On Mon, 14 Nov 2011 14:50:02 +0000, John Sayce wrote:
I have squid configured and working fine with ntlm authentication,
however about once a week access to the throughput will slow and I
can
be presented with access denied messages. Restarting squid instantly
fixes the problem. My configuration is relatively simple as bellow.
I
don't have a large user base. There's only 60 users and the problem
is
instantly gone upon restarting squid which suggests to me that it's
not simply be a problem of load as the log would suggest. I wondered
if it was a single computer or application causing the issue but I'm
not sure how to find out.
http_port 8080
auth_param ntlm program c:/squid/libexec/mswin_ntlm_auth.exe
auth_param ntlm children 30
external_acl_type win_domain_group children=30 ttl=120 %LOGIN
c:/squid/libexec/mswin_check_lm_group.exe -G
acl all src 0.0.0.0/0.0.0.0
acl nocache dstdomain "C:\squid\etc\nocache_domains.acl"
acl unauthenticatednet src "C:\squid\etc\unrestrictedaddresses.acl"
acl blocked src "C:\squid\etc\restrictedaddresses.acl"
acl inetallowgroup external win_domain_group InternetAllow
acl inetrestrictgroup external win_domain_group InternetRestricted
acl localhost src 127.0.0.1/255.255.255.255
acl localnet proxy_auth REQUIRED src 192.168.0.0/255.255.255.0
The above ACL definition has never been valid.
Perhapse you wanted:
acl localnet src 192.168.0.0/24
acl login proxy_auth REQUIRED
http_access deny !localnet
http_access deny !login
The "deny !localnet" will prevent non-LAN users from logging in. If you
can do that great. It will prevent external machines flooding your proxy
with malicious login load.
The "deny !login" is to do the user login quickly and reject early if
they fail that. From your logs below I see 3x lookups being done, one
for each group check. All of which are failing due to invalid domain
name on the user credentials. Doing this "deny !login" will drop the
speed loss on the failure cases by more than 60%.
acl denied_domains dstdomain "C:\squid\etc\denied_domains.acl"
acl allowed_domains dstdomain "C:\squid\etc\allowed_domains.acl"
acl allowed_addresses dst "C:\squid\etc\allowed_addresses.acl"
acl manager proto cache_object
always_direct allow nocache
http_access allow manager monitor
http_access deny localhost
http_access deny blocked
http_access allow unauthenticatednet
http_access allow allowed_domains
http_access allow allowed_addresses
NP: "allowed_addresses" requires DNS lookup. So slows every request
down to find the requested domains DNS entries.
http_access deny inetrestrictgroup denied_domains
Swap those ACLs order to:
denied_domains inetrestrictgroup
That will reduce the helper lookup load on the !denied_domains cases a
bit.
http_access allow inetrestrictgroup
http_access allow inetallowgroup
http_access deny all
cache_mem 500 MB
maximum_object_size_in_memory 1 MB
cache_dir ufs c:/squid/var/cache 7000 16 512
access_log C:\squid\var\logs\access.log squid.
My cache log would seem to suggest that it's related to the ntlm
helper processes. Eg
/mswin_check_lm_group.exe Can't find DC for local domain 'asd'
Your DC has disappeared, or some client is sending in a login domain
which is not yours.
Nothing the helpers can do about either case but reject. It does so,
after the horribly long lag it took to discover that problem.
I think this is the output of checking "deny inetrestrictgroup
denied_domains".
2011/11/14 11:31:57| storeUfsCreate: Failed to create
c:/squid/var/cache/01/C2/00058467 ((13) Permission denied)
/mswin_check_lm_group.exe Can't find DC for local domain 'asd'
Login checks repeat all over again. And fail again.
I think this is the output of checking "allow inetrestrictgroup".
/mswin_check_lm_group.exe Can't find DC for local domain 'asd'
Login checks repeat all over again. And fail yet again.
I think this is the output of checking "allow inetrestrictgroup".
2011/11/14 12:15:40| clientTryParseRequest: FD 361
(192.168.0.252:2504) Invalid Request
2011/11/14 12:26:41| sslWriteClient: FD 1062: write failure: (10054)
WSAECONNRESET, Connection reset by peer..
And the client disconnects.
"sslWriteClient" seems significant. Particularly since your config has
no https_port.
What Squid version are you using?
And the cache authentication statistics seem to sugget the same
<snip a list of client credentials. careful.>
Well the helpers report indicates it is taking up to 25 seconds to do
*1* login request for some clients.
What this looks like to me is either your DC disappearing for a short
while and Squid falling under the resulting failures.
Or some client flooding Squid with the invalid domain name 'asd' with
the same effect.
Amos
