internal or external IP

What would be an easy way to determine if the source IP in some IIS logs on an exchange cas server is that of an internal ip address ie desktop computer of user connected to our private network or an external ip ie personal smartphone or pc when remotely accessing their mail via active sync on their own phone outlook anywhere or owa etc
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K BCommented:
External IP addresses can be searched to determine who owns it.

Search top right "who is"

If the source IP address is that of your internal network range - it is originating from the inside.
If you use RDS or citrix it would be those "access" logs.

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and if you search for a private/internal address at,  arin will show you that it's "private" (Name      PRIVATE-ADDRESS-BBLK-RFC1918-IANA-RESERVED"

So either way, search at and it'll tell you.
Gerwin Jansen, EE MVETopic Advisor Commented:
Filter out all addresses from the internal IP range(s), what remains is the list you want.

Your IIS log files are on the windows platform so you can use 'findstr' on a command line to filter, like this:

findstr /i /v "<ip pattern>" *.log

For example:

findstr /i /v "10.0.1" *.log
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