[squid-users] handshake problems with stare and bump

Mon Oct 3 18:09:28 UTC 2016

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http://wiki.squid-cache.org/ConfigExamples/Intercept/SslBumpExplicit#Hardening


03.10.2016 23:50, Marc пишет:
> Hi,
>
> I've got an issue with squid stare and bump, hope someone can help!
>
> I'm staring and bumping everything, using transparent proxy on Fedora
> Core 24 using squid-3.5.20-1.fc24.x86_64 (see below for config). Now
> the client (iphone app) does TLS v1.0 and has the following ciphers in
> the Client Hello (from wireshark):
> TLS_RSA_WITH_AES_256_CBC_SHA (0x0035)
> TLS_RSA_WITH_AES_128_CBC_SHA (0x002f)
> TLS_RSA_WITH_3DES_EDE_CBC_SHA (0x000a)
> TLS_RSA_WITH_RC4_128_SHA (0x0005)
> TLS_RSA_WITH_RC4_128_MD5 (0x0004)
> TLS_RSA_WITH_DES_CBC_SHA (0x0009)
>
> What squid does is replicating all of them in the Client Hello to the
> server. This in general goes without problems most of the time, but in
> this case not. In the cases where it fails, squid logs an error:
> 2016/10/01 00:08:13 kid1| Error negotiating SSL on FD 26:
> error:1409F07F:SSL routines:ssl3_write_pending:bad write retry
> (1/-1/0)
> I've also seen:
> 2016/10/02 20:53:09 kid1| Error negotiating SSL connection on FD 12:
> error:1408A0C1:SSL routines:ssl3_get_client_hello:no shared cipher
> (1/-1)
>
> Squid then sends the following html to the client (http over https
> port 443 - I had to get it out of my pcap):
>
> --
> (71) Protocol error (TLS code: SQUID_ERR_SSL_HANDSHAKE)
> Handshake with SSL server failed: error:1409F07F:SSL
> routines:ssl3_write_pending:bad write retry
> This proxy and the remote host failed to negotiate a mutually
> acceptable security settings for handling your request. (..)
> --
> Now it would've been nicer if squid sent out that error over HTTPS,
> but my main problem is the error happening in the first place.
>
> I think it has something to do with the cipher. If I look at my pcaps
> I can see the webserver is selecting 'TLS_RSA_WITH_3DES_EDE_CBC_SHA
> (0x000a)' in the Server Hello. In openssl, this cipher is called
> 'DES-CBC3-SHA'. So if I try to reproduce on another client (linux),
> only using one cipher in the client hello:
> 1) echo -e "GET / HTTP/1.1\nHost: $host\n\n" | openssl s_client
> -cipher DES-CBC3-SHA -quiet -connect $host:443 2>/dev/null
> 2) echo -e "GET / HTTP/1.1\nHost: $host\n\n" | openssl s_client
> -cipher AES256-SHA -quiet -connect $host:443 2>/dev/null
>
> 1 breaks like the iphone app. 2 works fine. I've looked on the host
> squid is running on, but 1 works there as well. So the host running
> squid seems to support the cipher, also according to openssl:
> # openssl ciphers -V | grep "0x00,0x0A"
>           0x00,0x0A - DES-CBC3-SHA            SSLv3 Kx=RSA      Au=RSA
>  Enc=3DES(168) Mac=SHA1
>
> Things that come to mind:
> 1) Why doesn't DES-CBC3-SHA work with squid ? The host seems to
supports it.
> 2) Squid forwards the Client Hello, including ciphers the host running
> squid doesn't support (in my case, the DES and RC4 ones). This could
> also potentially lead to problems. Why doesn't squid filter them out
> from the Client Hello sent from squid to the webserver ? Or replace
> all of them with the ciphers preferred by squid. Perhaps by using the
> sslproxy_cipher directive (which is currently ignored in ssl_bump
> configurations).
> 3) Nice to have: Is it possible for squid to report errors to the user
> over HTTPS instead of HTTP ?
>
> My squid conf:
>
> #####################################
> http_port      3128 transparent
> https_port     3129 transparent ssl-bump generate-host-certificates=on
> dynamic_cert_mem_cache_size=100MB
> cert=/etc/pki/rootca/public+private.pem
> http_port      3130 ssl-bump generate-host-certificates=on
> dynamic_cert_mem_cache_size=100MB
> cert=/etc/pki/rootca/public+private.pem
>
> logformat      combined %>a %ui %un [%tl] "%rm %ru HTTP/%rv" %Hs %<st
> "%{Referer}>h" "%{User-Agent}>h" %Ss:%Sh
> access_log     /export/logs/squid/access_log combined
> cache_log      /export/logs/squid/cache_log
> coredump_dir   /var/spool/squid
>
> acl localhost  src    127.0.0.1/32 ::1
>
> acl localnet   src    10.5.0.0/16
> acl localnet   src    fc00::/7
> acl localnet   src    fe80::/10
>
> acl SSL_ports  port   443
> acl Safe_ports port   80
> acl Safe_ports port   443
> acl CONNECT    method CONNECT
>
> http_access    allow  manager     localhost
> http_access    deny   manager
> http_access    deny   !Safe_ports
> http_access    deny   CONNECT     !SSL_ports
> http_access    allow  localnet
> http_access    allow  localhost
> http_access    deny   all
>
> forwarded_for  delete
> cache deny     all
> always_direct  allow  all
>
> ssl_bump       stare  all
> ssl_bump       bump   all
> #####################################
>
> Thanks,
>
> Marc
> _______________________________________________
> squid-users mailing list
> squid-users at lists.squid-cache.org
> http://lists.squid-cache.org/listinfo/squid-users

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