Squid proxy stop. I included the log, perhaps someone has seen these lines?
2016/06/01 17:25:08| Starting new negotiateauthenticator helpers...
2016/06/01 17:25:08| helperOpenServers: Starting 1/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:08| Starting new negotiateauthenticator helpers...
2016/06/01 17:25:08| helperOpenServers: Starting 1/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:08| WARNING: All 10/10 negotiateauthenticator processes are busy.
2016/06/01 17:25:08| WARNING: 10 pending requests queued
2016/06/01 17:25:08| WARNING: Consider increasing the number of negotiateauthenticator processes in your config file.
2016/06/01 17:25:08| negotiate_kerberos_auth: INFO: User srossi@VCT.LAN authenticated
2016/06/01 17:25:08| Closing HTTP port 0.0.0.0:3128
2016/06/01 17:25:08| storeDirWriteCleanLogs: Starting...
2016/06/01 17:25:08| Finished. Wrote 0 entries.
2016/06/01 17:25:08| Took 0.00 seconds ( 0.00 entries/sec).
FATAL: Too many queued negotiateauthenticator requests
Squid Cache (Version 3.3.8): Terminated abnormally.
CPU Usage: 0.082 seconds = 0.050 user + 0.032 sys
Maximum Resident Size: 86704 KB
Page faults with physical i/o: 0
Memory usage for squid via mallinfo():
total space in arena: 5984 KB
Ordinary blocks: 5853 KB 2 blks
Small blocks: 0 KB 1 blks
Holding blocks: 36892 KB 8 blks
Free Small blocks: 0 KB
Free Ordinary blocks: 131 KB
Total in use: 42745 KB 714%
Total free: 131 KB 2%
2016/06/01 17:25:08| Starting Squid Cache version 3.3.8 for x86_64-pc-linux-gnu...
2016/06/01 17:25:08| Process ID 30091
2016/06/01 17:25:08| Process Roles: master worker
2016/06/01 17:25:08| With 65536 file descriptors available
2016/06/01 17:25:08| Initializing IP Cache...
2016/06/01 17:25:08| DNS Socket created at [::], FD 5
2016/06/01 17:25:08| DNS Socket created at 0.0.0.0, FD 6
2016/06/01 17:25:08| Adding nameserver 127.0.0.1 from /etc/resolv.conf
2016/06/01 17:25:08| Adding domain vct.lan from /etc/resolv.conf
2016/06/01 17:25:08| helperOpenServers: Starting 0/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:08| helperStatefulOpenServers: No 'negotiate_kerberos_auth' processes needed.
2016/06/01 17:25:08| helperOpenServers: Starting 5/5 'ext_ldap_group_acl' processes
2016/06/01 17:25:08| negotiate_kerberos_auth: INFO: User srossi@VCT.LAN authenticated
2016/06/01 17:25:08| negotiate_kerberos_auth: INFO: User srossi@VCT.LAN authenticated
2016/06/01 17:25:08| negotiate_kerberos_auth: INFO: User srossi@VCT.LAN authenticated
2016/06/01 17:25:08| negotiate_kerberos_auth: INFO: User srossi@VCT.LAN authenticated
2016/06/01 17:25:08| Logfile: opening log /var/log/squid3/access.log
2016/06/01 17:25:08| WARNING: log parameters now start with a module name. Use 'stdio:/var/log/squid3/access.log'
2016/06/01 17:25:08| Local cache digest enabled; rebuild/rewrite every 3600/3600 sec
2016/06/01 17:25:08| Logfile: opening log /var/log/squid3/store.log
2016/06/01 17:25:08| WARNING: log parameters now start with a module name. Use 'stdio:/var/log/squid3/store.log'
2016/06/01 17:25:08| Swap maxSize 0 + 262144 KB, estimated 20164 objects
2016/06/01 17:25:08| Target number of buckets: 1008
2016/06/01 17:25:08| Using 8192 Store buckets
2016/06/01 17:25:08| Max Mem size: 262144 KB
2016/06/01 17:25:08| Max Swap size: 0 KB
2016/06/01 17:25:08| Using Least Load store dir selection
2016/06/01 17:25:08| Set Current Directory to /var/spool/squid3
2016/06/01 17:25:08| Loaded Icons.
