROR;
    for(i = 0, pszWord = pszLine; i <= nPos; i++)
       pszWord = ExtractWordA(pszWord, szBuffer);
-   dwValue = strtoul(szBuffer, &eptr, 0);
+   qwValue = (QWORD) strtoull(szBuffer, &eptr, 0);
    if (*eptr == 0)
    {
-      ret_uint(pValue, dwValue);
+      ret_uint64(pValue, qwValue);
       nRet = SYSINFO_RC_SUCCESS;
    }
    return nRet;
