URI prefix does not match

Ahah!  So, what happens if you add the whole beginning?

https://rdgateway.domain.com:443/rpc

Cheers - Bob

I am having the same issue I can log in from a MS rdp file on all MS clients but the MS app installed on iOS or android does not work.

If I remove the url hardeidning then the app can login but the client can not.

I used this to set it up:
https://www.winsec.nl/2014/01/15/publishing-rd-gateway-sophos-utms-web-application-firewall/

Were you able to resolve this?
If so could you detail how please.
I have the same issue, where I can connect from a Windows PC, but I get a 403 error from apple devices (including iMac) and from Android devices I get a generic failure to connect message.  On both devices I'm using the RD Client app.

I could not solve it

Want to bump this for exposure, I experience this as well. My other publishing rules work well, but RD Gateway failure is causing me to fall back to NAT rules [:(]

Here is an excerpt of the failure attempt from the live log:
2014:06:24-11:28:08 proxy reverseproxy: srcip="94.186.198.191" localip="192.168.x.y" size="265" user="-" host="94.186.198.191" method="RDG_OUT_DATA" statuscode="401" reason="-" extra="-" exceptions="SkipBlacklistDNSRBL, SkipBlacklistGeoIP, SkipAntiVirus, SkipURLHardening, SkipFormHardening, SkipCookieSigning, SkipThreatsFilter_ProtocolViolations, SkipThreatsFilter_ProtocolAnomalies, SkipThreatsFilter_RequestLimits, SkipThreatsFilter_HttpPolicy, SkipThreatsFilter_BadRobots, SkipThreatsFilter_GenericAttacks, SkipThreatsFilter_SqlInjectionAttacks, SkipThreatsFilter_XssAttacks, SkipThreatsFilter_Trojans, SkipThreatsFilter_Outbound" time="30077" url="/remoteDesktopGateway/" server="remote.domain.com" referer="-" cookie="-" set-cookie="-" 

2014:06:24-11:28:08 proxy reverseproxy: srcip="94.186.198.191" localip="192.168.x.y" size="265" user="-" host="94.186.198.191" method="RDG_IN_DATA" statuscode="401" reason="-" extra="-" exceptions="SkipBlacklistDNSRBL, SkipBlacklistGeoIP, SkipAntiVirus, SkipURLHardening, SkipFormHardening, SkipCookieSigning, SkipThreatsFilter_ProtocolViolations, SkipThreatsFilter_ProtocolAnomalies, SkipThreatsFilter_RequestLimits, SkipThreatsFilter_HttpPolicy, SkipThreatsFilter_BadRobots, SkipThreatsFilter_GenericAttacks, SkipThreatsFilter_SqlInjectionAttacks, SkipThreatsFilter_XssAttacks, SkipThreatsFilter_Trojans, SkipThreatsFilter_Outbound" time="29674" url="/remoteDesktopGateway/" server="remote.domain.com" referer="-" cookie="-" set-cookie="-" 

2014:06:24-11:28:08 proxy reverseproxy: srcip="94.186.198.191" localip="192.168.x.y" size="0" user="-" host="94.186.198.191" method="RDG_IN_DATA" statuscode="200" reason="-" extra="-" exceptions="SkipBlacklistDNSRBL, SkipBlacklistGeoIP, SkipAntiVirus, SkipURLHardening, SkipFormHardening, SkipCookieSigning, SkipThreatsFilter_ProtocolViolations, SkipThreatsFilter_ProtocolAnomalies, SkipThreatsFilter_RequestLimits, SkipThreatsFilter_HttpPolicy, SkipThreatsFilter_BadRobots, SkipThreatsFilter_GenericAttacks, SkipThreatsFilter_SqlInjectionAttacks, SkipThreatsFilter_XssAttacks, SkipThreatsFilter_Trojans, SkipThreatsFilter_Outbound" time="4509" url="/remoteDesktopGateway/" server="remote.domain.com" referer="-" cookie="-" set-cookie="-" 

2014:06:24-11:29:37 proxy reverseproxy: [Tue Jun 24 11:29:37.828229 2014] [proxy_http:error] [pid 13427:tid 4046588784] (-102)Unknown error 4294967194: [client 94.186.198.191:59143] AH01095: prefetch request body failed to 192.168.a.b:443 (192.168.a.b) from 94.186.198.191 () 

2014:06:24-11:29:37 proxy reverseproxy: srcip="94.186.198.191" localip="192.168.x.y" size="357" user="-" host="94.186.198.191" method="RDG_IN_DATA" statuscode="400" reason="-" extra="-" exceptions="SkipBlacklistDNSRBL, SkipBlacklistGeoIP, SkipAntiVirus, SkipURLHardening, SkipFormHardening, SkipCookieSigning, SkipThreatsFilter_ProtocolViolations, SkipThreatsFilter_ProtocolAnomalies, SkipThreatsFilter_RequestLimits, SkipThreatsFilter_HttpPolicy, SkipThreatsFilter_BadRobots, SkipThreatsFilter_GenericAttacks, SkipThreatsFilter_SqlInjectionAttacks, SkipThreatsFilter_XssAttacks, SkipThreatsFilter_Trojans, SkipThreatsFilter_Outbound" time="89625115" url="/remoteDesktopGateway/" server="remote.domain.com" referer="-" cookie="-" set-cookie="-" 

