It seems that many people have problems backing up an ISA server using Symantec (formerly Veritas) Backup Exec.

Here's what worked for me:

• To get ISA able to be browsed and backed up, you need to add some rules to ISA to allow BE to access it, and to allow it to be browsed from the network.
• Create a new protocol in ISA (I called mine  BackupExec). Set the Primary Connections to be TCP ports 10000-10025 Outbound.
• Create a rule to allow your newly-created BackupExec protocol from your BE server to your ISA server.
• In BE, go to Tools, Options, Network and Firewall, and select Enable remote agent TCP dynamic port range: 10000 - 10025.
• On your ISA server you may have to enable the Firewall Client Install option in System Policy Editor. (Action menu, Edit Syatem Policy, Firewall Client Installation)

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