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Z User edited this page Oct 23, 2026 · 1 revision

Language: English ｜ Networking

Networking

A self-contained TCP/IP stack with everything from NIC drivers to an SSH server - no ported libc, no third-party code.

Bring-up

oc> dhcp                  (request an address on nic0)
oc> ping 10.0.2.2         (ICMP echo to the QEMU gateway)
oc> dns example.com       (resolve via the QEMU DNS forwarder)
oc> wget 10.0.2.2         (fetch http://10.0.2.2/)
oc> wget host 8080 /path  (explicit port and path)
oc> route                 (routing table)
oc> tcpstats              (TCP counters + congestion state)
oc> firewall              (stateful firewall rules)

In QEMU the default -device e1000 matches the e1000 driver out of the box:

qemu-system-x86_64 -m 512 -cdrom opencube.iso \
    -netdev user,id=n1 -device e1000,netdev=n1

Supported NICs

Family Cards Driver
Intel e1000 e1000 (8254x) drivers/nic/driver_nic.c
Intel e1000e 8257x ICH/PCH NICs driver_nic_e1000e.c
Intel igb 82575/82576 (VFs included) driver_nic_igb.c
Intel ixgbe 82598/82599 10 GbE driver_nic_ixgbe.c
Realtek rtl8139 8139/810x fast ethernet driver_nic_rtl8139.c
Realtek rtl8169 8168/8125/810x gigabit families driver_nic_rtl8169.c
Broadcom BCM57xx 5708/5709/5714 era driver_nic_bcm57xx.c

The stack

ARP, IPv4, ICMP, UDP, DNS, TCP with congestion control (net_tcp_cc.c), a socket API for user programs, and a stateful firewall. Every layer is visible through commands: arp, route, tcpstats, firewall, nicstat.

HTTPS client (TLS 1.2 / 1.3)

wget https://... negotiates TLS with RSA and ECDHE key exchange, verifies X.509 chains (RFC 6125 hostname policy - IP-literal URLs have no reference identity), and rejects tampered certificates. The crypto core (AES, SHA-2 family, HMAC, RSA, NIST curves, Ed25519-style primitives) is the same code cryptotest validates with NIST vectors.

DH key exchange correctness and timing: dhtest.

SSH: client and server

  • Client (ssh command): connect, authenticate, run a remote command - key exchange via curve25519-style primitives.

  • Server (sshd): a real SSH server inside the guest. Host and client keys live on the /etc volume (host_keygen_etc seeds them); authorized keys are managed there too. From your host:

    ssh -p <port> root@localhost     (forward a QEMU port to try it)

    The E2E suite exercises a full paramiko login round-trip against the in-guest sshd.

DNS

dns <name> resolves through the configured resolver (QEMU's user-mode stack forwards to the host). Cached entries are visible through the network stats commands.

What is not there (honest list)

  • IPv6 is not implemented.
  • Wi-Fi association: the wireless stack (wifi command) covers status/scan/test across the ath/brcm/iwlwifi/rtlwifi families and the SDIO bus - full association on real hardware depends on the card family; in QEMU there is no Wi-Fi device model to attach.
  • NAT traversal/port forwarding are QEMU user-mode properties, not kernel features.

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