2014:06:24-11:29:37 proxy reverseproxy: [Tue Jun 24 11:29:37.829774 2014] [proxy_http:error] [pid 13427:tid 4054981488] (104)Connection reset by peer: [client 94.186.198.191:59142] AH01110: error reading response 

2014:06:24-11:29:37 proxy reverseproxy: srcip="94.186.198.191" localip="192.168.x.y" size="10" user="-" host="94.186.198.191" method="RDG_OUT_DATA" statuscode="200" reason="-" extra="-" exceptions="SkipBlacklistDNSRBL, SkipBlacklistGeoIP, SkipAntiVirus, SkipURLHardening, SkipFormHardening, SkipCookieSigning, SkipThreatsFilter_ProtocolViolations, SkipThreatsFilter_ProtocolAnomalies, SkipThreatsFilter_RequestLimits, SkipThreatsFilter_HttpPolicy, SkipThreatsFilter_BadRobots, SkipThreatsFilter_GenericAttacks, SkipThreatsFilter_SqlInjectionAttacks, SkipThreatsFilter_XssAttacks, SkipThreatsFilter_Trojans, SkipThreatsFilter_Outbound" time="89751922" url="/remoteDesktopGateway/" server="remote.domain.com" referer="-" cookie="-" set-cookie="-"

I've sanitized a few IP's/hostnames, but this includes the full conversation until failure on the client side.

Version:
Sophos: 9.202-3
Windows Server: 2012 R2 Fully Patched
Windows Client: Windows 8.1
RDP Client Version: 6.3.9600

Happy to troubleshoot/debug anything that helps to facilitate this scenario.

Thanks,
Tim

Seeing similar issues when using SSTP. Here are my live logs for that:
2014:06:25-08:53:47 proxy reverseproxy: [Wed Jun 25 08:53:47.736812 2014] [proxy_http:error] [pid 25331:tid 4130515824] (-102)Unknown error 4294967194: [client 217.7.11.243:49477] AH01095: prefetch request body failed to 192.168.a.b:443 (192.168.a.b) from 217.7.11.243 () 

2014:06:25-08:53:47 proxy reverseproxy: srcip="217.7.11.243" localip="192.168.x.y" size="610" user="-" host="217.7.11.243" method="SSTP_DUPLEX_POST" statuscode="400" reason="-" extra="-" exceptions="SkipBlacklistDNSRBL, SkipBlacklistGeoIP, SkipAntiVirus, SkipURLHardening, SkipFormHardening, SkipCookieSigning, SkipThreatsFilter_ProtocolViolations, SkipThreatsFilter_ProtocolAnomalies, SkipThreatsFilter_RequestLimits, SkipThreatsFilter_HttpPolicy, SkipThreatsFilter_BadRobots, SkipThreatsFilter_GenericAttacks, SkipThreatsFilter_SqlInjectionAttacks, SkipThreatsFilter_XssAttacks, SkipThreatsFilter_Trojans, SkipThreatsFilter_Outbound" time="5823" url="/sra_{BA195980-CD49-458b-9E23-C84EE0ADCD75}/" server="remote.domain.com" referer="-" cookie="-" set-cookie="-" 

Can the change be to offer a GUI to specify allowed methods for any given rule?

Thanks,
Tim

Ahah!  So, what happens if you add the whole beginning?

https://rdgateway.domain.com:443/rpc

Cheers - Bob

Bob, I think I closed the issue at that :443 ar the end of the URL. WAF is not expecting that for a HTTPS connection, so it complains about the URI prefix. I managed to get it working by doing some highly unsupported edditing in my lab's reverseproxy.conf file. I found out that adding a exception using the whole URL to reverseproxy.conf makes it work:

WAFExceptions PATH https://rdgateway.domain.com:443/rpc* SkipURLHardening

Unfortunately, Webadmin won't allow us to add such an exception to URL Hardening. It complains that the path must start with a slash. To circunvent that, I added this exception mannualy to reverseproxy.conf through the shell. It's not a fix nor a workaround, since any modifications o the file gets overwritten in time. Also, it's higly unsupported and may void your warranty. I only did it 'cause it was a lab setup, but at least it helped me zeroing in on the cause. 

Maybe someone from Sophos could take a look at that?

Regards - Giovani

I have the same error when I use the MS client from Android

I get this message:

URI prefix does not match, URI: https://tsmg.xyz.com:443/rpc/rpcproxy.dll?localhost:3388 

with these Entry URLs:
/rpc
/RpcwithCert
https://tsmg.xyz.com:443/rpc