`myIpAddress()`

Returns an IP address of the machine running the PAC. Which address you get is engine-specific.

myIpAddress()  →  string

On machines with several interfaces, VPN clients or IPv6, the address returned is often not the one you expect, so location-based routing with myIpAddress() is fragile. Prefer separate PAC URLs per location or a proxy-side decision.

Example

if (isInNet(myIpAddress(), "10.20.0.0", "255.255.0.0")) {
  return "PROXY proxy-site2.corp.example:8080";
}

Engine notes

Engine	Behaviour	Source
chromium	Returns 127.0.0.1 when no suitable address is found.	code, verified 2026-10-04 services/proxy_resolver/proxy_resolver_v8.cc
firefox	Local address of a socket connected towards the destination host (or 8.8.8.8).	code, verified 2026-10-04 netwerk/base/ProxyAutoConfig.cpp@3f73c528 MyIPAddress()
pacparser	Value set with setmyip(), else the resolution of gethostname().	code, verified 2026-10-04 src/pacparser.c@v1.5.3 my_ip()

Availability

Derived from each engine's vendored helper library plus its native bindings (see engines).
Function	chromium <=51	chromium >=52	firefox all	pacparser <=1.4.6	pacparser 1.5.0	pacparser >=1.5.1	reference all
`myIpAddress`	yes	yes	yes	yes	yes	yes	yes

Related rules

Routing decided by myIpAddress() PAC-K013