The squid clients are in the 10.48.1.0/24 subnet, the router is in both the 10.48.1.0/24 and the 10.48.33.0/24 subnet. The squid box is 10.48.33.2, the router is 10.48.33.1. Both IP subnets are seperate layer 2 vlans. In the errors below, 10.48.1.200 is my client test machine. Error with "echo 0 > /proc/sys/net/ipv4/ip_nonlocal_bind": 2008/07/22 12:57:05| IPInterception.cc(137) NetfilterInterception: NF getsockopt(SO_ORIGINAL_DST) failed: (11) Resource temporarily unavailable 2008/07/22 12:57:05| IPInterception.cc(171) NetfilterTransparent: NF getsockopt(IP_TRANSPARENT) failed: (92) Protocol not available Error with "echo 1 > /proc/sys/net/ipv4/ip_nonlocal_bind": 2008/07/22 13:01:50| IPInterception.cc(137) NetfilterInterception: NF getsockopt(SO_ORIGINAL_DST) failed: (11) Resource temporarily unavailable 2008/07/22 13:01:50| IPInterception.cc(171) NetfilterTransparent: NF getsockopt(IP_TRANSPARENT) failed: (92) Protocol not available 2008/07/22 13:01:54| commBind: Cannot bind socket FD 30 to 10.48.1.200:5675: (98) Address already in use 2008/07/22 13:01:54| comm.cc(997) commResetFD: bind: (98) Address already in use