[squid-users] Header forgery detected

[Darren Breeze]

Hi All

I am trying to set up squid 3.5 (have to stick with this version) to intercept and https bump / splice, it's all working OK with the exception of some elements of a https site failing to load (the browser just shows "failed"). matched with the failures, I see this type of message in the cache log. 

2019/11/08 17:39:46 kid1| SECURITY ALERT: Host header forgery detected on local=23.213.186.14:443 remote=172.16.3.250:57041 FD 28 flags=33 (local IP does not match any domain IP)
2019/11/08 17:39:46 kid1| SECURITY ALERT: on URL: static1.squarespace.com:443

172.16.3.250 is the clients PC address. 

doing a lookup on the hostname returns

root at cbuild:~/build/ksn-boot/cmake-build-debug/bin# nslookup
> server 127.0.0.1
Default server: 127.0.0.1
Address: 127.0.0.1#53
> static1.squarespace.com
Server: 127.0.0.1
Address: 127.0.0.1#53

Non-authoritative answer:
static1.squarespace.com canonical name = prod.squarespace.map.fastly.net.
Name: prod.squarespace.map.fastly.net
Address: 151.101.0.238
Name: prod.squarespace.map.fastly.net
Address: 151.101.64.238
Name: prod.squarespace.map.fastly.net
Address: 151.101.128.238
Name: prod.squarespace.map.fastly.net
Address: 151.101.192.238

so the address is different and points to a CDN endpoint 

14.186.213.23.in-addr.arpa name = a23-213-186-14.deploy.static.akamaitechnologies.com.


The host is ubuntu 18.04 and both squid and the client are using the DNS on the squid box. 

Can anyone please point me where I need to start looking

thanks in advance

Darren B.


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