pddm,
1)
Thank you for your response. Actually, I
am assigning a complete block of IPs to eth0 and they are mostly consecutive. They are A.B.C.19, A.B.C.153, A.B.C.154, ..., A.B.C.158. I have them on eth0, eth0:0, eth0:1, ..., eth0:5, respectively.
I'm not sure how assigning only one IP in a block would be effective. We do own all seven IPs and have specific uses in mind for each of them. I have just successfully managed to get all traffic from my desktop to come from A.B.C.153. My roommate's desktop is on A.B.C.154 and other, unspecified traffic is using our original IP (A.B.C.19).
Primarily, we are trying to allow machines on the inside of the network to have distinct IP addresses on the outside network. Additionally, we want the ability to shuffle things around in special cases. For example, we can't get eight computers into a Diablo II Battle.Net game because the server only allows four connections per IP address... so I intend to have the firewall choose a distinct IP address for each connection created by a computer on the LAN, if possible, thus dodging that constraint. The fact that the latter six IP addresses are in a block is purely coincidental.
2)
Why shouldn't I use eth0:0, out of curiosity? It seems to have taken the IP just fine and, when researching how to assign multiple IP addresses to one card, I ran into a post which suggested using it. Is there some danger of conflict with eth0?
The output of my ifconfig looks something like this:
Code:
eth0 Link encap:Ethernet HWaddr UU:VV:WW:XX:YY:ZZ
inet addr:A.B.C.19 Bcast:A.B.C.127 Mask:255.255.255.128
{snip}
Interrupt:11 Base address:0xd800
eth0:0 Link encap:Ethernet HWaddr UU:VV:WW:XX:YY:ZZ
inet addr:A.B.C.153 Bcast:A.B.C.159 Mask:255.255.255.248
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:11 Base address:0xd800
eth0:1 Link encap:Ethernet HWaddr UU:VV:WW:XX:YY:ZZ
inet addr:A.B.C.154 Bcast:A.B.C.159 Mask:255.255.255.248
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:11 Base address:0xd800
eth0:2 Link encap:Ethernet HWaddr UU:VV:WW:XX:YY:ZZ
inet addr:A.B.C.155 Bcast:A.B.C.159 Mask:255.255.255.248
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:11 Base address:0xd800
eth0:3 Link encap:Ethernet HWaddr UU:VV:WW:XX:YY:ZZ
inet addr:A.B.C.156 Bcast:A.B.C.159 Mask:255.255.255.248
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:11 Base address:0xd800
eth0:4 Link encap:Ethernet HWaddr UU:VV:WW:XX:YY:ZZ
inet addr:A.B.C.157 Bcast:A.B.C.159 Mask:255.255.255.248
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:11 Base address:0xd800
eth0:5 Link encap:Ethernet HWaddr UU:VV:WW:XX:YY:ZZ
inet addr:A.B.C.158 Bcast:A.B.C.159 Mask:255.255.255.248
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:11 Base address:0xd800
eth1 Link encap:Ethernet HWaddr UU:VV:WW:XX:YY:ZZ
inet addr:192.168.0.131 Bcast:192.168.0.255 Mask:255.255.255.0
{snip}
Interrupt:10 Base address:0xe800
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:77 errors:0 dropped:0 overruns:0 frame:0
TX packets:77 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:12470 (12.1 Kb) TX bytes:12470 (12.1 Kb)
Does that look alright?
3)
So eth0:1 isn't treated as a separate interface from eth0:2, then? That's good. It makes working with tc qdisc a lot easier.
4)
I rewrote my firewall script to assume that assigning rules to eth0 was sufficient and it seems to be working. Nonetheless, it's good to hear confirmation of this behavior, as it makes me a lot more confident in the script (which I just threw together today based upon my own limited knowledge).
Thanks for all your help! You've been quite informative and I really appreciate it; after all, I couldn't find any information on this phenomenon (eth0:n) and I didn't even know what it was called or why it was happening.
Much gratitude!