2016/06/01 17:25:08| HTCP Disabled.
2016/06/01 17:25:08| commBind: Cannot bind socket FD 20 to [::1]: (99) Cannot assign requested address
2016/06/01 17:25:08| commBind: Cannot bind socket FD 21 to [::1]: (99) Cannot assign requested address
2016/06/01 17:25:08| ERROR: Failed to create helper child read FD: UDP[::1]
2016/06/01 17:25:08| Configuring Parent 127.0.0.1/3130/0
2016/06/01 17:25:08| Squid plugin modules loaded: 0
2016/06/01 17:25:08| Adaptation support is off.
2016/06/01 17:25:08| Accepting HTTP Socket connections at local=0.0.0.0:3128 remote=[::] FD 19 flags=9
2016/06/01 17:25:08| Starting new negotiateauthenticator helpers...
2016/06/01 17:25:08| helperOpenServers: Starting 1/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:08| Starting new negotiateauthenticator helpers...
2016/06/01 17:25:08| helperOpenServers: Starting 1/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:08| Starting new negotiateauthenticator helpers...
2016/06/01 17:25:08| helperOpenServers: Starting 1/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:08| Starting new negotiateauthenticator helpers...
2016/06/01 17:25:08| helperOpenServers: Starting 1/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:08| Starting new negotiateauthenticator helpers...
2016/06/01 17:25:08| helperOpenServers: Starting 1/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:08| Starting new negotiateauthenticator helpers...
2016/06/01 17:25:08| helperOpenServers: Starting 1/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:08| Starting new negotiateauthenticator helpers...
2016/06/01 17:25:08| helperOpenServers: Starting 1/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:08| Starting new negotiateauthenticator helpers...
2016/06/01 17:25:08| helperOpenServers: Starting 1/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:08| Starting new negotiateauthenticator helpers...
2016/06/01 17:25:08| helperOpenServers: Starting 1/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:08| Starting new negotiateauthenticator helpers...
2016/06/01 17:25:08| helperOpenServers: Starting 1/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:08| WARNING: All 10/10 negotiateauthenticator processes are busy.
2016/06/01 17:25:08| WARNING: 10 pending requests queued
2016/06/01 17:25:08| WARNING: Consider increasing the number of negotiateauthenticator processes in your config file.
2016/06/01 17:25:08| Closing HTTP port 0.0.0.0:3128
2016/06/01 17:25:08| storeDirWriteCleanLogs: Starting...
2016/06/01 17:25:08| Finished. Wrote 0 entries.
2016/06/01 17:25:08| Took 0.00 seconds ( 0.00 entries/sec).
FATAL: Too many queued negotiateauthenticator requests
Squid Cache (Version 3.3.8): Terminated abnormally.
CPU Usage: 0.075 seconds = 0.036 user + 0.039 sys
Maximum Resident Size: 87440 KB
Page faults with physical i/o: 0
Memory usage for squid via mallinfo():
total space in arena: 6260 KB
Ordinary blocks: 6199 KB 44 blks
Small blocks: 0 KB 1 blks
Holding blocks: 36892 KB 8 blks
Free Small blocks: 0 KB
Free Ordinary blocks: 60 KB
Total in use: 43091 KB 688%
Total free: 60 KB 1%
2016/06/01 17:25:09| Starting Squid Cache version 3.3.8 for x86_64-pc-linux-gnu...
2016/06/01 17:25:09| Process ID 30117
2016/06/01 17:25:09| Process Roles: master worker
2016/06/01 17:25:09| With 65536 file descriptors available
2016/06/01 17:25:09| Initializing IP Cache...
2016/06/01 17:25:09| DNS Socket created at [::], FD 5
2016/06/01 17:25:09| DNS Socket created at 0.0.0.0, FD 6
2016/06/01 17:25:09| Adding nameserver 127.0.0.1 from /etc/resolv.conf
2016/06/01 17:25:09| Adding domain vct.lan from /etc/resolv.conf
2016/06/01 17:25:09| helperOpenServers: Starting 0/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:09| helperStatefulOpenServers: No 'negotiate_kerberos_auth' processes needed.
