Forum Discussion
How to Blocking ULtrasurf?
Hi All,
Is there any irule or configuration on F5 for blocking ultrasurf? I try to use ip intelegence irule on LTM,it did not work because the destination ip address is not registered as bad reputation ip address. I have checked the ip using iprep_lookup or on brigcloud webroot web.
I have also write irule to block on traffic client ssl hello traffic, but i dont know why ultrasurf is still work. Below is the irule
when CLIENT_ACCEPTED {
is there any idea?
Thanks n Regads
- petruk
20 Replies
- BT_90520
Nimbostratus
if the port is no longer 443, which is quite unlikely but I have small suspicion on StartTLS else it is not doing standard SSL if there is no Hello as expected. Cant we assume them to negotiate SSL with F5 instead to break their direct SSL with the proxy server (option in Ultrasurf config?). Else block them in their DNS request to known Ultrasurf DNS server ... Remove the Ultrasurf cache files in user temp directories, if there is automated way to always do discovery req that can be blocked - Petruk_Cemeng_7
Nimbostratus
yes, i think ultrasurf use stange ssl, still dont know how to block it. - BT_90520
Nimbostratus
Great seems like the different btw IP::local_addr and IP::remote_addr? - Petruk_Cemeng_7
Nimbostratus
We cannot use IP Reputation because [IP::local_addr] is not detected by IP Intelegence database, i tested by cli iprep_lookup.
- BT_90520
Nimbostratus
ok thanks. You tried that with remote_addr also right? - hoolio
Cirrostratus
[IP::local_addr] called in a clientside event like CLIENT_ACCEPTED will return the client's destination IP address (the VS IP for a host VS). As BT says, you'd want to use [IP::client_addr] or [IP::local_addr] which both return the client IP in CLIENT_ACCEPTED. - Petruk_Cemeng_7
Nimbostratus
We previously try to block the ultrasurf , by destination ip address
[IP::local_addr] using ip intelegence . The VS use wildcard 0.0.0.0:443.We log the[IP::local_addr] on eventwhen CLIENT_ACCEPTED ,but when we check the log and check the ip addrss with ipreplookup and also from brightcloud, it's is not detected as malicious ip.That's why i cannot use the ip intelegence to block ultrasurf.-Petruk
- BT_90520
Nimbostratus
[IP::remote_addr] will fit your case as this is the actual address to be submitted for IP intel checks as well in the quarantine IP blacklist maintained in session. local_addr either give you the VS ip or the SNAT src (if enabled) in client and server respectively. I know previously the IP intel did block the Ultrasurf hence why I am asking why not for your case ... unless Ultrasurf has changed in v10 or later. Will you be able to share that Ultrasurf Dest IP you used for checking? - Petruk_Cemeng_7
Nimbostratus
this is sample of the ultrasurf ip address : 65.49.2.15 , 65.49.14.78, 65.49.14.11, i checked on brightcloud but the threadstatus is green
- BT_90520
Nimbostratus
Thanks for sharing. Seems like Brightcloud is not having any flagging on those IP.
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