2016/06/01 17:25:09| helperOpenServers: Starting 5/5 'ext_ldap_group_acl' processes
2016/06/01 17:25:09| Logfile: opening log /var/log/squid3/access.log
2016/06/01 17:25:09| WARNING: log parameters now start with a module name. Use 'stdio:/var/log/squid3/access.log'
2016/06/01 17:25:09| Local cache digest enabled; rebuild/rewrite every 3600/3600 sec
2016/06/01 17:25:09| Logfile: opening log /var/log/squid3/store.log
2016/06/01 17:25:09| WARNING: log parameters now start with a module name. Use 'stdio:/var/log/squid3/store.log'
2016/06/01 17:25:09| Swap maxSize 0 + 262144 KB, estimated 20164 objects
2016/06/01 17:25:09| Target number of buckets: 1008
2016/06/01 17:25:09| Using 8192 Store buckets
2016/06/01 17:25:09| Max Mem size: 262144 KB
2016/06/01 17:25:09| Max Swap size: 0 KB
2016/06/01 17:25:09| Using Least Load store dir selection
2016/06/01 17:25:09| Set Current Directory to /var/spool/squid3
2016/06/01 17:25:09| Loaded Icons.
2016/06/01 17:25:09| HTCP Disabled.
2016/06/01 17:25:09| commBind: Cannot bind socket FD 20 to [::1]: (99) Cannot assign requested address
2016/06/01 17:25:09| commBind: Cannot bind socket FD 21 to [::1]: (99) Cannot assign requested address
2016/06/01 17:25:09| ERROR: Failed to create helper child read FD: UDP[::1]
2016/06/01 17:25:09| Configuring Parent 127.0.0.1/3130/0
2016/06/01 17:25:09| Squid plugin modules loaded: 0
2016/06/01 17:25:09| Adaptation support is off.
2016/06/01 17:25:09| Accepting HTTP Socket connections at local=0.0.0.0:3128 remote=[::] FD 19 flags=9
2016/06/01 17:25:09| Starting new negotiateauthenticator helpers...
2016/06/01 17:25:09| helperOpenServers: Starting 1/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:09| Starting new negotiateauthenticator helpers...
2016/06/01 17:25:09| helperOpenServers: Starting 1/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:09| Starting new negotiateauthenticator helpers...
2016/06/01 17:25:09| helperOpenServers: Starting 1/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:09| negotiate_kerberos_auth: INFO: User asaleh@VCT.LAN authenticated
2016/06/01 17:25:09| negotiate_kerberos_auth: INFO: User asaleh@VCT.LAN authenticated
2016/06/01 17:25:09| negotiate_kerberos_auth: INFO: User asaleh@VCT.LAN authenticated
2016/06/01 17:25:09| negotiate_kerberos_auth: INFO: User mgayoso@VCT.LAN authenticated
2016/06/01 17:25:09| Starting new negotiateauthenticator helpers...
2016/06/01 17:25:09| helperOpenServers: Starting 1/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:09| Starting new negotiateauthenticator helpers...
2016/06/01 17:25:09| helperOpenServers: Starting 1/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:09| Starting new negotiateauthenticator helpers...
2016/06/01 17:25:09| helperOpenServers: Starting 1/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:09| Starting new negotiateauthenticator helpers...
2016/06/01 17:25:09| helperOpenServers: Starting 1/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:09| Starting new negotiateauthenticator helpers...
2016/06/01 17:25:09| helperOpenServers: Starting 1/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:09| Starting new negotiateauthenticator helpers...
2016/06/01 17:25:09| helperOpenServers: Starting 1/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:09| Starting new negotiateauthenticator helpers...
2016/06/01 17:25:09| helperOpenServers: Starting 1/10 'negotiate_kerberos_auth' processes
2016/06/01 17:25:09| WARNING: All 10/10 negotiateauthenticator processes are busy.
2016/06/01 17:25:09| WARNING: 10 pending requests queued
2016/06/01 17:25:09| WARNING: Consider increasing the number of negotiateauthenticator processes in your config file.
I see by "saint google" increasing the kerberos helpers to 25 and the ntml helpers to 40 but I don't know rewrite template on zentyal server.
cheers.